Class 8

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 10 Not For Drinking-Not For Breathing Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 10th Lesson Not For Drinking-Not For Breathing

8th Class Biology 10th Lesson Not For Drinking-Not For Breathing Textbook Questions and Answers

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Question 1.
How does air pollution lead to water pollution?
Answer:

1. Air and water are not separate problem. There is a close link between the health of air and the health of water.
2. Nitrogen and chemical contaminants are two types of pollutants that harm both the air and water.
3. Up to l/3rd of the nitrogen that pollutes the bay and it’s rivers comes from the air.
4. Air pollution from a very large geographic area can eventually wind up in the Bay.
5. Use of fertilizers and pesticides in agriculture pollutes not only air but also land and water.
6. Sources of air pollution includes vehicles, industries, power plants and farm operations which lead to water pollution.

Question 2.
What steps can be taken up to control air pollution and water pollution?
Answer:
Some of the methods for controlling air pollutions are:

1. Tall chimneys should be installed in all factories to reduce air pollution at the ground level.
2. Better designed fuel burning equipment should be used in homes and industries so that fuel burnt completely.
3. Install electrostatic precipitators in the chimneys of industries.
4. Reduce vehicular emissions by using non polluting fuels like CNG (compressed natural gas)
5. Use LPG for domestic use (Liquify Petroleum Gas)
6. Improve the quality of fuel in automobiles and use catalytic converters in them.
7. Make use of renewable alternative source of energy like solar energy, wind energy and hydro energy.
8. All motor vehicles should be maintained properly so that they comply with pollution norms.
9. Use unleaded petrol.
10. Plant and grow, more and more trees, we can protect plants and trees. Vanamahotsav should be continued every year in July month.

Prevention and controlling of water pollution

1. Toxic industrial wastes should be treated chemically to neutralize the harmful substances present in it before discharging into rivers and lakes.
2. The sewage should not be dumped in to the rivers directly.
3. The use of excessive fertilizers and pesticides should be avoided.
4. The use of synthetic detergent should be minimized or biodegradable detergents should be used.
5. Dead bodies of human beings and animals should not be thrown into rivers.
6. The excreta and other garbage should be treated in a biogas plant to get fuel as well as manure.
7. The water of rivers, streams, ponds and lakes should be purified or cleaned. For example Ganga action plait launched by the Indian Government.
8. Trees and shrubs should bp planted along the banks of the rivers.
9. There should be general Rareness among the people regarding the harmful of water pollution and the ways of prevention.
10. Waste papers, plastic, waste fbod materials and rotten food and vegetables should not be thrown into open drains.
11. Go for the alternate energy resources that can replenish themselves without affecting our environment.
12. Reuse the materials for secondary purpose. Recycling is the next stage of reuse.

Question 3.
Why does the increased level of nutrients in the water affect the survival of aquatic organisms?
Answer:
Plants nutrients:

1. Phosphates and nitrates – chemical fertilizers from agriculture run – off due to rain and industrial wastes enter into water through sewage and pollute the water.
2. It helps algae to bloom, weeds to grow and bacteria is spread. As a result water turn green and cloudy and smell bad.
3. Decomposing plants use up the oxygen in water, disrupting aquatic life, reducing biodiversity and even killing aquatic life.
4. Thus, this enrichment of water by nutrients leading to excessive plant growth and depletion of oxygen is known as ‘Eutrophication’. This affects aquatic life badly.

Question 4.
Road side plants cannot grow properly. Find your own reasons and explain with your argument.
Answer:

1. The plantation along the roads mainly includes neem, peepal, banyan, almond etc.
2. It was observed that vegetation at roadside with heavy traffic and markets was much affected by vehicular emissions.
3. Significant decrease in total chlorophyll and protein content was observed with reduced leaf area.
4. It is concluded that plants can be uses as indicators for urban air pollution and there is need to protect the road side plants from air pollution.
5. Biomonitoring of plants is an important tool to evaluate the impact of air pollution on plants.
6. A study suggests that plants have the potential to serve as excellent quantitative and qualitative indices of pollution levels.
7. So plants should be grown and protected.

Question 5.
Sudheer is a traffic constable. What do you think about his health? Give some suggestions to protect his health during duty period.
Answer:

1. Environmental pollution place a significance role in the development of various respiratory diseases. Different particles and gases from vehicular emissions like carbondioxide, carbon monoxide, sulphur, benzene, lead, nitrogen dioxide and black smoke are the root of the problem.
2. Traffic police are increasingly becoming victims of a diabetes and allergies at a younger age. Irregular work schedule were posing a challenge to the health of the police. Besides physical strain, mental stress and asymmetrical food habits are also contributing the problem.
3. The traffic police men who work at busy intersections are at the highest risk of developing asthma, bronchitis, shortness of breath, sore throat, chest pain, lung cancer, eye irritation, skin ailments. Impaired hearing, excessive carboxy haemoglobin and annoyance with noise also high blood pressure and cardiovascular problems.
4. On the basis of the study, pollution masks should be used by the traffic police men on duty at higher polluted junctions.
5. He should be recommended better and special medical care for his protection. Various duty places for them need to be scientifically evaluated for their exposure risk.
6. To protect ears from deafening noises, they can put small cotton balls in the ear and also wear ear masks for this purpose.
7. Ecofriendly solar traffic booths at traffic intersections will be provided for the traffic police men. These booths contains ionisers which supress the suspended particulate matter and provide a healthy environment for a police man seated inside.

Question 6.
Write a short note on the effects of water pollution in your village. Suggest precautions.
Answer:

1. Patancheru is a suburban mandal headquarters in Medak district, located about 25 km from Hyderabad. It is a major industrial hub of the state.
2. It is one of the most polluted areas in India. Nearly 14 villages were badly affected by pollution related diseases like cancer, respiratory diseases and heart diseases caused by number of poisons in air, water and on land.
3. The presence of pharmaceutical and chemical industries, pesticide units, steel rolling industries, distilleries releasing the pollutants like chlorine, Hydrogen sulphide, which are entering into the atmosphere.
4. Most of the agricultural lands became barren. The lives of people there depend on agriculture and animal husbandry. They became helpless. Most of the people converted themselves as workers in the factories.

Question 7.
Visit a pollution check centre. Observe the process of conducting a pollution check and record your findings. You may consider the following areas your record.
Average number of vehicles checked in a certain time period, Time taken to check each vehicle, Pollutants checked for, The process of testing, Permissible limits of emission of various pollutants, Measures taken if the emitted gases are above the permissible limits.

• % Average number of vehicles checked in a certain time period.
  Answer:
  10-15
• Time taken to check each vehicle.
  Answer:
  5-7 minutes
• Pollutants checked for
  Answer:
  Carbon dioxide, carbon monoxide, nitrogen, nitrogen oxide, methane, hydro carbons, sulphur dioxide, particular matter, trace elements, water vapour etc.
• The process of testing:
  1. The test shall be carried out with the engine mounted on a test bench and connected to a dynamometer.
  2. The gases emission from the exhaust of the engine include hydrocarbons, carbondioxide, carbon monoxide and oxides of nitrogen.
  3. During prescribed sequence of warmed up engine operating conditions, the amount of the above gases in the exhaust, shall be examined continuously.
  4. The prescribed sequence of operations consists of a number of speed and power modes which span the typical operating range of engine.
  5. During each mode, the concentration of each pollutant, exhaust flow and power out put shall be determined and the measured values, weighed and used to calculate the grams of each pollutant emitted for kilowatt hour.
• Permissible limits of emission of various pollutants.
  Pefrol engine
  Carbondioxide                                  14%
  Carbon monoxide                            1 to 2%
  Nitrogen oxide less than                  0.5%
  Hydrocarbons                                   0.5%
  Sulphur dioxide                                possible traces
  Particular matter less than                0.5%
  Trace elements less than                   0.5%
  Nitrogen                                            71%
  Water vapour                                    12%
  Diesel Engine
  Nitrogen                                                   67%
  Carbondioxide                                          13%
  Water vapour                                            11%
  Carbon monoxide                             less than 0.045%
  Nitrogen oxide                                 less than 0 to 1.5%
  Sulphur dioxide                                less than 0.03%
  Hydro carbons                                  less than 0.43%
  Particulate Pollutants                       less than 0.045%
  Trace elements                                           0.3%
• Measures taken if the emitted gases are above the permissible limits.
  Answer:
  The carbon particles (soot) deposited in the engine head will be checked and cleaned or the vehicle will be ceased by .R.T.O.

Question 8.
Organize a field visit to a pond/lake/river present in or near to your village with the help of your teachers.
Observations followed by discussion could focus on…. The history of the pond or lake or river, Water resources available other than that river/pond/or lake, Cultural traditions, Pollution concerns, Source of pollution, Effects of pollution on the people living by the river side as well as those living far away.
Answer:
Kolleru lake: It is a 2nd largest fresh water lake located in Andhra Pradesh located between Krishna and Godavari delta.
History: Two copper plates of the early Pallava dynasty have been found in the lake, tracing it’s history to Langula Narasimha Deva an Ganga Vanshi Odisha King. According to legend, the Gajapathi fort was located at Kolleti kota on one of the eastern islands of the lake. The enemy general “Muhammadan” general escamped at “Chiguru kota” located on the shores. In some ways the lake protected the Oriya forces. The enemy finally tried to excavate a channel, the modern day Upputeru. So that the water of the lake would empty into the sea and the level would fall so that they could attack the Gajapathi fort. The royal oriya army general sacrificed his own daughter to propitiate Gods and ensure his success against Muhammadan and her name was “Perantala Kanama”. Therefore the channel Was called perantala Kanama. “Sri Peddinti Ammavari Temple” is one of the oldest and famous temples found in Kolleru.
Water sources available other than Kolleru: Wells, taps. The lake is fed directly water from seasonal Budameru and Tammileru streams and connected to the Krishna and Godavari systems by channels.
Cultural traditions: The vast majority of the district is rural in nature. Thus the culture of the kolleru lake people is mostly conservative and traditional. The joint family system, the arranged marriages are the norms. Telugu language is spoken in this place. Pollution concerns: Kolleru lake is suffering from the unsatisfied greed of people and selfish interests of mankind who exploit the lake’s integrity. Thousands of fish tanks were dug up effectively converting the lake into a mere drain. This had great impact in terms of pollution, leading to difficulty in getting drinking water for the local people.
Source of pollution: Satellite images taken on February 9, 2001 by the Indian remote sensing satellite found that approximately 42% of the 245 km² lake was occupied by aquaculture. While agriculture had encroached another 8.5% they were mostly rice paddies. Surprisingly no clear water could be found in the satellite image. The rest of the lake is being diminished by weeds like elephant grass and water hyacinth.
Effects of pollution on people: Thousands of fish tanks were dug up effectly leading to difficulty in getting drinking water for the local people. An adverse effect on the thousands of acres of crop in the upper reaches of water flow into the sea because of obstruction by bunds of the fish tanks that appeared illegally.

Question 9.
What is air pollution? Make a flow-chart to describe its causes and effects.
Answer:
If solid, liquid and gaseous substances are present in higher volumes than required in the air, it is harmful to air. It is called air pollution.
Table shows causes and effects of air pollution:

COMMON POLLUTANTS AND THEIR SOURCES

Question 10.
Clear and transparent water is always suitable for drinking. Comment.
Answer:

1. No. Clear and transparent water is not always suitable for drinking.
2. Water might appears clean but it may contain some disease causing micro-organisms and other dissolved impurities.
3. Hence it is advised to purify water before drinking.
4. Purifying can be done by water purifying systems or by boiling the water.

Question 11.
If our monument like Tajmahal is effected by air pollution, what is your advise to protect it?
Answer:
The Taj Mahal one of the seven wonders of the world is located in Agra. It is made of white marbles. The effect of pollutants like SO₂, NO₂, smoke, dust, soot, etc. on it has turned the marble from white to yellow.
Precautions to protect Taj Mahal:

1. Switch over to cleaner fuels like CNG (Compressed Natural Gas) and LPG (Liquify Petroleum Gas)
2. Use unleaded petrol in vicinity of Taj Mahal.
3. Shift polluting industries to the outside of Agra city.
4. Industrial pollution should be banned around the Taj Mahal.
5. Limited vehicular use in a specific radius.
6. An electronic board should be installed in the Taj Mahal premises, that compares current pollution levels, to the levels that deemed safe.

Question 12.
Reshma going to talk about controlling measures of soil pollution. Prepare write up for her.
Answer:
Controlling measures of soil pollution:

1. Limit the use of fertilizers and pesticides.
2. Awareness about biological control methods and their implementation.
3. The grazing of cattle must be controlled and forest management should be done properly.
4. The afforestation and reforestation must take place.
5. Proper preventing methods like shields should be used in areas of wind erosion .and wind breakes.
6. Remember to carry paper bags and minimising plastic bags.
7. The soil binding grass must be planted and the large trees must be plant along the banks.
8. Industrial waste must be dumped in the low lying areas.
9. There should be a definite technic of cropping which does not allow weeds to settle on the fields.
10. The mining waste must be improved along with the transportation.
11. The are must not be left barren and dry.

Question 13.
To conduct a quiz program on air and water pollution, prepare five thought provoking questions.
Answer:

1. What is environmental pollution?
2. What are the natural disasters of pollution?
3. What are the human activities that leads to pollution?
4. What is the unforgettable industrial tragedy took place in Bhopal on second December
5. Who is responsible for thepollution in Patancheru ? What are the interim orders, released by supreme court of India for the sake of people and environment?
6. What is the sad story of River Musi?
7. Can we save Taj Mahal from pollution?
   What is the present situation of Taj Mahal?
8. Natural resources are the devine gift for us by nature. Can we keep these resources clean and healthy for the future generations? What is your role and response towards this?

Question 14.
“Use Bicycle – Avoid motor bikes and cars”. This slogan is prepared by Sravani. Prepare some more slogans on pollution.
Answer:

1. Slogans towards biodiversity:
2. Segregate the reusable waste.
3. Don’t produce lot of waste.
4. Don’t use plastic covers.
5. Compost the wet waste.
6. Turn the waste into compost.
7. Make Compost out of fallen leaves.
8. Never burn the fallen leaves of trees.
9. Use bicycles if the destination is manageable.
10. Plant trees in vacant places and take care to ensure their growth.
11. Grow plants and protect them for fresh air and ventilation.
12. Use cattle dung, organic fertilizers.
13. Practice eco-friendly methods.
14. Strictly follow environmental policies and laws.
15. Limit the use of fire wood and use bio fuels for cooking.
16. Plant a sapling on your birthday water it every day.
17. Wash your hands, feet close to the trees and plants.

Question 15.
If you are a general manager of a chemical industry, what precautions would you take to control air and water pollution?
Answer:
Precautions to control air and water pollution :

1. Stoppage of effluent flowing into air and water bodies immediately.
2. Installing tall chimneys in factory to reduce air pollution at the ground level.
3. Installing electrostatic precipitators in the chimney of industry to reduce.
4. Plant and grow, more and more. Trees in the industry surroundings.
5. Protecting plants and trees.
6. Toxic industrial wastes should be treated chemically to neutralize the harmful substances present in it before discharging into water bodies.
7. Waste water from the industry is to be filtered first to remove particulate material and stored in shallow tanks where bacterial degradation of organic compounds takes place.

8th Class Biology 10th Lesson Not For Drinking-Not For Breathing InText Questions and Answers

Question 1.
Observe this certificate try to find out answers for the following questions.
Answer:
The pollution under control certificate

a) Which department issues the pollution under control certificate?
Answer:
The pollution check up centre issues the certificate.

b) For how much time is it valid?
Answer:
It is valid for six months.

c) For which type of vehicle has it been issued?
Answer:
Motor bike, scooters, cars, bus, lorry all type of vehicles.

d) What is emission test ? What components are tested ini the pollution check up centre?
Answer:
The test conducting of the gases releasing from the vehicle is called emission test. Components tested in the pollution check up center are carbondioxide, carbon monoxide, nitrogen, hydrocarbons, sulphur dioxide etc.

e) What will happen if carbon monoxide (CO) and hydro carbons (HQ readings are higher that the permissible limits reading ?
Answer:
If the above said gases are higher than the permissible limits reading it leads to pollution is harmful to the living organisms and hurt the health and well of living organisms.

f) Think of why there is a peed of “pollution under control certificate”?
Answer:
With a rapid increase in Ifie number of vehicles the problem of automobile pollution has assumed greater significance. The emission of smoke from motor vehicles is a major source of air pollution.

Question 2.
What will happen if harmful organisms or substances enter your body? How do you feel?
Answer:
If harmful organisms enter the body, the normal functioning of the body will be disrupted or disturbed. We feel sick.

What is air pollution ?
Question 3.
List out the gases that you know present in the air.
Answer:
The gases present in the air are nitrogen, oxygen, carbondioxide, inert gases mainly argon, and water vapour.

Question 4.
What are the four major gases in the air?
Answer:
The four major gases are nitrogen oxygen, argon and carbondioxide.

Question 5.
Draw a neat diagram showing the composition of air in the atmosphere arid write the percentage of gases.
Answer:

Question 6.
Collect the pictures of natural activities and human activities which leads to pollution and paste them in your record book.
Answer:

Question 7.
If a person burnt out types or dried leaves at a particular place. Where shall go the smoke and ash goes?
Answer:
The smoke and ash raise up, mixes with gases in the atmosphere which leads to pollution.

Water Pollution
Question 8.
Let us read the following news paper clipping.

Answer the following questions based on your understanding of the paper clipping.
a. What do you understand after reading the news paper clippings?
Answer:
Some areas in Nalgonda district, the water got polluted because of the chemicals dissolved in it. These chemicals are released Into the water by the oil factory, textiles, pesticide factory and steel factory.

b. What are the issues discussed in this news paper clipping?
Answer:
Total dissolved solids (T.D.S.) in water should be maximum 500. Due to pollution it is estimated that T.D.S. has reached to 10,000. The pollution in water is higher which is dangerous for use.

c. What are its causes and effects?
Answer:
The causes for the TDS: The chemical pollutants released by the factories into the water. Effects: The water becomes unfit for drinking. By using the water the crops are beeing dead.

d. How does the problem arise?
Answer:
Large amounts of chemicals discharged into the ground water leads to water pollution. Due to water pollution the problem arise in those areas.

e. Are you also facing this type of problems in your area? Can you explain reasons behind?
Answer:
Yes, I am facing this type problems in our area. Because industries are developed in our area. So population is increasing. That’s why water is polluted in our area.

8th Class Biology 10th Lesson Not For Drinking-Not For Breathing Activities

Activity – 1

Question 1.
NATURAL DISASTERS POLLUTION
Collect information from your school library for the following natural disasters in the world.
Answer:
Volcanic eruptions:
Deep under the earth’s surface, it’s so hot that even rock melts. Sometimes this molten rock, called ‘magma’, is pushed up to the surface. At this point it is referred to as lava. And the opening or vent that lets the lava out is a volcano. ‘
A volcano may explode violently throwing out rocks for miles around. It releases various gases and ash into the atmosphere.

Forest fires:
Forest fire is a moving combustion reaction spreading outwards in a band from it’s ignition point leaving burnt forest behind it and also called as wild fire.
It can be large uncontrolled disasters that burnt through hundred to hundred thousand acres.
Causes : Natural cause, lightening, volcanic eruptions, sparks from rocks falls and spontaneous combustion.
Pollution :
Forest fires release carbon particles (ash) into the air and pollute the air.

Sand storms and Tsunamis:
A sand storm or a dust storm is a meteorological phenomenon common in arid and semi arid regions. They arise when a gust front or other strong wind blows, loose sand and dirt from a dry surface. Particles are transported by saltation and suspension. The Sahara where sand is more prevalent, soil type than dirt or rock.
Causes:
As a force of wind passing over loosly held particles increased, the particles of sand first start to vibrate, then to saltate. As they repeatedly strike the ground, they loosen and break off smaller particles of dust, which then begin to travel in suspension.

Tsunamis:

1. Tsunami is also called as a ‘seismic sea wave’ is a series of waves in a water body caused by the displacement of a large volume of water.
2. Tsunami impact is limited to coastal areas. But their destructive power can be enormous, and they can effect entire ocean basin.
3. The 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history with, atleast 2,30,000 people killed or missing in 14 countries bordering the Indian Ocean.
4. Tsunami causes much damage by two mechanisms. The smashing force of water travelling at a high speed and destructive power of a large volume of water draining of the land and carrying away large amount of debris with it.
5. About 80% of tsunamis occur in the Pacific ocean, and there is possibility for tsunamis wherever there are large bodies of water including lakes.

Activity – 2

Question 2.
A) OIL PAPER EXPERIMENT
Answer:
Take three square pieces of white paper of 5 x 5 cm size dipped in oil. Hang these oil dipped paper at three different locations, say your backyard, your school, near a park or parking lot etc. Let it be there for 30 minutes. Observe and compare all three papers.
a) What did you found on those papers dipped in oil ?
Answer:
Some dust particles sticking to the oil paper.

b) Is there any difference observed for all the three locations ?
Answer:
Some differences are observed. The soot and ash dust particles are seen on the oil paper hung at back yard which comes from burning of wood.
More dust particles seen on the oil paper at the school and less dust particles on the oil paper which was hung near a park.

c) Try to find out the answer why this difference occurred.
Answer:
When different types of fuels are burnt they release different types of particles into air. These particles are different according to different locations.

d) Do you know where the dust particles could have come from ?
Answer:
The dust particles could have come from the effect of air pollution caused by man made resources largely affects nature.

B) HUMAN ACTIVITIES:
Name of the fuels we burnt in our daily activities including rural and urban areas.
Answer:
Petrol, diesel, wood, charcoal, tyres etc.

Activity – 3

Question 3.
POWER GENERATION PLANTS.
Go to your school library and collect information to make a list of these power generation plants and where they are located.
Answer:
THERMAL POWER PLANTS

NUCLEAR POWER PLANTS

Discuss about the adverse effects of Global warming.
Answer:
Effects of Global Warming: Global warming is having measurable effects on the planet right now. They are

1. Ice is melting in both polar ice caps and mountain glaciers.
2. Lakes around the world, including lake superior are warming rapidly.
3. Animals are changing migration patterns.
4. Plants are changing the dates of activity. Ex : Leaf flash.
5. Global warming increase in temperature around the world.
6. The average global temperature increased 0.8°C over the post 100 years.
7. Weather is changed by globed warming, some places become more hot and some more cool.
8. Global warming increases the sea level. So the costal areas will sink into the sea.
9. Ice is melted which increases the sea level that leeds to ocean acidification.

Ask your teacher about secondary pollutants why they are called so?
Answer:
Oxides of nitrogen NO, NO₂ (NOx), peroxy acetyl nitrate, formaldehyde, ozone, etc., are the secondary pollutants.
Pollutants are defined as primary pollutants resulting from combustion of fuels and industrial operations and secondary pollutants, those which are produced due to reaction of primary pollutants in the atmosphere.

Activity – 4

Question 4.
FIELD VISIT:
Visit nearby factory, industry (boiled rice mill, brick making kiln, oil mill food processing mill etc.,) present in your area and observe.

• How are they polluting air and water ?
  Answer:
  They are releasing smoke, smooth dust particles into air and releasing waste material into water sources and polluting air and water.
• Is there any green belt around the factory ? Name the trees they are growing.
  Answer:
  Ashoka, Gulmohar, Neem, Eucalyptus are growing around the factory.
•  What precautions are they taking to prevent pollution ?
  Answer:
  Suction devices known as vacuum pans are used to collect the pollutants from the water.
  To control air pollution, ventury type wet scrubber and meeting the norms described by A.P. Pollution board -have arranged.

Lab Activity 

Question 5.
POLLUTANTS:
Aim: Observation of pollutants in local available water samples.
Material: Glass tumblers, water samples from tap, pond, river, well, lake, red, blue litmus papers, soap.
Procedure: Collect water samples from a tap, pond, river, well and lake. Pour each into separate glass containers. Compare these for smell, colour pH and hardness.

• pH of water samples can be determined by using litmus paper. If blue litmus paper turns to the red colour, that water sample is acidic in nature and if red litmus turns to blue, water sample is basic in nature.
• Hardness of water can be determined using soap. If water produces lesser foam it is referred as hard water.

Observations and findings:
Record your observation in the following table.

Activity – 5

Question 6.
Visit your nearby pond/lake or river and find out the material being discharged in it. Prepare a biography on it.
Answer:
As Hyderabad has grown in size and is emerging as a global mega city, its growing water requirements have been met by under taking long distance water projects over the years. These projects are dependent on Musi River. Thousands of people depend on it for their daily needs and livelihood. The Moosi has been polluted for many years.
The people living near the Musi river, throw large quantities of garbage, untreated sewage, industrial waste, dead bodies, polythene bags, hot water and statues of deities and many other materials directly in to the river. –
The ‘Musi reservoir action plan project’ was undertaken to reduce the pollution level in the river. Pollution control activities include under the project are:

• Solid waste management.
• Installation of sewage treatment plant.
• Provision of low cost sanitary facilities.
• Development of river front.
• Efforts to develop public awareness.

Ask your teacher about aerobic bacteria and write a note on it with some examples.
Answer:
An aerobic bacteria is the one that can survive and grow in an oxygenated environment. Bacillus, nocardic and pseudomonas space aeruginosa, myobacterium tuberculosis are some of the examples of aerobic bacteria.

Do you know oil slick on sea water ?In what way it is dangerous to aquatic life?
Answer:
Several kinds of plants and animals live in oceans. Oceans maintain equilibrium in nature. We transport several kinds of oils and fuels over seas. The spillage of these oils and fuels by accident creates a layer of oil over the surface of the sea water for hundreds of kilometers. This is called oil spill or oil slog. When it happens, air and light cannot enter the sea water and several marine creatures like fish, tortoise and other marine life forms die of asphyxiation.

Think and Discuss

Question 1.
When we go on a busy road in the evening a lot of smoke is spread in the surroundings. We get cough and feel uneasy even when we close the nose with napkins.
a) Why this type of symptoms we observe? Think about it.
Answer:
Carbon monoxide is poisonous gas combines with haemoglobin of our blood and forms carboxy haemoglobin. Due to this haemoglobin is unable to carry oxygen to various parts. This leads to respiratory problems. It causes suffd&Stion and may cause even death.

b) If these symptoms will continue, what happens?
Answer:
Air pollution is like a slow poison. The effect of air pollution are not seen immediately. But over a long period of time the pollutants present in air damage our health and property.

Question 2.
Do you find any relation between pH and hardness of water?
Answer:
No relation between pH and hardness of water. pH is scale to measure acid, base or neutral hardness is the percentage of salts dissolved in the water.

Question 3.
Which water sample is colourless?
Answer:
Tap water.

Question 4.
Which water sample is suitable for drinking and why?
Answer:
Tap water is suitable for drinking because the tap water is cleaned and chlorinated and safe for drinking.

Question 5.
Do you find any change in colour and smell of water in some water samples ? What are your reasons ?
Answer:
The colour and smell of water is due to the nature of the soil and the plants grown in the water.

AP State Syllabus AP Board 8th Class Physical Science Solutions Chapter 1 Force Textbook Questions and Answers.

AP State Syllabus 8th Class Physical Science Solutions 1st Lesson Force

8th Class Physical Science 1st Lesson Force Textbook Questions and Answers

Improve Your Learning

Question 1.
What is a force? What changes can be produced by a force?
Answer:
Force: A push or a pull of an object is called a force.
Changes produced by a force:

1. A force can change the state of motion of an object.
2. A force can change the shape of an object.

Question 2.
State an example for a situation mentioned below in which a force:
a) Changes the speed of an object.
b) Changes the shape of an object.
c) Changes the direction of an object.
Answer:
a) Force changes the speed of an object:
A ball at rest begins to move when a force is applied on it that shows force changes the speed of an object.
b) Force changes the shape of an object:
Take a plastic or metal scale placed between two bricks and put some weight at the centre of the scale. We observe that force changes its shape.
c) Force changes the direction of an object:
Kick a moving football with some angle then we can observe the change in the direction of football.

Question 3.
How can you differentiate between a contact force and a force at a distance?
(OR)
Distinguish between a contact force and a force at a distance.
Answer:

Contact force	A force at a distance
1. Force which results when there is a direct physical contact between two interacting objects is known as contact force.	1. The force which occurs without any physical contact between two objects is known as a force at a distance or field force.
2. The two objects have direct contact.	2. No contact.
3. For example, the tyres of a bicycle has direct contact with the surface of the road.	3. For example, the attraction of two magnets.

Question 4.
Give two examples each for a contact force and a force at a distance.
Answer:
Contact force:
e.g.: 1) Muscular force 2) Frictional force Force at a distance:
e.g.: 1) Magnetic force 2) Electrostatic force

Question 5.
Detect the errors in the following statement and rewrite it making necessary corrections.
“Because the car is at rest, no forces are acting on it.”
Answer:
The object is said to be at rest when no forces are acting on it or net force acting on it is zero. So the statement should be corrected like this “Because the car is at rest, no forces are acting on it or net force on the car is zero.”

Question 6.
Why do tools meant for cutting always have sharp edges?
Answer:
The tools meant for cutting have sharp edges because of smaller contact area they exerts more pressure on objects and cutting of objects are easy.

Question 7.
Objects change their state of motion due to the net force acting on them. Do you agree with this statement ? Discuss with examples.
Answer:
Yes, we can agree with this statement. Net force can increase or decrease the speed of an object. Force can also change the direction of an object.
Hence we conclude that net force can change the state of motion of an object.
Some examples:

1. If we kick the ball it will move from state of rest.
2. If we stop the running ball it will come to state of rest.
3. If we through a ball on the ground it will come to rest after sometime due to gravitational force acting on it.
4. If we pull the chair, it will move due to muscular force acting on it.

Question 8.
When you push a heavy object, it doesn’t move. Explain the reason in terms of net force.
Answer:

When we apply force on a heavy object it has to overcome frictional force in order to move. If the force applied is less than the frictional force then the net force (f – F) is insufficient to move the object.

Question 9.
Find net forces from the following diagrams:

Answer:
a) Net force is 6N along horizontal direction towards right.
b) Net force is zero.
c) Net force is 14N along horizontal direction towards right.
d) Net force is 1 N upwards in vertical direction.

Question 10.
Imagine that friction has disappeared from the earth. What will happen? Explain.
Answer:
If friction has disappeared from the earth then

1. we cannot walk or run.
2. we will not have any cars or bicycles because all of them move due to friction.
3. no building could be constructed.
4. carpenters will not able to smoothen surfaces.
5. we could not fix nail on the wall.
6. it will not possible to write with pen or pencil.
7. we will not able to hold any appliances such as hammer, soap, etc.

Question 11.
Karthik is observing the live telecast of a one day cricket match. He noticed motion of a roller on the pitch during lunch break. He thought about various forces acting on the roller and the net force when it is in motion. Many questions arose in his mind regarding the direction of the net force. Can you guess what would be those questions?
Answer:

1. Why there is no motion for roller in vertical direction?
2. What are the forces acting in the vertical direction?
3. What are the forces acting in the horizontal direction?
4. Why there is motion in the horizontal direction for roller?

Question 12.
a) Take two identical straws and suspend one of them freely. Rub the other straw with a piece of paper. Bring the rubbed end of the straw near the suspended one. What do you observe from this activity? Can you tell which type of force is it?
b) Comb your dry hair. Bring the comb near small pieces of paper. What do you observe? Explain.
Answer:
a) The rubbed end of the straw attracts the suspend straw when it is brought near to it. The reason is that when the straw is rubbed with a paper, it acquires an electrostatic charge on its surface and the suspended straw near it acquires opposite charge.
b) When we comb dry hair and bring small pieces of paper they are attracted by comb the reason is when we comb dry hair, it acquires electrostatic charge and paper pieces brought near to it acquire opposite charge there by they are attracted by comb.

Question 13.
Collect pictures from various sources like internet, magazines, newspapers, etc. to illustrate contact forces, forces and prepare a scrap book.
Answer:

Question 14.
A stick is placed on steps as shown in the figure. Draw normal forces on the stick.

Answer:

Question 15.
A monkey hangs stationary at the end of the vertical vine. What forces act on the monkey
Answer:
a) The weight of the monkey downward direction.
b) The normal force by branch upward direction.
c) The frictional force exerted by branch along the horizontal direction.

Question 16.
If you push on a heavy box which is at rest, you must exert some force to start its motion. However, once the box is sliding, you can apply a lesser force to maintain that motion. Why?
Answer:
When the box is sliding, the contact points on its surface do not get enough time to lock in to the contact points on the floor. So friction is less when compared with box at rest so we required to apply lesser force to maintain motion.

Question 17.
How do you increase the pressure by keeping
(a) area unchanged and (b) force unchanged?
Answer:
Pressure P = hdg. So pressure can be depend on height of air column, density of air and acceleration due to gravity.
So pressure can be increased by increasing length of air column at a particular place and for a particular gas.

Question 18.
Design and conduct experiments to test few ways how friction may be reduced.
Answer:
Friction is due to the roughness of surfaces. It can be reduced by the following methods.
– By polishing the rough surface.
– By applying lubricants like oil and grease to the surfaces.
– By spreading powder on the rough surface like carromboard.
– By using soap and detergent solutions, etc.
Experiment: The rusted pulley makes a rattling noise. Apply some oil in between the wheel and axle. The sound is reduced and now it works smoothly.

Question 19.
Observe the figure and find in which direction the force of friction acts. Also indicate the normal forces and their directions.

Answer:

f: force of friction
N₁, N₂, N₃, N₄ are normal forces.

Question 20.
A man is standing still on a level floor. What forces act on him? Draw a free body diagram (FBD) to show all forces acting on him.
Answer:
The forces acting on the man:

Along vertical direction:

1. Weight of the man or gravitational force acting vertically downwards.
2. Normal force or reaction applied by the floor vertically up.

Along horizontal direction:
Frictional force applied by the floor on the man.

Question 21.
How do you appreciate the role of friction in facilitating our various activities?
Answer:
Every motion that occurs on earth depends upon friction. For example, we are unable to walk if there is no friction and we cannot write with a pen and we cannot construct a building and there should be no vehicles without friction.
So without friction there is no motion on earth. So friction is required for better living of human beings.

8th Class Physical Science 1st Lesson Force InText Questions and Answers

8th Class Physical Science Textbook Page No. 3

Question 1.
When an object slips off your hand, it always falls down. What pulls it down?
Answer:
Gravitational force.

Question 2.
If you roll a ball on a level ground, it slows down and after sometime it will come to a stop. What makes the ball stop?
Answer:
Frictional force acting between floor and ball.

Question 3.
What forces acting on objects, change their state or state of motion?
Answer:
Contact force and force at a distance.

Question 4.
Why does the needle of a magnetic compass move when we place a bar magnet near to it?
Answer:
A force at a distance or field force acts on the needle. So, the needle of a magnetic compass moves when we place a bar magnet near it.

Question 5.
Why does the toothpaste come out when we press the tube?
Answer:
A contact force acts between our hand and tube. So, the toothpaste comes out when we press it.

Question 6.
Have you observe the difference between the force applied by a magnet on the needle of a compass and the force you applied on the tube?
Answer:
First one is force at a distance and the second one is contact force.

8th Class Physical Science Textbook Page No. 4

Question 7.
If a pen slips off from our hands it falls down to the floor.
a) Why does the pen fall down ?
b) What is the force which pulls the pen down ?
Answer:
a) Due to increase of gravitational pull of the earth than the normal force,
b) Gravitational pull of the earth.

Question 8.
If we keep the pen on a table, it does not fall down. Why ?
Answer:
As the normal force and gravitational pull of the earth are equal, it does not fall down.

Question 9.
a) Why does a stone thrown up into the sky fall back to the earth?
b) Why do rivers flow down to the sea?
c) How does the earth hold the atmosphere?
d) Is there any force pulling the objects towards earth?
Answer:
For all the above questions, the answer is ‘due to gravitational pull of the earth on the nearer bodies of the earth’.

8th Class Physical Science Textbook Page No. 6

Question 10.
In all the actions that we perform in our daily life like brushing, bathing, eating, writing, driving and walking ; we have to exert a force. Do you know from where the force comes?
Answer:
The force comes from our muscles.

8th Class Physical Science Textbook Page No. 8

Question 11.
Did you ever experience slipping on a floor? What conditions caused you to slip?
Answer:
Yes, it was due to less friction between my foot and floor.

Question 12.
Did you experience slipping while you are walking on wet mud ? Why do most of road accidents happen during rainy days?
Answer:
Yes, in the wet mud the friction is very less and wet mud acts as a lubricant between our feet and floor. During rainy season the mud or road will be wet and as mentioned above the friction will be less, so most accidents happen.

Question 13.
Would it be possible to drive a car if there were no friction between the tyres and the road?
Answer:
No, we can’t stop the car as there is no friction in case of no friction between the tyres of car and the road. We can drive, but the car would not get any control.

Question 14.
Place your science book on the table. Is it in a state of rest?
Answer:
Yes.

8th Class Physical Science Textbook Page No. 9

Question 15.
What is the state of the stone?
Answer:
At rest.

Question 16.
What forces are acting on it?
Answer:
Tension and gravitational pull of the earth.

Question 17.
What will happen if the thread is broken?
Answer:
The gravitational pull of the earth increases and the stone falls down.

Question 18.
What do we call this force ? (the force supporting the stone)
Answer:
Tension.

8th Class Physical Science Textbook Page No. 13

Question 19.
You might have seen children playing with a rubber tyre by pushing it with a stick.
They push the tyre again and again with the stick to increase its speed,
a) Do you understand why the speed of the tyre increases whenever it is pushed by the stick?
Answer:
With every push they are applying a little more force on the moving tyre in the direction of motion. Hence the speed of the tyre increases continuously.
b) Give some more examples where the object speeds up or slows down or a change may occur in its direction of motion, when we exert a force on it?
Answer:
If wind blows in the direction of motion of bicycle the speed of bicycle increases. If wind blows in the opposite direction of motion of bicycle the speed of bicycle decreases.

Think and Discuss

8th Class Physical Science Textbook Page No. 5

Question 1.
A cricket ball of mass’m’ is thrown upward with some initial speed. If the air resistance is neglected, what forces are acting on the ball when it reaches (a) half its maximum height and (b) its maximum height?
Answer:
The forces which are acting on the ball thrown vertically upward:
a) At half of its maximum height:

1. The remaining force which acts vertically upwards (some force that we applied is utilized in reaching half of maximum height).
2. The gravitational force downwards.

b) At maximum height:
Gravitational force acts downward direction (The applied force is completely utilized in reaching maximum height).

8th Class Physical Science Textbook Page No. 6

Question 2.
Two identical bars, one which is steel and the other a magnet, are painted with the same colour. How can you tell which one is the magnet using only these two bars? (don’t break the bars)
Answer:
The bar which attracts the other bar is magnet. The other bar is magnetic material that is steel.

8th Class Physical Science Textbook Page No. 8

Question 3.
A book placed on a table is at rest. Is the force of friction acting on it or not ? Explain.
Answer:
Friction is caused by the irregularities on the two surfaces in contact. Even those surfaces which appear very smooth have large number of minute irregularities on them. Irregularities on the two surfaces lock into one another. So a book placed on a table is at rest experiences frictional force.

8th Class Physical Science Textbook Page No. 10

Question 4.
A system of two bodies A and B are placed as shown in figure. How many forces are acting on A and B respectively?
Answer:

On A

1. Normal force exerts by floor vertically upwards.
2. Weight of A vertically downwards.
3. Frictional force exerts floor along horizontal direction.

On B

1. Normal force exerted by surface of A vertically upwards.
2. Weight of B vertically downwards.
3. Frictional force exerts by surface of A along horizontal direction.

Question 5.
Why is it necessary to separate contact force into a normal force and frictional force? Give at least two reasons.
Answer:
Reasons:

1. In order to know what are the forces acting on the object.
2. To know the net force acting on the body.
3. To know the direction of motion of an object.

8th Class Physical Science Textbook Page No. 12

Question 6.
Play arm wrestling with your Mend. How can you explain the winning of the game by using the concept of net force?
Answer:
The person we exerts more muscular force tends to win.

Question 7.
Name the forces acting on arm and their direction while playing the game. Try to draw FBD for this situation.
Answer:
The muscular force, normal force and weight (gravitational force).

8th Class Physical Science Textbook Page No. 15

Question 8.
Does pressure have direction? Explain.
Answer:
Pressure exerts in all directions. So there is no specified direction for pressure. So we does not consider pressure has direction i.e., it has only magnitude but not direction. So it is a scalar quantity.

8th Class Physical Science 1st Lesson Force Activities

Activity – 1

Question 1.
Identifying push or puli:
Write push or pull in the blank boxes given below. If you feel that the action involves both push and pull, write both in the boxes.
Answer:

a) List three more activities where we exert force which appears as a push.
Answer:

1. Pushing a repaired car.
2. A football player taking a penalty kick.
3. A cricket ball hit by a batsman.

b) List three more activities where we exert a force as a pull.
Answer:

1. Drawing bucket of water from a well.
2. Opening a drawer.
3. In a game of tug of war, two teams pull the rope in the opposite directions.

c) State three actions which involve both push and pull.
Answer:

1. Moving a book front or back on a table.
2. Opening or shutting a door.
3. Cleaning the floor with a cloth.

d) Shall we call the effort done on an object by means of pushing or pulling as a force exerted on the object?
Answer:
Yes, it is called force.

e) When an object slips off your hand, it always falls down. What pulls it down?
Answer:
Gravitational force.

f) If you roll a ball on a level ground, it slows down and after sometime it will come to a stop. What makes the bail stop?
Answer:
Frictional force acting between floor and ball.

g) What forces acting on objects, change their state or state of motion?
Answer:
Contact force and force at a distance.
Types of forces:

h) Why does the needle of a magnetic compass move when we place a bar magnet near it?
Answer:
Due to magnetic force of magnet.

i) Why does the toothpaste come out when we press the tube?
Answer:
Due to muscular force applied by us on toothpaste.

j) Have you observe the difference between the force applied by a magnet on the needle of a compass and the force you applied on the tube?
Answer:
First one is force at a distance and the second one is contact force.

Activity – 2

Question 2.
Observing the magnetic force :
Take a sewing needle. Rub it with a bar magnet several times always moving the magnet in the same direction.
a) Does the needle get magnetised?
Answer:
Yes. Identify south and north pole of the magnetised needle. Pin a red coloured foam ball to South pole and white ball to North pole of the needle, then drop it in a bowl of water it floats.
Make another needle in the same way. Float both the needles side by side such that like ends facing each other.

b) What happens to the needles? How do they move?
Answer:
They repel each other. They move backwards to each other.

c) Now place the needles in such a way that unlike ends face each other. How do they push or pull each other?
Answer:
They pull each other that means they are attracted.

d) What is this pull or push between two poles called?
Answer:
Magnetic force.

Activity – 3

Question 3.
Observing electrostatic forces :
Take a balloon. Inflate it and tie up the open end. Now cut a paper into small pieces and place them on floor. Rub the balloon with a paper and using the balloon near the pieces of the paper.
a) Are the bits of paper pulled towards the balloon?
Answer:
Yes, the bits of papers pulled towards balloon.

b) Why does the balloon pull or attracts the pieces of paper?
Answer:
When the balloon is rubbed with a paper it acquires charge and it induces opposite charge which brought near to it. So the pieces of paper are attracted by balloon.

c) Try to use pepper and salt in the place of pieces of paper. What do you observe?
Answer:
They do not attracted by the balloon.
Gravitational force: It is our common experience that if a pen slips off from our hands it falls down to the floor.

d) Why does the pen fall down?
Answer:
Some force is acting in downward direction.

e) What is the force which pulls the pen down?
Answer:
Gravitational force exerted by the earth.

f) If we keep the same pen on a table, it does not fall down. Why?
Answer:
The gravitational force exerted by earth is balanced by normal force between pen and surface of the table.

g) Why does a stone thrown up into the sky fall back to the earth?
Answer:
Due to gravitational pull.

h) Why do the rivers flow down to the sea?
Answer:
Due to gravitational force exerted by earth.

i) How does the earth hold the atmosphere?
Answer:
Due to gravitational force exerted by earth.

j) Is there any force pulling the objects towards earth?
Answer:
The force exerted by earth is gravitational force.

k) Where does gravitational force exists?
Answer:
The gravitational force exists everywhere in the universe between the objects having masses.

Activity – 4

Question 4.
Visualizing magnetic field:

Take a bar magnet and place it on a table. Place a thick white paper over it.
On the paper, sprinkle fine powder of iron as shown in the figure. Tab the table or the paper gently with pen/pencil.
a) Do you find the pattern of iron filings there?
Answer:
Yes.

b) Rotate the magnet in different directions and do the same. How has the pattern changed?
Answer:
In different directions that we will observe different patterns.

c) Why the iron filings set pattern around magnet?
Answer:
Iron filings set themselves in a pattern because of magnetic field created by the magnet.

d) What is the space around the magnet called?
Answer:
The space around magnet where its influence can be detected is called magnetic field.

Activity – 5

Question 5.
Preparing a list of examples for muscular force:
List at least ten activities where we apply muscular force to perform various tasks in table.
Answer:

List of activities where we exert force

Lowering a basket

Lifting a bucket from a well

Pushing a car

Pulling a cow

Opening a drawer

Opening or shutting a door

Hitting a cricket ball with a bat

Playing badminton

Digging a bore well

Raising a flag

Activity – 6

Question 6.
Observing the changes in any muscle while working:
Do you feel your muscle get tightened while performing a physical activity? What could be the reason for it?
Answer:
Take a dumbbell and lift it in different ways and observe while doing this exercise which muscle is going to be shortened.
The term muscles refer to multiple bundles of muscle cells held together. Muscles are normally arranged in such a way that, as one group of muscles contract or shortens, another group relaxes or expands. So we feel the muscles get tightened while performing any physical activity.
Force of friction:
When you roll a ball on a level ground it invariably stops after sometime.
a) Why does the ball stop?
Answer:
Due to some opposing force.

b) Is there any hidden force which brings it to stop?
Answer:
Frictional force between floor and ball.

c) If you stop peddling your bicycle on a level road you observe that its speed decreases gradually. Why does the speed of bicycle decrease gradually? Is there any force acting on it which tends to reduce its speed?
Answer:
The speed of bicycle decreases gradually due to some opposing force. The force is frictional force between road and tyre.

Activity – 7

Question 7.
Observing the motion of a ball on different surfaces.
Try to roll a ball on different surfaces like carpet, rough roads, smooth floor, etc. On which surface does the ball roll farther ?
Answer:
On the smooth floor it roll farther the reason is the force of resistance to the motion seems to be more on the rough surfaces than on the smooth surfaces.

Activity – 8

Question 8.
Observing the motion of objects on an inclined plane:
Take a tray. Place a small ice cube, eraser and a rupee coin to stay on a line at one end of the tray. Now slowly lift this end of the tray as shown below.

a) What do you observe?
Answer:
The three objects tends to slide downwards.

b) Which of these three objects slides down first? Why?
Answer:
Ice cube rolls first because the melting of ice takes place
and water acts as lubricant and decrease the frictional force.

c) Do all objects experience the same resistance to motion? If not why?
Answer:
No, all of them does not experience same resistance in motion because the irregularities present in the surfaces of the objects are different.

d) Which of the objects experiences more resistance to motion? Why?
Answer:
The eraser experiences more frictional force due to more normal force exerted on the surface of eraser.

e) Why the change in resistance experienced by the objects though they all slide down on the same plane?
Answer:
The frictional force depends on nature of surface. So different surfaces exerts differed frictional forces, therefore there is a change in resistance.

f) Did you ever experience slipping on a floor?
Answer:
Yes.

g) What conditions caused you to slip?
Answer:
When we walk on a smooth floor.

h) Did you experience slipping while you are walking on wet mud?
Answer:
Yes.

i) Why do most road accidents happen during rainy days?
Answer:
Rain water acts as lubricant which decrease the frictional force between tyre and road thereby vehicles slip more due to that accidents occur more on rainy days.

j) Would it be possible to drive a car if there were no friction between the tyres of car and the road?
Answer:
No, it is not possible.
Normal force:

k) Place your science book on the table. Is it in a state of rest?
Answer:
Yes.

l) Is there any force acting on that book?
Answer:
Yes.

m) Imagine that the table has disappeared suddenly by magic. What will happen then?
Answer:
The book will fall down due to gravitational pull of the earth.

n) When a book is lying on the table, the gravity pulls the book down all the time but it does not fall down. Why?
Answer:
It is supported by the table.

o) What is the force which supports against gravity by pushing it upward called?
Answer:
The force that a solid force exerts on any object in the normal direction is called the normal force.
Tension:
As shown in the figure a stone is suspended with the help of a thread and its free end is tied to the ceiling.

p) What is the state of the stone?
Answer:
The stone is at the state of rest.

q) What are the forces acting on it?
Answer:
Gravitational force acts downwards and the force exerted by string acts upwards.

r) What will happen if the thread is broken?
Answer:
The stone will fall downwards due to gravitational pull.

s) For a stone tied to the thread there exists a force which supports the stone against gavity by pulling upwards. What do we call this force?
Answer:

It is called tension.

t) What is tension?
Answer:
When we stretch a rope or a thread the tightness of rope or thread is called tension. Tension is a contact force.

Lab Activity

Write an activity to measure limiting force beared by a thread:
(OR)
Conduct an experiment to find the limiting force that can be borne by different threads.
Answer:
Aim: To find the limiting force that can be borne by a thread.
Material used: Spring balance, weights, light threads, weight hanger.
Procedure:
i) Arrange the system as shown in figure. Put some small weights like 50 gm on the weight hanger and note the readings of the spring balance. Now, add some more weights to the hanger and note the readings of spring balance. Do the same till the thread is broken.

ii) Separate the whole system from the ceiling, and tie the thread to weight hanger and now slowly pull up the whole system with your hand when there is a small weight on the hanger.
Note down the readings of the balance when the thread is broken that give limiting force beared by a thread.

a) What do you observe from the readings when it pulled up and released to move down?
Answer:
We will observe from the readings that another force is worked on this system when it is pulled up and released move down.

b) Is the thread broken when the whole system is pulled quickly up?
Answer:
No, the thread is not broken when the whole system is pulled quickly up.

Net force:
a) What are the forces acting on an object placed on a floor?
Answer:
Gravitational force (vertically down) and normal force (vertically up).

b) Do you observe any change in the state of rest of that object, because of these forces and why?
Answer:
No, because these forces acting on the object are equal and opposite in direction. Hence there is no change in its state.

c) What is the net force acting on object in this case?
Answer:
Zero.
Imagine that the same object is kept in a lift which is accelerating.

d) How many forces are acting on this object?
Answer:
Weight of the object (vertically down) and accelerating force (vertically up).

e) Is the net force acting on the object zero? Why?
Answer:
No, it is not equal to zero because the object is moving upward with non-uniform motion.

Activity – 9

Question 9.
Effects of net force acting on a table :
a) Try to push a heavy wooden table. Is it hard to push ?
Answer:
Yes.

b) Ask your Mend to help in pushing the table in the same direction, as shown in the figure. Do you find it easier to move the table now? Why?

Answer:
Yes, because both of us applying force in the same direction on the table. So resultant applied force increases so it is easier to move the table.

c) Now ask your Mend to push the table from the opposite side as shown in the figure.

Does it move ? If it moves, then in which direction does it move?
Answer:
If both of us apply same force with equal magnitude the table does not move.
If it moves, it moves in the direction where there is larger force is applied.

d) If we apply two unequal forces F₁, F₂ applied in the same direction and opposite direction (F₁ > F₂) then what is the net force ?

Answer:

If F₁, F₂ act in same direction, net force = F₁ + F₂
If F₁, F₂ act in opposite direction, net force = F₁ + (-F₂) = F₁ – F₂

Activity – 10

Question 10.
Effects of stretched rubber bands on fingers:
Take a rubber band, stretch it using your fingers. When you stretch the rubber band it exerts force on your fingers and you feel the force of pull on your fingers.
a) What happens if you add one more similar rubber band around your fingers and stretch both together to the same length ? Do you feel the combination of two bands exerts a larger force than that of one?
Answer:
Yes, the net force is the combination of two forces. So they exerts larger force.

b) Let us say the force exerted by one rubber band is F units and the force exerted by the second rubber band is also F units. Then what will be the net force of two rubber bands?
Answer:
Net force (F_net) = F + F
= 2F units

c) What is the net force acting on your finger when three, four, etc. rubber bands are used?
Answer:
If three rubber bands are used the net force = F + F + F = 3F
If four rubber bands are used the net force = F + F + F + F = 4F

How to calculate net force from free body diagrams:
Let a car moving with non-uniform speed along a road.
What are the forces acting on the car? What is the net force acting along the vertical direction? What is the net force acting along horizontal direction? Draw all the relevant forces acting on the body by using free body diagram.
Choose a coordinate system with X and Y axis in figure. Sign convention is to be taken along X and Y directions. Add forces algebraically with sign conventions along X and Y axis respectively.
Answer:

The forces acting on the car are, shown in FBD (Free body diagram).
They are Force applied by the engine = F
Friction applied by road = f
Normal forces are N₁ and N₂.
Gravitational force (F_g) = W
∴ Net force along X – direction,
F_{net, x} = f – F
(∵ They act in opposite direction)
Net force along Y – direction,
F_{net, y} = (N₁ + N₂) – W
(∵ They act in opposite direction)

Activity – 11

Question 11.
Effect of force on the direction of motion and state of the body:
Place a football on the ground. The ball will remain in the state of rest unless someone kicks the ball.

a) Kick the ball what happens? Does the ball start moving?
Answer:
Yes, the ball start moving

b) Kick the moving ball again in the same direction.
What will be the result?
Answer:
The speed of the ball increases.

c) Place your hand or leg against the ball. Does the ball stop ?
Answer:
Yes. You might have seen children playing with a rubber tyre by pushing it with a stick. They push the tyre again and again with the stick to increase its speed.

d) Do you understand why the speed of the tyre increases whenever it is pushed by the stick?
Answer:
With every push they are applying a little more force on the moving tyre in the direction of motion. Hence speed of the tyre increases continuously.

e) What happens if net force acts opposite to the motion of an object ?
Answer:
The net force acts opposite to the direction of motion of an object then it either slows down the object or brings it to a stop.

f) Give some more examples where the object speeds up or slows down or a change may occur in its direction of motion, when we exert a force on it?
Answer:
If wind blows in the direction of motion of bicycle, the speed of bicycle increases. If wind blows in the opposite direction of motion of bicycle, the speed of bicycle decreases.

Activity – 12

Question 12.
Effects of net force on direction of moving object:

a) Hit a carrom coin with the striker. Ask your friends to do the same. Does the coin move in the same direction in each case ?
If not why?
Answer:
No, you can observe that when you hit the coin with the striker not only does the coin changes its direction, but the striker changes its direction too.

b) What might be the cause of that?
Answer:
The net force makes a stationary object move and also changes the speed and direction of moving object.

c) Does the force change only the state of motion ? Are there any other effects of force?
Answer:
No, the force changes the direction.

Activity – 13

Question 13.
Effects of force on the shape of an object:
In the given table some situations are given in the first column showing how the force is applied on an object. Observe the shape of the objects carefully before and after applying the force. Mark T for temporary change and ‘P’ for permanent change.
Answer:

Action of force	Change in shape (temporary / permanent)
Stretching rubber band	Temporary
Squeezing sponge	Temporary
Tearing paper	Permanent
Crushing plastic bottle	Permanent
Making chapathi	Permanent
Breaking glass	Permanent

Activity – 14

Question 14.
Change in effect of force with area of contact:
a) Take a pencil. Just push its rounded end on your palm. Now push from the other side of the pencil gently so that the sharp end is on your palm. What difference did you experience? Why?
Answer:
It applies more force when sharp end touches the palm.

b) Why do the porters place turbans (talapaga) on their head when they have to carry heavy loads?
Answer:
The reason is, they are increasing surface area there by they are decreasing the force applied by object.

c) Why do school bags and shopping bags have broad straps as handles?
Answer:
As the surface area increases the force applied by object decreases.

d) Have you ever wondered why the lorries carrying loads have a large number of broader tyres?
Answer:
The effect of force depends on the area of contact on which the force is acting. When the area of contact is more then the force acting is less. So lorries have a large number of broader tyres to carry heavy loads.

Activity – 15

Question 15.
Identifying effects of force:
Take two trays. Fill both the trays with lime powder or fine sand. Now take two rectangular bricks of equal mass and similar shape. Keep one brick vertically in one tray and the other brick horizontally in the second tray.
a) Do both bricks sink to the same depth in lime powder? If not why?
Answer:
No, both does not sink to the same depth. The brick standing vertically sink deeper in lime powder than the brick standing horizontally The reason is the contact area or surface area on which force is acting is smaller and hence pressure exerted by the brick is more.

b) Why does the sharper side of a knife cuts more easily than a blunt side of it?
Answer:
A sharper side of knife has a smaller contact area. Therefore sharper side of knife exerts more pressure than the blunt side.

AP State Syllabus AP Board 8th Class Physical Science Solutions Chapter 4 Synthetic Fibres and Plastics Textbook Questions and Answers.

AP State Syllabus 8th Class Physical Science Solutions 4th Lesson Synthetic Fibres and Plastics

8th Class Physical Science 4th Lesson Synthetic Fibres and Plastics Textbook Questions and Answers

Improve Your Learning

Question 1.
Explain why some fibres are called synthetic.
Answer:
Unlike natural fibres, synthetic fibres are made from petroleum based chemicals or petrochemicals. Petrochemicals are subjected to various chemical processes to obtain synthetic fibres. Due to this they are called artificial fibres or synthetic fibres.

Question 2.
Give reasons why plastic containers are used as storage devices.
Answer:
Plastic containers are used as storage devices because

1. They are non-reactive: Metals like iron get rusted when they left exposed to moisture and air. But plastic do not react with water and air. So they are not corroded easily.
2. Plastic is light, strong and durable: Plastics are very strong, light and durable can be moulded into different shapes.
3. Lower price: Plastics have relatively lower price when compared with metals.

Question 3.
Classify following materials which can be, cannot be recycled.
Plastic toys, electrical switches, plastic chairs, ball point pens, plastic containers, cooker handles, plastic bottles, carry bags, tumblers, tooth brush, plastic chapels, plastic plates, plastic buckets.
Answer:

Plastic toys	–        recycled
Plastic chairs	–        recycled
Ball point pens	–        not recycled
Tooth brush	–        not recycled
Cooker handles	–        not recycled
Plastic containers	–        recycled
Plastic bottles	–        recycled
Carry bags	–        not recycled
Tumblers	–        recycled
Electrical switches	–        not recycled
Plastic chapels	–        recycled
Plastic plates	–        not recycled
Plastic buckets	–        recycled

Question 4.
If electric switches are made by thermoplastics what would happen?
Answer:
Thermoplastics are become soft on heating and they can change their shape. Heat developed due to electricity may change the shape of switches and they become soft whereas thermosetting plastics once moulded does not change their shape and they comparatively bad conductors of heat and electricity than thermoplastics. So thermo-plastics are not preferable in making of electrical switches.

Question 5.
Thermoplastics are ecofriendly than thermosetting plastics. What do you say? Why?
Answer:
Yes, they are ecofriendly when compared with thermosetting plastics. The reason is plastics are non-biodegradable material. Land filling of plastic and burning of plastic in incenerators are the ways of disposal of plastic. These two ways are harmful to environment. The better method is recycling of plastic. Which is possible with only thermoplastics and thermosetting plastics cannot be recycled. Therefore we consider thermoplastics as ecofriendly.

Question 6.
Explain the following.
a) Blending
b) Biodegradable
c) Recycling
d) Decomposition
Answer:
a) Blending: Any synthetic fibre can be combined with two or more other fibres is called blending. Natural and synthetic fibres are often blended for preparing better fabric.
When first fibre is blended with second fabric it gives us a blended fabric which possess the best quality of both.
Eg: We know cotton wearing is comfortable and polyester is wrinkle free. When cotton and polyester blend the end result of fabric formed is comfortable and wrinkle free.

b) Biodegradable: A material which is easily decomposed by natural process is called biodegradable. Eg: Vegetables, fruits, paper, cotton, clothes, woolen clothes, etc.

c) Recycling: Recycling is a process of conversion of broken plastic material into new plastic products.

d) Decomposition: Certain materials can break down in to smaller fragments in the presence of water, sunlight and oxygen. These fragments get further broken down by bacteria. This is called decomposition.

Question 7.
Match the following.
Group – A                              Group – B
1. Polyester        ( )          A) Kitchenware
2. PET                 ( )          B) Artificial silk
3. Rayon             ( )          C) Many monomers
4. Nylon             ( )          D) Electric switches
5. Melamine       ( )          E) Code 1
6. Polyethene     ( )          F) Popular dress material
7. Bakelite          ( )          G) Stronger than any fiber
Answer:
1) F
2) E
3) B
4) G
5) A
6) C
7) D

Question 8.
Fill in the blanks.
i) Synthetic fibres are called as …………….. fibres.
ii) Synthetic fibres are synthesized from raw material called ……………. .
iii) Like synthetic fibre, plastic also ……………… .
iv) Clothing labels are
A) Required by law
B) Identify fabric content
C) Both A and B
D) None of the above
v) Rayon is made of
A) Coal
B) Oxygen
C) Flax
D) Cellulose
vi) A silk fibre’s smooth surface absorbs light
A) Yes
B) No
C) Can’t say
Answer:
i) artificial
ii) petrochemicals
iii) Polymer
iv) B) Identify fabric content
v) D) Cellulose
vi) B) No

Question 9.
Where do we use the process of recycling? How is it useful? Give examples.
Answer:
The process of recycling is useful for plastic which are non-biodegradable material. The broken plastic material articles collected from the households and send it for recycling. From this recycled plastic new products are prepared after giving it a proper treatment.
e.g.: Pet bottles, plastic carry bags, coffee cups, egg boxes.

Question 10.
Prepare a table of various synthetic fibers which are used to make household articles from them.
Answer:

Synthetic fibre	Household item
Nylon	It is used in most hosiery articles such as stockings. Also tooth brush bristles, ropes, tents, sarees, socks, car seat belts, sleeping bags, curtains, carpets, fishing nets, etc.
Synthetic fibre	Bead necklace, paper clip, paper clip, chain, etc.
Rayon	It is used to prepare sarees, bed sheets, carpets, fashion and home furnishings, sanitary products, diapers and bandages and lints for dressing wounds, etc.
Acrylic	It is used in knitted apparels such as fleece, socks, sportswear and sweaters. It is also used in craft yarns, upholstery fabrics, carpets, luggage awnings and vehicle covers, etc.
Polyesters	Polyester is used to make dresses, PET bottles, utensils, fibres, wires etc.
Polyesters	Polyester is made by reacting dicarboxylic acid with dihydric alco­hol.
Nylon	Nylon is made of chemical units called polyamides (carbon, oxygen, nitrogen)
Rayon	The cellulose collected from plants is treated with sodium hydrox­ide, carbon disulphide and into dilute sulphuric acid.
Acrylic	It is made from the combination of coal, air, water, oil and limestone.

 

Question 11.
Explain the differences between the thermoplastics and thermosetting plastics with the help of a diagram explaining in terms of arrangements of monomers.
Answer:

Question 12.
Introduction of synthetic fibres in the textile industry brought revolutionary change across the world in the dressing patterns irrespective of culture and customs. How do you appreciate this?
Answer:
Synthetic fibres are used everywhere in the world due to their specific characteristics that is they are durable, less expensive, readily available, affordable and are easy for maintenance. So they are decreasing the boundaries of races. So synthetic fibres are one of the factor which make the people unite irrespective of culture and costumes.

Question 13.
How synthetic fibres changed our everyday life?
Answer:
Synthetic fibres are more comfortable and wrinkle free. They does not shrinks. They exists in different colours. They are less expensive. They absorb less water and dry at a faster rate. They exists in different designs. They are durable and readily available. Different synthetic fibre clothes are available for different seasons. Now synthetic fibres are essential part of our life. So synthetic fibres changed our life.

Question 14.
Nibha wants to buy clothes to parents for winter wear. What type of clothes would you suggest? Specify reasons.
Answer:
We would suggest clothes made of acrylic. The reason is it is affordable and accessible. It is cheap and easily available. It has all the characteristics of wool so considered as artificial wool. So it is preferable to wear clothes made of acrylic in winter.

Question 15.
If plastic is not properly disposed, what could be the consequences?
Answer:
Plastics take several years to decompose. Slow decomposition of plastics causes environment pollution. The polythene bags thrown around are responsible for clogging drains. The animals in urban areas are dying due to eating of polythene bags containing food material. They not only posed a great threat to nature and environment but also to the human race itself. The burning process of plastic is also very slow and cannot be burnt completely. The process of burning release a lot of poisonous fumes in to air causing air pollution. So plastics should be properly disposed that is recycling process is used.

Question 16.
Indiscriminate usage of plastic is a serious threat to bio-diversity. What are the efforts of government and non-government organization in this regard?
Answer:
Efforts of government and non-government organisation:

1. Andhra Pradesh based NGO’s drawing court attention that 30 – 60 kg of plastic bags recovered from the stomache of cows.
2. Private institutions in Kozikode, Kerala fighted against plastic wastes and their consequences on environment.
3. Government has burned plastic carry bags less than 40 microns.
4. Many non-government organisations are giving publicity about the harmful effects of plastics. They are encouraging people to use bags made of cotton.
5. Various non-government organisations are collecting plastics from households and send it for recycling.
6. Government is planning to solid plastic waste into resources such as electricity, heat, compost.

Question 17.
Take hair, wool, silk, paper, cotton thread, piece of plastic, thread of sweater, piece of rope and carefully conduct a flame test. Based on smell and type of melting classify them as natural or artificial fibres.
Answer:
If they burn with black deposit of carbon then the fibres are natural. If they melt they are artificial fibres.

Fibre	Natural / Artificial
1. Hair	Natural
2. Wool	Natural
3. Silk	Natural
4. Paper	Natural
5. Cotton thread	Natural
6. Piece of plastic	Artificial
7. Thread of sweater	Natural
8. Piece of rope (Plastic)	Artificial

Question 18.
Prepare a chart which can explain recycling codes, full name and acronym of plastic and its usage for various household articles, recycled or not, if recycled what will be made from that?
Answer:
Recycle code symbols:

8th Class Physical Science 4th Lesson Synthetic Fibres and Plastics InText Questions and Answers

8th Class Physical Science Textbook Page No. 45

Question 1.
Are all of our clothes made of natural fibres?
Answer:
No, there are two types of fibres. They are natural fibres and synthetic fibres. Nowadays we make up artificial fibres from natural fibres by adding petroleum products.

8th Class Physical Science Textbook Page No. 46

Question 2.
What do you know about synthetic fibres? How are they manufactured?
Answer:
The artificial fibres obtained from plant or animal source are called synthetic fibres. They are made by the raw materials obtained from petroleum, e.g.: Polyester, nylon and acrylic.

Question 3.
What does polymer mean?
Answer:
The word polymer was derived from Greek. Poly means many and mer means part/unit.

8th Class Physical Science Textbook Page No. 53

Question 4.
Why are soft drinks stored in PET bottles?
Answer:
Soft drinks are carbonated so they are stored in PET bottles which are non-reactive with carbonated drinks.

Think and Discuss

8th Class Physical Science Textbook Page No. 46

Question 1.
What made the human beings to search for the alternative for natural fibres?
Answer:
Human beings used to wear clothes made by natural fibres like cotton, wool, silk, etc.
They do not have uniform thickness, they are costly, less durable, not readily avail¬able, they are not wrinkle free, they do not have water proof, they are not lustrous. So in order to avoid these advantages of natural fibres human beings made search for alternative for natural fibres.

Question 2.
Which fibre source is not exhaustible? Why?
Answer:
Natural fibre source is not exhaustible because they are made from plants and animals. Where as artificial fibres are made from petrochemicals which are exhaustible.

8th Class Physical Science Textbook Page No. 47

Question 3.
How synthetic fibres evolved to the present position?
Answer:
Synthetic fibres are cheap, durable, readily available, wrinkle free, they are affordable and easy maintenance made them to evolve the present position.

8th Class Physical Science Textbook Page No. 49

Question 4.
If we use cotton cloth and cotton ropes in preparing a parachute, what will happen?
Answer:
Cotton thread does not resist to higher weights. So the rope breaks. So it is not preferable to use cotton cloth and cotton rope in preparing parachutes.

Question 5.
Traditionally fishermen used cotton nets. Now they are using nylon nets. What is the advantage of using nylon nets?
Answer:
Cotton does not resist to higher weight and it is not strong. It is easily breakable with small weights. So nowadays fisherman are using nets which are made of nylon which resist to higher weights and are strong.

Question 6.
Nylon sarees are much better than the cotton sarees. It is better to use only nylon sarees. Do you agree with this ? Why?
Answer:
Nylon fibre is strong, elastic and light weight. Cloth made of nylon are lustrous and easy to wash. Nylon does not absorb water. So in general nylon clothes are better than cotton clothes but it has some limitations that is static electricity is easily created in nylon fabric. It also easily catches to fire and nylon clothes stick to human body so we should not wear nylon clothes while cooking, welding or working near a fire or using heavy machineries. So wearing nylon sarees always is not preferable.

8th Class Physical Science Textbook Page No. 50

Question 7.
What characteristics make rayon better than natural silk?
Answer:
Artificial rayon is cheaper than silk and can be woven like silk fibre. It can be dyed in a wide variety of colours. So artificial rayon is better than natural silk.

Question 8.
If you want to purchase a doormat made of synthetic fibre, which synthetic fibre doormat will you select? Why?
Answer:
We would prefer nylon for door mats because it is strong, elastic, cheap, easy to wash, does not absorb water and lustrous.

Question 9.
If sanitary diapers and bandages are made up of nylon, what will happen?
Answer:
Nylon fibres are strong. So they are difficult to cut. So they are not preferable for sanitory diapers and bandages.

8th Class Physical Science Textbook Page No. 51

Question 10.
Which type of blended fabrics do you find more comfortable in winter? Why?
Answer:
We would find terriwool are more comfortable in winter. The reason is terriwool is similar to wool so protect us from cold.

Question 11.
The fabrics namely natural, synthetic and blended are available for garments. Which fabrics will you prefer to wear for rare occasions like functions and in routine? Why?
Answer:
We will prefer to wear blended fabric in rare occasions like functions because it possess best qualities of natural and artificial fibre. Generally we will prefer artificial fibre because it is cheap, durable and easily available.

8th Class Physical Science Textbook Page No. 52

Question 12.
Which fabric do you prefer? Natural or synthetic? Why? Discuss comparatively.
Answer:
We would prefer synthetic clothes generally because they are durable, less expensive, readily available, affordable, they absorb less water and dry at faster rate, they are lustrous and they are easy for maintenance. But we would not prefer for synthetic clothes for those who are working in the kitchens and laboratories. The reason is synthetic fibres are easily catch fire and the fabric melts and sticks to the body of the person who wears it.

Question 13.
What is the difference between washing of clothes at home and washing by dry cleaning at laundary?
Answer:
At home for washing of clothes we use detergent or washing powder and water. Whereas dry cleaning is the process conducted in the absence of water for those clothes which should not be washed with water. So in laundry dry cleaning is carried out by using organic liquids like petrol, benzene, acetone, etc.

8th Class Physical Science Textbook Page No. 57

Question 14.
Certain fry pans are said to be non-stick. What made them as non-stick?
Answer:
Teflon is special plastic on which oil and water do not stick. It is used for non-stick coating on cookwares.

Question 15.
Firemen wear dress which does not catch fire. What type of fabric it is made of?
Answer:
Melamine is a plastic which is fire resistable and flame resistant is used to make the dress of firemen.

8th Class Physical Science 4th Lesson Synthetic Fibres and Plastics Activities

Activity – 1

Question 1.
Identify household articles made up of natural and synthetic fibres.
Identify the articles around you in your surroundings and write their names against relevant category in the table.
Answer:

Source	Articles
1. Natural fibres from plants	Cotton saree, dresses, curtains, kerchiefs.
2. Natural fibres from animals	Silk clothes, Woolen clothes.
3. Synthetic fibres	Nylon clothes, rayon clothes, polyester clothes, plastic chairs, plastic carry bags, electric switches, plastic bottles, T.V. cabi­nets, etc.

Activity – 2

Question 2.
Beads and paper clips pattern.
Take a few paper clips and join together as shown. Observe the pattern of clips.

a) Do you find any similarity between the pattern of beads in necklace and the pattern of paper clips in the chain.
Answer:
Yes, each unit of paper clips or beads can be joined together to form a long chain structure.

b) What happens if small unit of chemical substance is combined together?
Answer:
It forms a large unit of polymer.

c) How does we obtain synthetic fibres?
Answer:
Synthetic fibres are obtained from polymers.

d) What are the source of synthetic fibres?
Answer:
Petrochemicals.

Activity – 3

Question 3.
Identifying fibres – burning test
You can do a fibre burning test. Unravel several wrap and weft yarns. Using tweezers hold the yarn to the edge of a flame. Observe, the changes.
a) If it smells like burning hair, what is the yam is wool or silk?
Answer:
It is wool or silk.

b) If it smells like burning paper, what is the yam?
Answer:
The yarn may be cotton or rayon.

c) If the yam melts in the flame, what is the yam?
Answer:
The yarn is synthetic fibre such as nylon and acrylic.

Activity – 4

Question 4.
How strong is nylon?

Take an iron stand with a clamp. Take cotton, wool, nylon and silk thread about 50 cm in length. Tie cotton thread to stand so that it hangs freely from it. At the free end, attach a pan so that a weight can be placed on it. Add weight starting from 10 grams one by one till the thread breaks down. Note down the total weight required to break the thread. Repeat the same activity with threads of wool, silk and nylon.

a) Arrange the thread in the order of increasing strength.
Answer:
Cotton < Wool < Silk < Nylon

b) Do you know that if you compare nylon thread with a steel wire of same thickness, nylon will be as strong as steel wire?
Answer:
Yes, it is the strongest man made fibre.

Activity – 5

Question 5.
Why do we combine fibres?
a) Whenever you buy clothes or ready made garments observe the brand label. What do you notice?
Answer:
There is some information about cloth is written on the brand label.

b) What do you see?
Answer:
We can see quality, shade no, width, contents and wash care of the cloth.

c) What is the percentage of fibres?
Answer:
40% polyester and 60% cotton.

d) Why do we combine fibres? What is the process called?
Answer:
We would combine two fabrics to get a fabric which has best qualities of both. This process is called blending.

Activity – 6

Question 6.
How can you say a bottle is PET bottle?
Collect different kinds of water bottles of your classmates and look at them carefully.
a) Do you observe any triangle shaped symbol at the bottom of the bottle or on the brand label of the sticker?
Answer:
Yes.

b) What number is marked at the center of the triangle?
Answer:
I had observed number 5.

c) If code no. is 1 what it indicates?
Answer:
It indicates PET bottle.

Activity – 7

Question 7.
Identification of various articles with recycling codes.
Collect bottles of soft drinks (500 ml or more), bottles of juice and containers of fruit jam, Ketchup, shampoo, coffee powder and try to look for the triangle. You can also go to the near by shop and request the shopkeeper show you the bottle.
a) What are these codes?
Answer:
These are recycling codes of various types of plastic material.

b) What is the use of these codes?
Answer:
We can identify what kind of material is used for the preparation of article by seeing the code at the bottom of the article.

c) Are all bottles found with codes?
Answer:
Yes, all bottles have codes.

d) What code is observed for soft drinks and juices?
Answer:
We can observe code T marked in the middle of triangle.

e) What about Boost or Boumavita bottles?
Answer:
We can observe code 5 marked in the middle of triangle which tells us the bottle is made up of polypropylene.

Activity – 8

Question 8.
Types of plastics.
Let us take two bottles made up of plastic. One is PP bottle and another ordinary (PET) Pour some hot water in both.

What do you notice?
Answer:
The ordinary bottle get deformed.

a) What is the code of the deformed bottle?
Answer:
Code No. 2.

b) What is the name given to plastics which are deformed easily on heating?
Answer:
Thermoplastics.

c) What is the name given to plastics which are molded once can’t be s heating?
Answer:
Thermosetting plastics.

d) Can you tell Topper ware is thermosetting plastic or thermo plastic?
Answer:
Thermosetting plastic.

Lab Activity

Identify whether given plastic material is thermoplastic or thermosetting plastic by using flame test. (OR)
Conduct a flame test to identify thermoplastics and thermosetting plastics. (OR)
You are given a comb, tooth brush handles, plastic bucket, handle of utensil, Electric switch, piece of melamine of meals plate and coffee mug. Explain how can you identify which object is a thermoplastic or thermosetting plastic through an activity.
Answer:
Aim: Identifying thermoplastics and thermosetting plastics by flame test.
Material required: Pair of tongs, spirit lamp, samples of plastics (pieces of comb, tooth brush handle, plastic bucket, handle of utensil, electric switch, piece of melamine of meals plate and coffee mug).
Procedure:

1. Take a spirit lamp and light it.
2. Clamp one piece of plastic sample say piece of tooth brush with tong.
   
3. Place the sample on spirit lamp flame.
4. Observe the changes during the burning of sample.
5. Note your observations like, whether sample is being softened or burnt with smell or become hard, etc.
6. Repeat the procedure with other samples.
7. Record your observations sample wise in the table.
   

   Name of the plastic sample	Softened / burnt with burning smell and become hard	Thermoplastic/ Thermosetting plastic
   Tooth brush handle	Softened	Thermoplastic
   Comb	Softened	Thermoplastic
   Piece of bucket	Softened	Thermoplastic
   Handles of utensil	Burn with burning smell and become hard	Thermosetting plastic
   Electric switch	Burn with burning smell and become hard	Thermosetting plastic
   Meals plate	Softened	Thermoplastic
   Coffee mug	Softened	Thermoplastic

Activity – 9

Question 9.
Biodegradable – Non-biodegradable:
Let’s take peels of fruits and vegetables, left over food stuff, waste paper, cotton cloth and plastic bag. Keep this material in a pit. Open the pit after some days and list the material which remain a long time and those that disappear quickly.

Type of waste	Approximate time to disappear	Change
1. Peels of fruits and vegetables	1 to 2 weeks	degradable
2. Left over food stuff	1 to 2 weeks	degradable
3. Waste paper	10 to 30 days	degradable
4. Cotton cloth	2 to 5 months	degradable
5. Plastic bag	Several years	non-degradable

a) What is the name given to certain material which can be break down into smaller fragments in the presence of water, sun light and oxygen and by bacteria?
Answer:
Biodegradable.

b) What do we call the material which are not decomposed by natural process?
Answer:
Non biodegradable.

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 9 Production and Management of Food From Animals Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 9th Lesson Production and Management of Food From Animals

8th Class Biology 9th Lesson Production and Management of Food From Animals Textbook Questions and Answers

Improve Your Learning

Question 1.
One honey bee hive consists of different types of bees. What are they? How they differ from each other?
Answer:

1. Honey bee species are social insects, which lives in colonies.
2. A honey bee colony consists of three types of bees.
3. One queen, several thousands of workers and few hundreds of drones.
4. There is only one queen bee in a colony. The primary function of a queen is to lay eggs (800 – 1200 eggs per day). The life span of queen is two to three years.
5. A worker has 5-6 weeks and the drone has 57 days of life span.
6. There are sterile female which are called workers in the hive. These bees attend to indoor duties during first three weeks during first three weeks of their lives such as secretion of royal jelly, feeding of the brood.
7. After three weeks they attend outdoor duties like collecting nector, pollen and water.
8. Drones are the male members of the colony. They are very lazy and unable to gather food. Their main duty is participating in mating, after this they die.

Question 2.
Make a list of characters of local variety buffaloes, which gives good quantity of milk in your village.
Answer:

1. Buffaloes are most common in India and other Asian countries.
2. In general, buffaloes give more milk than cows and buffaloes milk has more fat than the cow’s milk.
3. Buffaloes are more resistant to diseases than cows.
4. There are about seven different breeds of buffaloes, Murrah, Bhadwari, Jaffrabadi, Surthi, Mehsana, Nagpri and Nili Ravi in our country.
5. Each breed of buffalo is found in specific regions of the country and they differ in their body colour, shape and length of horns and in the shape and size of their forehead.
6. Of these different breeds of buffaloes, Murrah breed of buffaloes have been recognised by Government of India, as the best native milk yielding breed.
7. It yields about 8 litres of milk/day/animal and about 1800 – 2200 litres per year.

Question 3.
Explain the process of hatching eggs under broody hen in rural areas.
Answer:

1. Hatching of eggs is an interesting process.
2. The common village hen has less care and attention.
3. So it’s productivity is low.
4. It has the capacity to lay 15 to 20 eggs an egg per day respectively.
5. After that the hen becomes a broody state (wish to hatch the egg).
6. In this process the people of the house arrange the eggs in such a way that the broody hen can sit comfortably on the eggs to hatch.
7. The hen sits on the eggs stretching its wings to provide heat to the eggs, to develop chicks inside the eggs.
8. It takes 21 days to the chicks emerges out by breaking the egg shell. This process is called incubation.
9. Almost all the eggs hatch into chicken but some eggs which do not get sufficient heat from the broody hen become rotten.

Question 4.
Write about the accessory products produced in animal husbandry.
Answer:
Milk, meat, eggs, wool are the accessory products of animal husbandry.

Question 5.
What is estuaries, how they are suitable for both marine and river fish to live?
Answer:

1. Estuary is the place where river joins the sea usually called mouth of the river. In this area fresh water (with low salt content from the river) is mixed up with sea water (with high salt content).
2. When the wave action is strong or during high tide, large amount of sea water mixes with river water. In fact sea flows deep into the river.
3. During low tide and when the wave action is weak, less amount of sea water mixes with river water.
4. Because of this, salt content of the water in the estuary changes very rapidly.
5. Animals living in the estuary should tolerate and adopt to rapid changes in the salt content of water.

Question 6.
If you have a chance to visit milk chilling centre, what doubts would you like to clarify? Please list out them.
Answer:

1. Chilling of milk means rapid cooling of raw milk to sufficiently to low temperature. So that the growth of microorganisms present in the milk is checked.
   Doubts to clarify
2. What would happen if the temperature of the milk should be reduced to less than 10°C preferably 3-4°C, in the chilling process?
3. Whether the growth of the microorganisms will be controlled as the required nutrients and the growth conditions will be favourable to them?
4. If the growth of the organisms will not be checked what would happen to the milk. Any changes would happen? Is it fit for consumption?
5. If milk has to be transported to longer distances, considerable time is involved between production and heating process.
6. During this period milk should be protected from spoilage by the action of micro-organisms the chilling process therefore considered is necessary.

Question 7.
Collect news from news papers about milk production and impurities in milk.
Prepare a note and display it on wall magazine.
Answer:
Milk Production:

1. Our government treats producing milk as an industry.
2. Generally farmers rear 1 to 5 cattle in small scale at their homes to produce milk.
3. Among cows, traditional species give 2-5 liters of milk in a day. Murrah species are reared in most of the districts in our state.
4. They give up to 8 liters of milk per day. Haryana, Jaferabad, Nagapuri are the traditional variety of cows which give good quantity of milk.
5. Jersy (England) and Holstein (Denmark) are the foreign varieties. They give 25 liters of milk per day.
6. These foreign varieties are cross breed with our traditional local varieties. They give 8-20 liters milk per day.
7. Cows play vital role in total milk production of our country.
8. Out of milk produced in our country 60% is used to prepare cheese, cova, ghee, curd, milk powder and other milk products.
9. The milk produced in dairy forms is collected from house holds and pasteurized.

Impurities in Milk

1. Addition of pure or impure water.
2. Addition of colouring matter.
3. Addition of preservatives like Sodium bicarbonate, Borax or Boric Acid, Salicylic Acid and formaldehyde.
4. Addition of substances used for thickening after dilution with water, e.g. Flour, arrowroot, chalk, carbonate of magnesium.
5. Sugar is added to raise the specific gravity of diluted skimmed milk.
6. Milk is contaminated by
   a) improper or poisonous food eaten by the animal.
   b) Poor condition of animal due to nursing.
   c) Contamination of disease germs from the cub.
   d) Absorption of bad odours.
   e) If milk has been diluted it becomes pale and blueish, so milk and cream are artificially coloured with anilines or other pigments. Annotto is the common dye used to milk cream and butter.

Question 8.
Collect information about sea weeds, sea kelp from your school library and write a note with examples.
Answer:
Sea Weeds:
Sea weeds constitute an important marine resource and are found along the Rocky intertidal and subtidal regions of the coasts of India. The Sundarbans, the Chilka lake, the deltas of Godavari and Krishna. Gulf of Mannar. Palk bay Gujarath coast and around Lakshadweep, Andaman and Nikobar Islands are areas rich in sea weeds. They are used for human consumption, as cattle and poultry feed, as manure and for industrial purposes as the source phyco colloids like Agar-agar.

Sea Kelps:
Kelps are the largest sea weeds belonging to the brown algae (phaeophyceae) in the order laminariales.
Kelps grow in under water in shallow oceans, it has a high rate of growth and it’s decay is quite efficient in yielding methane as well as sugars that can be converted into ethanol.
It has been proposed that large open ocean, kelp farms could serve as a source as renewable source of energy.
Unlike some biofuels, such as corn, ethanol, Kelp energy avoids “food verses fuel” issues and does not require irrigation.

Question 9.
Observe nearby poultry farm and findout how do they export eggs to market? What material is used for transportation?
Answer:

1. The most important component in the marketing of eggs is to handle them with care at the time of collection, transportation and in the sale counter.
2. To avoid breakage of eggs special designs are planned in the poultry forms. They are packed in tailor made egg trays which can be piled up one over the other after inserting eggs in each tray.
3. These trays protect the eggs from both vertical and horizontal friction and avoid breakage during transportation.
4. The design of the transport vehicles for the chicken are also specially designed cages to allow the requisite freedom to the birds.

Question 10.
Observe a dry honey bee hive and how the bees built it. Draw a picture. How does it look like?
Answer:

Honey Bee hive is a construction of six sided (hexagon) wax compartments made by bees to store honey and eggs.
Wax is produced by the honey bees is known as bee’s wax or honey wax. Wax is used in the production of cosmetics, shoe polish, candles and leather industry.

Question 11.
Agriculture and animal husbandry are both sides of the same coin. How can you justify this?
Answer:

1. Farmers adopt different methods of management for getting better yields in agriculture. In the same way, care is required in the management of reading animals also.
2. Since long ago, man used animals not only for obtaining food but also for agriculture, transportation.
3. People living in rural areas used to domesticate animals like cows, buffaloes, bullocks, goats, sheep, pigs, hens etc., supplying of nutritious food accommodating clear and hygienic, shelters for animals is very important issue in animal husbandry.
4. Generally villages send their cattle to rear in their fields. Where grass is easily avail-able. These animals provide him with food (milk, meat, eggs etc) and clothing. Man in turn protected, fed and took care of these domestic animals.
5. The selective relationship between man and the domestic animals has become in-dispensable – man cannot live without them and these animals cannot survive in wild.
6. Thus, the relationship is mutually dependent and beneficial.

Question 12.
How do you appreciate the uses of cattle?
Answer:

1. Cattle are not only for our food, even its excretions like dung and urine also we make them use. Cow dung is used as a cooking fuel, sanitizing cleanser, construction material, insulation and water proofing for walls and floors in rural houses, a cultural symbol in religious worship, the raw material for producing organic compost and generating electricity.
2. The urine of cows is considered an elixir of life and is used as a natural remedy for liver and heart conditions as well as for enhancing mental and physical strength and increasing longevity.
3. The utilization of cow dung and urine is a perfect example of sustainable living. An understanding of the use of cow dung and urine by the rural Indian population can illustrate the indigenous knowledge associated with these materials and alternative sources of materials for electricity generation as well as cost-effective and environmentally friendly fuel and medicines.
4. Even the ash formed from burning of dung can be used as a cleaning agent for household utensils or used as a fertilizer.
5. Cow manure contains several plant nutrients including nitrogen, potassium, calcium and magnesium. The composition of cow manure makes it ideal for several uses, including fuel, fertilizer and medicine.

Question 13.
What makes you amazing in division of work in Honey bee colony? Support your answer.
Answer:

1. Honey bees lives in colonies. It consists of three types of bees.
2. One queen bee, several thousands of worker bees and few hundreds of drones or male bees.
3. The primary function of a queen bee is to lay 800 – 1200 eggs per day.
4. The worker bees are the sterile female bees. They attend to indoor duties like secretion of royal jelly, feeding of the brood during first three weeks.
   After three weeks they attend outdoor duties like collecting nector, pollen and water.
5. Drones are the male members of the colony. They are lazy. Their main duty is participating in mating. After this they die.
6. Thus the division of work is amazing in honey bee colony.

Question 14.
Conversion of agricultural lands into fish ponds leads to food crisis and environmental pollution. Write your opinion to conduct in debate on this issue.
Answer:

1. Fish culture is not new to our country. Even today in several villages, fishes are grown in small ponds in the backyard of the houses. Besides this, growing of fishes in rice fields is also more common in villages. In fact fish production is considered as second crop for farmers, the primary crop being rice.
2. Fish culture is sometimes practised in combination with a rice crop, so that fish are grown in the water in the paddy field.
3. Growing fish in paddy field is also multi-utilitarian practice. The reason for this are the increasing use of inorganic fertilizers and insecticides in paddy fields which cause deleterious effects on fish and predation for birds, snakes etc.
4. Cultivating fish in paddy fields lower diseases like stem borers on paddy.
5. If the agricultural fields are converted to fish pond, food grains would not be sufficient for the growing population. This leads to food crisis.
6. But ours is a agricultural country. So agriculture will be done in the crop seasons, and in the unseason they can convert to fish pond.
7. The places where it is near to the water sources farmers can utilize these places for growing fish.

8th Class Biology 9th Lesson Production and Management of Food From Animals InText Questions and Answers

Question 1.
What are the food items that are obtained from animals?
Answer:
Milk, meat, eggs, honey.

Question 2.
Do we get our food only from domesticated animals? List out the food that is obtained from animals.
Answer:
We domesticated only such animals which were helpful to us. Buffalo, Cow etc. are reared for milk. Hens, goats, sheep for meat, ducks for eggs.

Question 3.
Do you know the period from which wild animals were being tamed?
Answer:

Name of the Animal	Period of Domestication
Dog	30,000 – 7,000 BC
Sheep	11,000 – 9,000 BC
Pig	9,000 BC
Goat	8,000 BC

Question 4.
Why did early man domesticate only some of the animals?
Answer:
Domestic animals provide him food, (milk, meat, eggs), clothing (skin of the animals). The early man realised the capabilities of these animals, tamed and domesticated them to help him in his daily activities.

Question 5.
Why he did not domesticated animals like elephant, tiger, lion etc. or birds like eagle and owl?
Answer:
They are the wild animals and it is difficult to tame them. There is no use of these animals for his daily activities.

Question 6.
Do all the persons who won agriculture fields also rear cattle?
Answer:
All most all the persons who won agriculture fields, rear cattle also.

Question 7.
Is there any relation between agriculture and cattle rearing or animal husbandry?
Answer:
Cattle provide him food, help in agriculture and transport, man provide food for the animals from the agricultural fields.
Collect the following information from your calls.

Question 8.
Number of families in agriculture
Answer:
Less families

Question 9.
Number of families in agriculture along with animal husbandry.
Answer:
Almost all families.

Question 10.
Number of families in Animal husbandry alone.
Answer:
Less families.

LET US DO Cattle Rearing:

Question 11.
Form a group with four or five students in your class. Discuss about the reasons. Why does a farmers rear cattle?
Answer:
Farmers believe that animal husbandry is part and parcel of agriculture.

Question 12.
Where do people rear their cattle in your village?
Answer:
Generally people send their cattle to rear at the places where grass is easily available.

Question 13.
What are the cattle here?
Answer:
Cows, buffaloes, goats, sheep.

Question 14.
At which places fodder is available?
Answer:
Fodder is available in fields and open places.

Question 15.
What are places where water is available?
Answer:
Canals, ponds, wells etc.

Question 16.
Are there any differences between rearing of cows, buffaloes, goats and sheep?
Answer:
All the animals are herbivorous animals. Farmers use bullocks in agricultural practices like ploughing.

Question 17.
What are the major problems that cattle rearers generally face?
Answer:
Cattle sheds become unclean because of the remains of fodder, dung and urine. Care should be taken to prevent the growth of lice and mytes on cattle’s body.

Question 18.
Make a list of agricultural practices by using bullocks and the buffaloes.
Answer:
Ploughing, to draw the leveller, transporting agricultural goods etc.

Question 19.
Think in which way this practice is helpful to the farmer as well as field crops?
Answer:
Sheep and goats provide him meat and wool, the dung and urine becomes good manure to the field crops.

Question 20.
Where is veterinary hospital located in your area?
Answer:
It is located at the place where it is convenience to the people to bring their animals for check.

Question 21.
Who are working there and what do they do?
Answer:
The employees working in veterinary hospital are a veterinary doctor or animal husbandary assistant, a compounder and attenders. They provide treatment and health care for the cattle.

Question 22.
Meet a nearby veterinary doctor or animal husbandry assistant. Collect infor¬mation about common diseases in cattle and prepare a note on them.
Answer:

1. Gali Kuntu is a common and dangerous disease in cows and buffaloes.
2. Sheep and goats suffer from worm infections (Nattala Vyadhi)
3. Growth of lice and mytes on cattle’s body.
4. Some parasitic diseases cause damage to liver intestine.
5. Viral and bacterial diseases also effect on milk production.

Milk Production:

Question 23.
From which animals we get maximum milk production?
Answer:
Cows, buffalows

Question 24.
In which areas people use camel milk?
Answer:
Desert areas.

Question 25.
Have you ever see people taking donkeys milk? Why was it preffered?
Answer:
Yes. Donkey milk which is Rich in immunoglobulin helps human body from many viral and bacterial infections. These are mostly found in Telangana regions especially in Adilabad. The secret behind the glowing skin of Egyptian princess Cleopatra’s is donkey milk.

Question 26.
What are the types of fodder generally farmers feed the cattle with?
Answer:

1. They supply fodder from their agricultural fields.
2. They also feed the cattle with hay, green and dry grass, oil seed cakes of ground nut.

Question 27.
How farmers preserve fodder for cattle after harvesting?
Answer:
After harvesting farmers preserve fodder by arranging into heaps. This heap will be used for the cattle throughout the year.

Pasteurization :

Question 28.
Is there a milk collecting centre in your village?
Answer:
Krishna Milk Union, Vijaya Dairy Milk centres are located in our village.

Question 29.
How do they collect milk and export?
Answer:
The milk produced in dairy farm is collected from households and cattle rearers and export the milk in chilling form (cooling condition).

Question 30.
Do you know how they decide cost of milk?
Answer:
The cost of milk is decided due to fat content.

Question 31.
Do you know in which month the rate of milk production is high? Why?
Answer:
September to November the milk production is high.

Question 32.
Why the milk production is higher during those months than remaining year ? Discuss with your friends and find out the reasons.
Answer:
Milk production is slightly higher in the November and December months. Because

1. In these months food availability is rich and intaking of good food increase the milk production.
2. the climate is cool and enough hot. This sunny weather increase the milk production.
3. water resources are well in these months. Availability of food and water leads to milk production.
4. mostly animals delivered in July and August months and give milk before the summer. So the availability of milk is higher in November and December months.

Selection Procedure:

Question 33.
What care should be taken while buying cattle for milk production?
Answer:
The following points should be kept in mind.

1. Select high milk producing varieties, either traditional or hybrid.
2. Observe 2 to 3 days for average milk production.
3. Number yielding size, health, eating fodder.
4. Consult veterinary doctor, official of Director of Animal husbandry.

Some of rural people are experts in identifying high producing varieties.

Question 34.
What occasions, They decorate their cattle in your village?
Answer:
Pongal, Onam etc.

Question 35.
Do they respond when called by names ? Do you have any such experience with your pets ?
Answer:
We see the pet dogs climbing our body, sitting beside us, moves it’s tail and licks our feet when we call.

Poultry:

Question 36.
Collect information about Biogas Productions from your school library or internet and write notes on Biogas.
Answer:

1. In recent years, an alternate and better method is used to obtain energy from cattle dung and from the excreta of other animals including man and some types of organic waste material from agriculture, homes and industries.
2. This is by anaerobic fermentation of waste, to produce a gas which can be used as fuel. As this gas is produced from biological wastes, this is called BIO GAS.
3. Biogas is a mixture of gases – methane, carbondioxide and small amounts of hydro-gen, nitrogen and hydrogen sulphide. About 200 cc of biogas gives about 900 K.Cal of energy.
4. Production of biogas occurs in three stages. In the first stage, aerobic bacteria are allowed to degrade the complex molecules into simple molecules.
5. In the second stage, the simple molecules are fermented anaerobically to produce organic acids mostly to acetic acid.
6. In the final stage methane producing bacteria act on the acetic acid under anaerobic condition produce methane. The gases produced are collected into specially constructed chambers and supplied to users.
7. Use of bio gas for domestic purposes (cooking) lighting of street lights etc.
8. When bio gas is burnt, it does not pollute the environment.
9. The left over material after the production of bio gas can be used as manure in agriculture.

Question 37.
Are the hens reared in the poultry is same as our traditional varieties reared by farmers in the village?
Answer:
Farmers rear cocks and hens in villages. Most of these are local varieties (Natukollu). Poultry farms are of two types. One is for production of eggs (layers) and other for meat (Broilers).

Question 38.
Think and discuss Is genetically modified food useful or not?
Answer:
Natural wild varieties grow fully in 5 to 6 years. But broilers grow fully in just 6 to 8 weeks. This happens due to genetic modifications in the hen. So genetically modified food is useful.

Question 39.
Do you know Chicken 65? Why is this called so?
Answer:
This preparation is prepared by A.M. Buhari, in South Indian food industry in Chennai, in the year 1965. So this is called Chicken-65.

Question 40.
Have you heard about cock fight during some festival seasons. Think and discuss in your class about this type of practices which show human cruelty towards animals.
Answer:

At the time of Pongal festival, in some places like India and Tamilnadu, the birds are equipped with either metal spurs or knives tightly tied to the legs in the area where the cock’s natural spur has been partially removed. In this cock fight both the cocks would be wounded, severely bleed, this leads to the death of the birds. By watching this cock fight show, people get enjoyment. This shows human cruelty towards animals.

Question 41.
Do you know how many days a hen spends to hatch it’s eggs?
Answer:
A hen spends 21 days to hatch its eggs.

Question 42.
Prepare a detailed note on hatching eggs by observing at your village. If you need, please draw pictures also.
Answer:

Hatching of eggs into chick is called as incubation period. The full incubation period for an egg is 21 days. During this time the hen sits on her eggs and maintains a temperature of 100°F, which is needed to ensure proper embryonic development.

Question 43.
Egg is a nutritious food. Collect information about various nutrients in egg and write a note on them in your notebook.
Answer:
The nutrients present in egg are is as follows:
Choline: Healthy cell membranes
Vitamin – B: Folate and Riboflavin – converts food we eat into energy. Folate also reduces homocysteine levels and prevent birth defects.
Vitamin – A: Vision and healthy skin.
Vitamin – E and Vitamin – C also present
Luteine and Zeaxanthin: Found in yellow pigment of yolk, prevent macular degeneration.
NECC:
If you want to be healthy person eat egg everyday. This is the slogan of National Egg Co-ordination Committee. Egg is chief nutritious food which is easily available for all.

APICULTURE:

Question 44.
In what way honey bees are helpful in pollination?
Answer:
Honey bees are helpful in pollination, there after growth of food grains.

Question 45.
Generally where do you find honey bee hives in your surroundings?
Answer:
Those plants which contain nectar and pollen liked by bees are called bee flora. We find honey bee hives on the fruit trees like citrus, apple, guava, tamarind, cultivated field crops like mustered, gingelly, wheat, cotton, sunflower, vegetable plants like beans, bendi, brinjal, Trees like acacia, neem, sal and bushes, shrubs.

Question 46.
In which seasons we find honey bee hives?
Answer:
In winter and summer seasons we find honey bee hives.

Question 47.
Collection of honey from hive is a careful activity. Write a note on how people collect honey from hives. What did they do for this ?
Answer:

1. People take risk to collect honey from hives.
2. They burn some plants or wood to make smoke. They cover their body with a thick blanket.
3. They put the smoking material into a container. They take it over to the hive.
4. Working slowly and carefully, they wait for the honey bees to leave the bee hive.
5. Carefully they cut the hive with a sharp knife.
   By pressing the hive they can collect honey.

Question 48.
Ask your parents/teacher how a bear hunts bee hives for honey?
Answer:

1. Before going for hibernation (winter sleep) the bear builts fat reserves in its body and prepares itself for the winter season.
2. The bear attracted towards the bee hive and honey.
3. When it finds bee hive it drives away the bees with its forelimbs.
4. It has the advantage that its body has thick fur and avoids bee sting.
5. It chews the bee hive along with some bees in the hive swallow honeys spits out the waste.
6. This is how a bear hunts bee hives for honey.

FISHERIES:

Question 49.
Write a list of fishes that are available in your surroundings. Just write local names only.
Answer:
Marrel (Korramenu), Katla (Jella), Katrana (Bochu), Rahu (Mosu), Seer (Vanjiram) are the local varieties.

Question 50.
Do you know how to catch fish in a pond?
Answer:
Fishing rod will be helpful to catch fish.

Question 51.
How to catch fish in a large scale?
Answer:
Nylan nets will be useful to catch fish in large scale.

Question 52.
Think what will happen if mechanized fishing continuous for a long run.
Answer:
If mechanized fishing continuous at last we find no fish (extinction)

Question 53.
Ask your teacher what are the uses of Oysters?
Answer:
Oysters are the marine molluscs which produce pears. Economically pearls are important.

Question 54.
Tuna is an important fish which is available in our marine area. Collect information about Tuna and in what way it is important?
(OR)
Poultry Emu culture /Fish forms / Apiculture. Visit any one of the above industries. Get the information from farmers and prepare a note on this.
Answer:

1. Poultry are domesticated birds kept by human for the eggs and meat.
2. Generally chickens, ducks, geese, turkeys, quail are cultivated in poultry.
3. Chicken poultry’s are very common in our areas.
4. Here two types of hen’s are cultivated. Layer’s for eggs, and broiler’s for meat.
5. Poultry’s are arranged in stair manner, which save the lot of place.
6. Modern feeds for poultry consists such as soyabean oil, mineral supplements and vitamins.
7. Daily they collect the eggs and parcel in egg cases to supply.
8. Broiler chickens are domesticated and specially meant for meat production.
9. Poultry become a major economic source in rural areas.
10. It provides work and earning for rural people.

Question 55.
What is blue revolution? What are its effects? Discuss in your classroom.
Answer:
In the recent times, the Department of Agriculture and Cooperation (Blue Revolution) in the country. These schemes include the development of fresh water aquaculture through Fish Farmers Development Agencies (FFDAs) with development of brackish water aquaculture through Brackish Water Fish Farmer’s Development Agencies (BFDAs’ A shrimp and fish culture project is being implemented with World Bank assistance for the development of Shrimp culture in the states of Andhra Pradesh, Odisa and West Bengal.

8th Class Biology 9th Lesson Production and Management of Food From Animals Activities

Activity – 1

Question 1.
Form a group of 5 or 6 students. Collect different types hens and find their characters. If you want to know more details, about you need to ask hen rearers or poultry farmers in your village. Do not forget to collect information about the feed and diseases, treatment by using local technology.
Answer:

1. Production and rearing of hens on a large scale is generally called poultry. So billion hens are reared world wide for eggs and chicken.
2. Farmers rear cocks and hens in villages. Most of these are local varieties (Natukollu). Natural country varieties are good for hatching purpose, Aseel, Kadaknath, Chittagang, Longshan, Bursa are the pure local varieties.
3. Aseel (Berisa Kodi) the Indian traditional variety is meant for fighting because of its pugnacity, high stamina and majestic gait.
4. Feeding: The balanced feed must have nutrients, proteins, carbohydrates, fats, minerals, vitamins and water in sufficient quantities. Minerals like calcium, phosphorus, iodized salt, manganese and zinc are useful for better yield of eggs and meat.
5. Diseases: Poultry chicken are known to suffer from bacterial, fungal and viral diseases. Fowl cholera, salmonellasis and coryza are the common bacterial diseases. Fowl pox and Rani kher are the dreaded viral diseases.
   Fowl mite, chicken mite, fleas, licks, lice etc., are known to be present on the external surface of the poultry chicken and cause diseases and are therefore called as external parasites.
   Round worm, tape worm and coccidiosis are categorized as internal parasites.
6. Prevention and control: Prevention is always better than cure. For most of the diseases vaccines are now available. Newly born chicken should be vaccinated. A wide range of antibiotics, particularly broad spectrum sulfa drugs are widely used for treatment for poultry diseases. When a bird is identified to be suffering from a disease, it should be immediately to be isolated.

AP State Syllabus AP Board 8th Class Physical Science Solutions Chapter 6 Sound Textbook Questions and Answers.

AP State Syllabus 8th Class Physical Science Solutions 6th Lesson Sound

8th Class Physical Science 6th Lesson Sound Textbook Questions and Answers

Improve Your Learning

Question 1.
Fill in the blanks with suitable words.
a) The to and fro motion of a body from its mean position is called ……… .
b) Number of vibrations per second is called ………. .
c) The intensity of sound can be measured in ……… .
d) Sound cannot travel in ………. .
e) Vibrating bodies produce ………. .
f) The maximum displacement of a body from its mean position is called ……… .
Answer:
a) vibration
b) frequency
c) Decibel
d) vacuum
e) sound
f) amplitude

Question 2.
A normal human being can listen to sounds with frequency from …….. to ……. vibrations per sec.
Answer:
20, 20000

Question 3.
How will you differentiate the amplitude and frequency of different sounds? Give two suitable examples from your daily life.
Answer:
The pitch of a sound depends upon sound whereas intensity of sound depends upon amplitude.
If we are hearing a loud sound that means it has greater amplitude.
If we are hearing a feeble sound that means it has least amplitude.
If the shrillness of sound is less then the frequency of the sound is less.
If the shrillness of sound is more then the frequency of the sound is more.
Examples for daily life:
Frequency:

1. The shrillness of adult women is more than adult men because of greater frequency associated with vocal cords.
2. The different sounds produced by whistle and drum are due to difference in frequencies.
3. Amplitude:
   1. The difference in sound produced by lawnmower and car horn due to difference in their amplitude.
   2. The sound produced by crackers during Diwali is due to greater amplitude.

Question 4.
Write any three musical instruments that you know and explain how they produce sound? (OR)
Write any four musical instruments known to you and explain how do they produce sound.
Answer:
The three musical instruments are:

1. Veena: This instrument contain strings of different thickness fixed on hollow wooden boards, with different tensions. When a string of certain thickness fixed under certain tension is vibrated which changing vibrating lengths different sounds are produced.
2. Mridangam: It is in cylindrical shape and it containing membranes fixed with different tensions on the two sides. When it is vibrated by hand or by sticks at different places produce different sounds.
3. Flute: It has a cylindrical tube open at both ends. It is provided with holes in a row on its surface. By blowing air through it, while changing the length of air column, different sounds are produced.

Question 5.
The sounds of crickets (insects) make us close our ears. Why?
Answer:
The sounds of crickets are shrill creaking which make us to close our ears.

Question 6.
Robert observed a musical instrument producing sound. But he didn’t find any vibration of any part of that instrument. This observation raised many questions in his mind. Can you guess what are the questions raised in his mind? Write them.
(OR)
Latha observed a musical instrument producing sound. But she did not find any vibration of any part of that instrument. This observation raised many questions in her mind. Guess the questions raised in her mind and write any two of them.
Answer:

1. How does the instrument produce sound?
2. Whether an object produce sound without any vibration?
3. If it is producing vibration why do we unable to felt it?
4. Does sound has energy?

Question 7.
“Vibrations in a body produce sounds”. How do you prove it?
Answer:
Put a hack-saw blade in between a table and brick as shown in figure and press it and leave it abruptly. It produces sound and we observe hack-saw blade is vibrating. Which proves a vibrating body produces sound.

Question 8.
Can parrots speak? Discuss with your Mends and collect information.
Answer:
Yes, parrots can speak. But parrot do not have vocal cords, so sound is accomplished by expelling air across the mouth of the bifurcated trachea. Different sounds are produced by changing the depth and shape of trachea. So talking or speaking of parrots are really whistling in different variation. Parrots speak without understanding words.

Question 9.
Collect the photographs of local musicians and exhibit them in your class.
Answer:

Question 10.
Collect photographs showing various situations of sound pollution and prepare a scrap book.
Answer:

Question 11.
Zakir said “vibrations produce sound. And sound produces vibrations. This is how we hear every sound”. Establish that the given statement is true with relevant examples from your surroundings.
Answer:
Examples for vibrations produce sound :

1. Fix a rubber band tightly on an empty match box. Pluck the rubber band and keeping it near to our ear we can hear sound that shows vibrating object produce sound.
2. A vibrating hack-saw blade placed between a table and brick produces sound. Which is also an example for vibrating body produces sound.

Examples for sound produces vibration:

1. Sound produced by supersonic planes vibrates the wall of buildings and glass windows due to which we can observe the cracks on the walls or breakage of windows.
2. Take a cell phone and playing music with high volume in a plastic bottle. Close the mouth of bottle with a balloon using rubber band and place sugar crystals above the bottle. We can observe the vibrations of sugar crystals.

Question 12.
Make different musical instruments using local available materials and exhibit them in your class.
Answer:

1. Jalatarang: Take 4 to 5 metal or glass bowls or tumblers. Fill them with water in increasing order. Strike gently each bowl or tumbler with a spoon. We can produce different musical sounds. So it acts as Jalatarang.
2. Two note flute: Get a jug or bottle. Cut a smaller than finger sized hole in the bottom of the bottle / jug. Blow across the hole that is already in the top of the jug/ bottle until you get a clear note. Cover and uncover the hole on the bottom with your finger. You can also try tilting your head down and up to make the note sharp or flat.
3. Drum: Get a plastic paint barrel. Put it on the ground between your feet or in the crook of your elbow. Play it like a drum.
4. Guitar: Take empty shoe box and cut a circle in the middle. Cut six rubber bands so that they can be stretched out to their full length. Press brass fastners into the shoe box placing six on the top and six on the bottom of the box. Stretch out the rubber band, one at time, tying them onto the fastners. Cut a paper roll in half and slide in underneath the rubber bands below the hole. Which will act as guitar.

Question 13.
Explain why we are not able to hear the explosions taking place in the sun.
Answer:
Sound wave cannot travel in vacuum (meaning space). In order to hear sound waves it must required medium. So we are not able to hear explosions happening in the sun.

Question 14.
Write any two slogans to reduce sound pollution.
Answer:
Slogans to reduce sound pollution:

1. The more you make noise. The faster you lose your voice.
2. Noise an evil. You help doing it, it gives you a reward making you a deaf.

Question 15.
Write your suggestions about reducing sound pollution.
Answer:

1. Attach silencers to bikes and other machines to reduce sounds.
2. Manufacture machines that work with less noise.
3. During the use of TV and taperecorder tune down volume of sound.
4. Plant trees to reduce sound pollution.
5. Community laws must. Silence zones near school/colleges, hospitals, etc.
6. Noise producing industries, airports, bus and transport terminals and railway stations to sighted far from living places.

Question 16.
How does sound pollution effects bio – diversity? Explain.
Answer:
Slogans to reduce sound pollution:

1. The more you make noise. The faster you lose your voice.
2. Noise an evil. You help doing it, it gives you a reward making you a deaf.

Effects of sound pollution on bio-diversity:

1. The first harmful effect is loss of hearing.
2. It also leads to several health related problems, e.g: Sleeplessness, hypertension, increase in blood pressure, etc.
3. It effects the mental health of people.
4. In animals, noise can increase the risk of death by altering predator or prey detection and avoidance, interfere with reproduction and navigation and contribute to permanent hearing loss.
5. Noise pollution causes poor quality of crops.
6. Under water animals such as whales and dolphins too experience discomfort due to noise pollution caused by submarines, shipping companies and sonars. Cuttle fish and octopus suffer serious damage from noise pollution.

8th Class Physical Science 6th Lesson Sound InText Questions and Answers

Think and Discuss

8th Class Physical Science Textbook Page No. 86

Question 1.
What is the effect of humidity on quality of sound propagation? Is there any difference in propagation of sound in air during the summer and winter seasons? Discuss with your Mends.
Answer:
With increase in humidity, density of air decreases. So with rise in humidity velocity of sound increases.
This is why sound travels in humid air (rainy season or winter) than in dry air (summer) at the same temperature.

8th Class Physical Science Textbook Page No. 87

Question 2.
“Vibrations produce sound and sound produces vibrations”. Which is true in this? Discuss.
Answer:
Yes, it is true. We already know a vibrating object produce sound. Sound is a mechanical wave that can produce vibration. (Mechanical waves have ability to vibrate an object)

Question 3.
“Our ear has the three media through which sound propagates.” Discuss with your Mends as to whether the above statement is true.
Answer:
Yes, it propagates through three media. The first media is external ear, the second media is middle ear, the last media is inner ear.

8th Class Physical Science 6th Lesson Sound Activities

Activity – 1

Question 1.
Listening to sound and predicting its source:
Let us sit quietly for a while and listen to sounds of objects, animals. Prepare a list of sounds that we hear and the sources from which they might have originated. Write them in the table.
Answer:

Sound heard	Source of sound
Feeble barking	Dog from some distance
Bell ringing	School bell
Music	Radio / TV
Noise	Students in a classroom
Horn	Bike / car
Whistle	A student has produced sound from his / her mouth

Activity – 2

Question 2.
Identifying different sounds:
Make a student to stand at the blackboard such that his face is turned towards the blackboard and ask other student in the class to make different sounds. The student at the board should tabulate the sounds he heard and sources of those sounds as shown in the table.

Sound heard	Way of producing sound
Gala Gala	A few stones rattling in a metal box
Eela (whistling sound)	A student has produced the sound from her/his mouth
Tapa Tapa	Someone one striking the table tab with a scale
Taka Taka	Someone thumping the ground with shoes
DabaDaba	Someone knocking at the door
Paka Paka	Someone is laughing

a) How does the student at the blackboard guess the source of sound without actually seeing the source?
Answer:
Student has identified the variations in sound by listening.

b) How do objects produce sound?
Answer:
When we vibrating the objects, they produce sound.

c) What happens when objects made of metals are hit by a hammer or fall down from a height on a concrete floor ?
Answer:
When objects made of metals are hit by hammer from a height, they produce sound.

d) How does a flute or a whistle produce sound?
Answer:
Vibration of air column produce sound in flute or whistle.

e) How would you feel if you touch a body while it is producing sound?
Answer:
My body is vibrating when I touch a body (or object) while it is producing sound.

Activity – 3

Question 3.
Vibrating body produces sound:
Take a brass bell (bell used in Pooja room or in your school).
Ring the bell and listen to the sound carefully. Now hold the bell tightly with your hand as shown in figure and ring it again.

a) Do you hear sound from the bell ?
Answer:
Yes, but slightly.

b) Is there any change in the sound produced in the two situations?
Answer:
Yes, in the second case the sound is feeble.

c) What do your hands feel when bell is ringing?
Answer:
The hand vibrates.

d) Remove your hand and ring it again. Do you hear a different sound? Why?
Answer:
Due to the vibrations are transmitted to hand and bell is not properly vibrating so it produces a feeble sound. Once the hand is removed bell rings properly and sound become louder and different.
Let us do following activities:

e) Fix a rubber band tightly on an empty matchbox. Pluck the rubber band and keep it close to your ear. Do you hear any sound? Do you feel any vibration in your hands?
Answer:
Yes, I heard a sound. I felt the vibration.

f) Blow air into papers of your notebook. What happens? Does the action produce any sound? Do you find any vibrations in the note book?
(OR)
If you blow air into papers of your notebook, sound will be produced. Write your observation in this activity.
Answer:
Yes, it produce sound and I found vibrations in the notebook.

g) Fill a plate with water and let the water settle. Strike the rim of the plate with a spoon as shown in figure. What do you observe? What do you hear? Where do you find vibrations in this case?

Answer:
I heard a sound. The vibrations are found in plate as well as in water.

h) Put a hack-saw blade in between a table and a brick as shown in the figure and press it and leave it abruptly. What happens? Does it produce sound? What is the state of the hacksaw blade while it is producing sound?

Answer:
Yes, it produces sound. The blade is vibrating.

i) What have you observed while doing the above activities?
Answer:
All of them produced sound.

j) What changes took place in those objects?
Answer:
These objects are vibrate while producing sound.
But there are certain instruments which producing sound though we cannot see any vibrations in the instruments like in flute and clarinet etc.

k) How do they produce sound?
Answer:
They are producing sound due to vibration of air column.

l) Is it possible to produces sound without vibration?
Answer:
No, it is not possible to produce sound without vibration.

m) Does every vibrating body produce sound?
Answer:
Yes, every vibrating body produce sound.

n) Does sound has energy?
Answer:
Yes, sound has energy.

Activity – 4

Question 4.
Sound has energy: (OR)
Suggest an activity to prove “sound has energy”.
Take a plastic bottle and a cell phone. Cut the top of the bottle so that it looks like a glass. Play songs on the mobile phone in high volume and place it in the bottle. Close the mouth of bottle with a balloon using rubber band so that it covers the bottle as shown in the figure and stretch it tightly so as to behave like a diaphragm. Place some sugar crystals or small size of sand particles on the balloon diaphragm and observe the movement of particles. Do the same activity after removing the phone from the bottle.

a) What do you notice?
Answer:
When there is no cell phone inside the bottle, sand particles on diaphragm remain stationary. While the cell phone playing songs inside the bottle, the diaphragm vibrates which can be seen through dancing of sand particles. The sound produced by cell phone inside the bottle is responsible for these vibrations. Thus sound has energy to make sand particles vibrate on the diaphragm.
Musical instruments:
You might have observed many musical instruments like Tabala, Flute, Harmonium and Guitar. The sounds produced by these instruments are distinct. It is easy for us to identify which sound is coming from which instrument.

b) How do they produce sound?
Answer:
They produce sound due to vibration.

c) Why there is a difference between the sounds produced by various musical instruments?
Answer:
The mode of vibration is different.

d) Which part of these instruments is responsible for production of sound?
Answer:
Different parts for different instruments:

Name of instrument	Vibrating part of it
Tabala	Membrane, air inside hollow body
Veena	String fixed on hollow wooden board
Flute	Air columns
Clarinet	Air columns
Guitar	String fixed on hollow wooden board
Mridangam	Membrane, air inside hollow body

e) Can you name the instrument for which more than one part is responsible for the production of sound?
Answer:
Tabala, Mridangam.

f) How do you compare the production of sound in a flute and sound produced in a water tap when it is turned on, just before the water flows out of it.
Answer:
Both are same process. They produce sounds due to vibrating air columns.

Activity – 5

Question 5.
Producing a sound that resembles sound of rainfall:
Start clapping with fore finger on left hand palm, add the middle finger and clap again, then ring finger and lastly small finger successively and reverse the process gradually. If all the students in your class do it simultaneously the sounds produced would resemble the on set and stopping of rainfall.

Activity – 6

Question 6.
Observing the changes in sound:
Take 4 or 5 metal glass bowls or tumblers. Fill them with water in decreasing order. Strike gently each bowl or tumbler with a spoon.

a) What do you hear?
Answer:
We can hear a musical sound. This is a jalatarang.
Fill the bowls or tumblers with equal amounts of water, strike each ball like in above case and listen the sound.

b) What difference do you notice in the sound produced?
Answer:
It does not produce musical note in this case.

c) Why is there variation in the sound produced due to change in the water level of a bowl?
Answer:
The change is due to change in air columns. That is sounds are produced by the vibrating bodies and air passes through orifices of the instrument.

Activity – 7

Question 7.
Observing the movements of vocal cords during speech :
Ask a friend to raise his neck up. Stretch a chocolate wrapper across his mouth and ask him to blow air on the wrapper forcibly. Observe the changes in movement at his throat. Ask him to blow again slowly and observe the difference in movements.
a) What changes do you observe in the movements at the throat on the two occasions?
Answer:
During the first trial the voice box gets tensed and produces high sound while during the second trial it is close to normal position of throat and produces lower sound. The sound produced in the above activity is due to a combination of vibrations produced in the wrapper and the vocal cord.
Propagation of sound:
Sound needs a medium to propagate:
The sound produced by the school bell will be heard by all of us irrespective of whether we are in a room opposite to the bell or in a room at the back of the bell. Obviously, the sound produced by the school bell travels in all directions and reaches us, propagating through the air present between source of the sound and our ears. That is the air surrounding us act as a medium which allows the sound to pass through it.

b) Does sound travel only in air?
Answer:
No, it will travel in other media.

c) Does it travel in any other gaseous medium?
Answer:
Yes, it will travel in any other gaseous medium.

d) Does sound also travel in other media like solids and liquids?
Answer:
Yes, it will travel.

Activity – 8

Question 8.
Observing sound propagation in solids:
Strike one end of the table with a pen and ask your friend to listen to the sound produced keeping her ear touching the table at other end and also ask her to listen to the sound by lifting her head slightly from the table. Ask your friend what difference she noticed while hearing the sounds when her ears were away from the table and touching the table.

Take a metal or wooden strip. Strike it at one end and ask your friend to hear the sound by keeping his ears at the other end of the strip. Ask your friend what difference he noticed while hearing the sounds when his ears are away from the strip and touching the strip.

a) Do you know how to make a toy telephone using tea cups?
Answer:
Take two paper-cups. Make small holes at the bottom of these cups. The holes should be very small so that only a thin string can pass through them. Take a long string. Make sure that the string does not have any knots in it. Push the string through the hole in one of the cups. Fix the string by putting a knot at the end. Similarly fix the string to the other cup. Our phone is ready.

You and your friend can communicate with this phone now. Stand away from each other so that the string is tightly held. One of you can speak in the cup while the other can listen by putting the cup on his ear.

b) Are you able to hear the sound?
Answer:
Yes, we can hear the sound.

c) What is a medium between you and your Mend which is responsible for propagation of sound?
Answer:
The medium is thread.
In the above activities you observed that sound travels in solid medium like wood, metal, thread, etc.

Activity – 9

Question 9.
Propagation of sound through liquids:
Take a bucket fill it with water. Take two stones and strike them against each other keeping your hands inside the water. Ask your friend to listen to the sound by keeping his / her ears touching walls of the bucket.

Ask your friend about the difference between sounds produced by striking the stones against each other in water and striking them in air.
Thus the conclusion is that sound propagates through matter in all the three states – solid, liquid and gas.
a) Does sound travel in liquids?
Answer:
Yes, sound can travel in liquids.

b) Can we hear the sound produced in water?
Answer:
Yes, we can hear.

Activity – 10

Question 10.
Does the sound travel if there is no medium?
Take a water tumbler or a glass made of plastic or glass. Make sure that the tumbler or the glass is dry. It should be long enough to accommodate a cell phone vertically. Place a cell phone small in size in the glass and play the ring tone of the mobile. Listen to the ringtone and its volume level. Cover the glass with a small plate and again listen to the ringtone and note the difference in volume of the sound.

Now suck the air from the glass keeping it close to your mouth. If you suck air quickly the rim of the glass will stick around your mouth due to air lock. Listen to the volume of the ringtone at this stage. And also ask your friend to listen to the sound for comparing variation in its volume.
a) Is there any change in the volume of sound observed by you or your Mend?
Answer:
When the tumbler is covered with a plate, the volume reduces but you can hear the ringtone. As we start sucking more and more we can notice that the volume decreases gradually. If the air is sucked completely, you will not hear the sound at all. But practically it is not so easy.
This activity gives an idea about need of a medium for propagation of sound.

Lab Activity – 1

Question 11.
Conduct an experiment to know the relationship between the intensity of sound produced by a body and the vibration of the body.
Answer:
Aim: To know the relation between the intensity of sound produced by a body and the vibrations of the body.
Materials required: Wooden table, 30 cm metal scale or nearly 30 cm hack-saw blade and a brick.
Procedure:
Place the blade/scale on the table, with 10cm of the blade on the surface of the table and rest of it in air. Keep a heavy brick on one end of the 10 cm blade/ scale kept on table.

Vibrate the blade gently and observe the vibrations and simultaneously listen to the sounds. Repeat the same 2-3 times and record observations in the table shown below.
Vibrate the blade using greater force. Observe the vibrations and listen to the sound. Repeat this for 2-3 times and record your observations in the table shown below.

Force	Vibrations of the. blade / scale	Intensity of sound
Small	50	Less
Large	50	More

a) When do you hear a loud sound?
Answer:
When we applied large force we heard a loud sound.

b) When do you hear a feeble sound?
Answer:
When we applied less force we heard a feeble sound.

c) What difference do you notice in vibrations of blade / scale during loud and feeble sounds?
Answer:
During loud sound the amplitude of vibration is more and for feeble sound the amplitude is less.

d) What difference do you find in amplitude of vibration for a feeble and a loud sound in the above experiment?
Answer:
For a loud sound the amplitude is more and for a feeble sound the amplitude is less.

Lab Activity – 2

Question 12.
Explain identification of pitch or shrillness of sound with the help of an activity.
(OR)
What are the characteristics of sound? Explain the procedure to identity the pitch of sound.
Answer:
Chardcteristics sound are 1) Loudness 2) Pitch 3) Quality.
Aim: Identifying pitch or shrillness of a sound.
Materials required: A wooden table, two hack-saw blades or metal scales of 30cm length and a brick.
Procedure:
Place the first blade/scale on the table, with 10cm portion of the blade on the table and rest of it in air. Keep a brick as weight on the 10 cm portion of the blade/scale kept on the table. Vibrations of hack-saw blades
Place the second blade/scale on the table (see that the gap between these two blades is 10cm), with 25cm on the table and 5cm in air. Keep a brick as weight on the scale/blade.

Vibrate both blades with same force. Observe the vibrations and listen to the sounds produced.
Repeat the same 2-3 times and record observations in the table showed below.

Blade length in air	Vibrations	Sound
Blade 1 : 20cm	50	Less shrillness
Blade 2 : 5cm	90	More shrillness

a) What difference do you notice in number of vibrations of two blades?
Answer: The number of vibrations in 5 cm blade is more.

b) What difference do you notice in the quality of sound produced by them?
Answer:
The sound produced by 5 cm blade is more shrill when compared to that of 20 cm blade.

 

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 8 Production and Management of Food From Plants Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 8th Lesson Production and Management of Food From Plants

8th Class Biology 8th Lesson Production and Management of Food From Plants Textbook Questions and Answers

Improve Your Learning

Question 1.
State reasons why wheat is cultivated in Kharif.
Answer:

1. The crops grown in the rainy season are termed as Kharif in the months of June to October.
2. If we cultivate wheat crop in the month of July it takes 8 – 10 weeks for growing.
3. After that flowering will take place. By that time, it would be October.
4. Then the night duration extends more than 12\(\frac{1}{2}\) hours. Wheat plants flowering takes place only in long night durations.
5. Crop production is based on the flowering of plant. If flowering of plant is more, the crop production also is more.
6. Wheat is important cereal crop gained a lot through Green Revolution by developing high yielding hybrid strains.

Question 2.
Ramaiah’s field is flattened. Somaiah’s field has many up and downs. Who will get more crop ?
Answer:

1. Generally the fields have a lot of ups and downs even after ploughing. So a leveller is used for levelling the soil.
2. By levelling the soil, it becomes flattened, water and nutrients can be reached to every part of the land. It also helps in sowing seeds and planting.
3. Because Ramaiah’s field is flattened, he will get more produce than Somaiah.

Question 3.
What are the advantages of ploughing?
Answer:
Before growing crops ploughing the soil properly is necessary.
Advantages:

1. Ploughing loosens the soil and it helps in easier transportation of air and water.
2. Water is stored deeply for a long time as the soil is soft.
3. Roots penetrate in the deep and can respire well as the air enters easily into the soil.
4. Friendly microorganisms and earthworms can grow well when the soil is soft.
5. Some foe microorganisms die due to the sun rays.

Question 4.
Treating with fungicides before sowing the seed is necessary. Why?
Answer:

1. Sometimes farmers wash seeds with chemicals to protect from pests.
2. Medication is done to keep away the seeds from the harmful microorganisms like bacteria, fungi etc.
3. So, generally farmers treat the seeds with fungicides before sowing the seeds before making them to germinate.

Question 5.
Why do farmers dry the paddy crop after cutting them from fields?
Answer:

1. Naturally food produce can be damaged by fungi, pests, rats and bacteria.
2. If moisture is also there in the grains, it helps to develop moulds (fungi).
3. Such grains neither germinates nor suitable to eat.
4. To overcome this problem farmers dry the grains for 2-3 days in sun.
5. After drying they keep the grains in jute bags and preserve them in godowns.

Question 6.
Give some examples of plants that grow after replanting.
Answer:
Seeds that are broadcast in a plot, grow into seedlings. When these plants grow to certain height, farmers pick out the plants (seedlings) from the plots, make bundles and are sown in proper distances. This is called transplantation (replanted)
E.g.: Rice (Sri Vari), Tobacco, Onions, Chillies etc.

Question 7.
Rahim removed weeds in his crop field, but David did not. Guess who get more yield. Why?
Answer:

1. Rahim get more yield than David. Because
2. Weeds are the unwanted or undesirable plants which grow in the fields and compete with crop plants for water, nutrients, light and space.
3. Because of these plants the crop plants may not grow properly. So they should be removed.
4. Otherwise the yield of the crop will be reduced.
5. Weeds give shelter for insects, pests and microorganisms and serve as a host for them.
6. Weeds are capable of germinating and growing fastern than crop plants. They flower and form seeds much earlier than the crop plants.
7. Some weeds disperse pollen grain to air which in turn causes respiratory diseases.

Question 8.
What is natural manure? How to prepare it? Give two examples.
Answer:
Natural manure: A manure made by the decomposition of plants and animal (organic) wastes is called natural manure or natural fertilizer or Bio Fertilizer.
Preparation:

1. These fertilizers are formed by decomposing plant and animal wastes.
2. In rural areas farmers keep these plant and animal wastes outside the village in open space.
3. Some bacteria like Azatobacter, Nitrobacter decompose and it becomes manure which contain nutrients.
4. Wherever the manure is added to the soil, there it provides nutrients to the plants. Examples : Vermi compost, Dung fertilizer.

Question 9.
Why do farmers plough their field during summer?
Answer:

1. Ploughing loosens the soil and it helps in easier transportation of air and water.
2. In summer temperature is very high. So the soil becomes dry. Then the soil becomes very loosly.
3. Some foe microorganisms die due to the sunrays.

Question 10.
Rajendar cultivated cotton crop in his field. He did not get sufficient yield. Can you guess the reasons? (OR)
A farmer cultivated cotton crop in his field. He did not get sufficient yield. Guess any four causes for it.
Answer:

1. Farmers in our state generally purchase seeds in the nearby market. The grains that are available in the packets play vital role in agriculture.
2. Sometimes the rate of germination of the seeds is not up to the mark, which was labelled on the packet.
3. Sometimes never germinate too.
4. At times, seeds grow into plants but they be sterile.
5. And sometimes the crop may be attacked by the larva of spotted brown boll-worm and pinkish boll-worms.
6. The larva of brown catter pillar sucks the juice from the leaves. The buds and the fruits of cotton plants drop off from the infected plants.
7. The larva of pinkish boll worm of cotton make hole in the stem, flower buds, flowers and fruits. As a result flower buds, cotton bolls drop off.
8. May be these reasons Rajendar did not get sufficient yield.

Question 11.
I am a plant. I grow in crop fields. Farmers pluck me. I do not know the reason. Can you tell who am I ?
Answer:

1. We observe some other plants growing along with the crop plants These are undesirable plants called weeds. They should be removed immediately.
2. The weeds, compete with the crop plants for nutrients, water and light, so he crop plants may not grow properly. This is the reason why they (weeds) should be removed.
3. Besides competition for food, light and water they also work as a carrier for different diseases. They also serve as host for different pests.
4. Some weeds disperse pollen grains to air which in turn causes respiratory diseases.
5. So the farmers pluck the weeds from crop plants by using different methods.

Question 12.
What do you observe in the experiment of dropping a fist of Bengal gram seeds in water?
a) What are the differences you observed in both the seeds?
Answer:
We can observe some seeds floated on water, the remaining sank under the water. The seeds which are floated are wrinkled and rough shaped but the sank seeds are round and smooth.
The floated seeds are light in weight but the sank seeds are more in weight.

b) Do you know why the floated seeds are lighter in weight?
Answer:
The floated seeds are not healthy, so they are lighter in weight.

c) Which seeds germinate well? Why?
Answer:
The seeds which sank in water germinate well because they are healthy.

d) Which seeds would not germinate properly? Why?
Answer:
The seeds which are wrinkled and rough would not germinate properly. Because the cotyledon inside the seed would not develop healthy.

Question 13.
Go to your nearest fertilizer shop and collect the information about chemical fertilizers and fill the table. Copy the following table in your notebook.
Answer:

Question 14.
Prepare a flow chart from ploughing to yielding in paddy.
Answer:

Question 15.
How do you appreciate the irrigation systems used in the drought prone areas?
Answer:

1. This method is employed when the availability of water is poor.
2. As the water reaches the plants drop by drop this is called Drip irrigation.
3. A long tube followed by small tubes attached to a motor. The tubes are made holes. So the water comes out from the tube.
4. The holes are arranged in such a way that it provide water exactly at the place where plant roots could receive water.
5. The man’s best technical method of utilizing the water in farming where the conditions are pravailing and in the areas where the availability of water is scanty.

Question 16.
Narendra sprayed over dose of pesticides on his cotton crop. Ramesh says it is a hazard to biodiversity and crop yield. Can you support Ramesh? How?
Answer:

1. In agriculture pests damage the crops. Almost all crops are generally effected by pests.
2. Wheat, Paddy and suagarcane are generally affected by fungal diseases. Groundnut is affected by Tikka disease. The catterpillars of spotted brown boll worm and Pinkish boll worm affect the crop.
3. A wide variety of agricultural and garden pesticides are available. A few derived from neem tobacco and chrysanthemum (Chamanthi) are less dangerous to other living organisms.
4. A wide variety of inorganic and organic pesticides are commonly used D.D.T. (Dichloro diphenoxy Trichloro ethane) BHC (Benzene Hexa Chloride), Chlordane, Endrin, Aldrin, Endosulfan and Diazinon pesticides are usually dusted or sprayed on crops or put in the soil.
5. But pesticides should not use unwisely. They get into the bodies of plants and animals in the soil and water. When these plants are eaten by animals like fish the pesticide get into their bodies.
6. A bird that eat the fish might get a concentrated lethal dose.
7. D.D.T. also accumulate in the egg shells, weakening them and making the shells break before hatching. It is observed D.D.T. is present in the milk of buffaloes and cows.
8. In this way pesticides are passed down the food chain and accumulate in the bodies of higher animals including human beings causing sickness and sometimes death.

Question 17.
Venkatesh observed the irrigation method for paddy field. He wanted to follow the same practice for his Maize crop. What suggestions do you give him?
Answer:

1. Paddy is grown as a Kharif or a Rabi crop. It requires high temperature of 22°C to 32°C and heavy rain fall. It is cultivated heavily in Kharif season.
2. Maize is cultivated in both Kharif and Rabi seasons but heavily in Kharif season. This requires high temeprature (35°C) with moderate rainfall.
3. So Venkatesh can follow the ame practice for his maize crop as the requirements of both the crops are almost same.

8th Class Biology 8th Lesson Production and Management of Food From Plants InText Questions and Answers

Question 1.
Look at the picture given below and write the constituents in it.

Answer:
Nitrogen (20%), Phosphorus (5%), Potash (10%)

Question 2.
Which manure is beneficial?
Answer:
Natural manure is beneficial.

Question 3.
Let us compare both, which manure is beneficial.

Chemical fertilizers	Natural fertilizers
1. These are made up of inorganic salts.	1. These are made by the decomposition of plants and animal (organic) wastes.
2. These are prepared in factories.	2. These are prepared in open places.
3. No humus can be found.	3. Deposits of humus layer is found in the soil.
4. More amount of Nitrogen, Phosphorus and Potash deposits in the soil.	4. Potash deposits in the soil.

Observe the table carefully, discuss with your teacher and conclude which fertilizer is best to the farmers and why?
Answer:
Natural fertilizer is the best because this is made by the decomposition of plants and animal (organic) waste. Deposits of humus layer is found in the soil with less amount of Nitrogen, Phosphorus and potash deposits in the soil.
a) When do farmers irrigate the land?
Answer:
After applying manure farmers irrigate the land.

b) List out the water resources of your village.
Answer:
Wells, ponds, canals, tanks are the water resources.

c) Are they useful to your farmers?
Answer:
Yes. They are useful.

d) In what way the farmers of your village get water to the fields ?
Answer:
Farmers irrigate their fields either manually using bullocks or by using pumps.

Question 4.
What are the reasons for high production in Japan?
Answer:
Japan has cooler temperature.

Question 5.
What are the reasons for low production in India?
Answer:
High temperature and uncertainty of rainfall.

8th Class Biology 8th Lesson Production and Management of Food From Plants Activities

Activity – 1

Question 1.
CROPS IN INDIA:
Observe the following India map.

a) Are there many crops that are grow in most of the parts of our country? What are they?
Answer:
India is a unique position to grow almost every possible crop. It is the land of producing a variety of cereals like paddy, wheat, jowar, bajra, maize and ragi, pulses, spices, fruits, vegetables, oil seeds, fibre crops etc.

b) Why such crops are grown all over the country?
Answer:
India is an agricultural country and people derive their livelihood from agriculture. Agriculture is the back bone of Indian economy.

c) From the above map, which of them are grown in your village?
Answer:
Rice, pulses, banana, vegetables and leafy vegetables
a) Country: India
b) State: Andhra Pradesh
c) Your village: Khajipalem

d) How many days are required for getting the crop?
Answer:
Nearly 120 days.

e) Is time period for all crops are same?
Answer:
The time peirod for all the crops are not same. They are different from one crop to another.

f) Which crop needs more duration?
Answer:
Rice and Wheat.

Activity – 2

Question 2.
DURATION OF CROP:
a) Write the information in the table.

Name of the crop	Duration of the crop
1. Paddy	3 to 6 months
2. Wheat	110 to 120 days
3. Jowar	5 to 7 months
4. Bajra	100 to 120 days
5. Maize	100 days
6. Raagi	May to Sept., Nov. and Dec.
7. Pulses	90 to 120 days
8. Cotton	165 days

1. Example for long term crops:
Answer:
Jowar, red gram.

2. Example for short term crops:
Answer:
Pulses like green gram, black gram etc., and onions.

Activity – 3

Question 3.
WHERE DO CROPS ARE GROWN.
Discuss in groups and make a list of these things for the following table.

1. In which season do you find more varieties of vegetables in the market?
Answer:
Rainy season.

2. Generally farmers grow varieties of vegetables during rainy season. Can you guess the reason?
Answer:
In rainy season ponds, wells, rivers, ditches are pooled with water.

3. If we cultivate wheat in the month of the November what will happen?
Answer:
We get hot climate from February onwards. It is suitable for maturing the grains. That is the reason wheat is cultivated in the Rabi season only.

Activity – 4

Question 4.
PRODUCTION OF PADDY:
a) Go and collect the information through your nearest farmer and fill the following table.

a) In which season farmers get more benefits?
Answer:
Kharif season

b) Are there any other crops which are growing both Kharif and Rabi seasons?
Answer:
Paddy, wheat and maize

c) In which seasons farmers generally get good quality of seeds.
Answer:
Kharif and Rabi

d) The quantity of grains is higher in Kharif season than Rabi season. Do you agree this? Give your reasons.
Answer:
The climate, (the temperature, humidity with abundance of water supply) will be suitable in Kharif season

e) Do you know about third crop?
Answer:
The third crop season known as Zayad, grown in the months of April, May and June.

Activity – 5

Question 5.
SELECTION OF SEEDS:
Take some water in glass. Drop a fist of seeds in it. You cam observe some seeds will float on water. Collect those seeds and observe with hand lens and comparing with seeds sink under the water. Write your observations in the table.

a) What are the differences you observed in both seeds?
Answer:
Some seeds sank in water, some seeds floated.

b) Do you know why the floated seeds are light in weight?
Answer:
They are unhealthy seeds.

Activity – 6

Question 6.
GERMINATION AND SELECTION:
Show both the seeds in different pots and provide water uniformly, observe the growth of the plants in two pots and make a report.
1. Which seeds germinate well? Why?
Answer:
The seeds which are smooth and round germinate well because they are healthy seeds. Biology

2. Which seeds do not germinate properly? Why?
Answer:
The seeds which are wrinkled and rough do not germinate properly because they are unhealthy.

3. Were all the seeds were tested like this?
Answer:
The crop plant like Rice, wheat etc.

4. Do you know how the paddy seeds germinate?
Answer:
There are different stages in sprouting of the soaked rice seeds before it is planted.

5. Observe a sprout of paddy. Cam you say which part become root? Which part become shoot im the picture?
Answer:
Coleoptile become shoot and the part beneath the ground is root.

Activity – 7

Question 7.
SOWING METHODS
Collect information from the nearby farmers and fill in the table.

1. Why the seedlings are replanted at proper distance?
Answer:
They get water, mineral and sunlight equally when they are replanted at proper distance.

2. Do all the crops grow when replanted? Why not?
Answer:
Mostly all plants will grow.

Activity – 8

Question 8.
CROPS AND DISEASES:
Form a group with 4 to 5 of your classmates, visit nearby field, discuss with farmers about diseases effected by, and how to control them. If you do not know the name of the disease, write its local name or its characters.

1. Do all the farmers use the same pesticides for the same crop?
Answer:
For different crops different pesticides are used.

2. Is there any disease that you find in all fields?
Answer:
No

3. Where do they buy pesticides?
Answer:
From government and private agencies.

4. What are the appliances that they use to spray pesticides?
Answer:
Sprayer or dusters.

5. Did you find any other living organisms dying along with pests due to pesticides ? What are they ?
Answer:
Yes. Caterpillars, sparrows etc.

Activity – 9

Question 9.
IDENTIFICATION OF PESTS:
Observe the plants in a nearby field or in your school garden. Closely observe the leaves and stems to collect the following information. If the character is present put a ‘S’ mark and if there is no character put ‘X’ mark.
Name of the plant/crop : Rice (Blast of Rice)
Place: Prakasam

a. Do all the leaves of plant have spots?
Answer:
Yes, all the leaves of plant have spots.

b. Draw the leaf with these spots.
Answer:

c. What is your reason for the leaves which have cutting edges?
Answer:
Eaten by grasshoppers.

d. Do you find any twilted leaves with insects? How are they?
Answer:
Infection occurs on leaf sheaths.

e. Are the scars on the stems is same as spots on leaves?
Answer:
Yes, the scars on the stems is same as spots on leaves.

f. Collect powdery substance of the spots on leaves and observe under microscope. Write down your observations.
Answer:
Fungus produce small spores known as conidia.

Activity – 10

Question 10.
PEST CONTROLING PRACTICES:
In your village farmers control pests by using different pesticides and insecticides for different crops. For this they use different practices. Ask your elders the names of pesticides that they use in the following pest controlling practices.
Answer:

1. Spraying: Endrin, Diethane, M-45, Eldrine.
2. Dusting: Aldrin, D.D.T.
3. Put in the soil: Zinc, Sulphur, Phosphorous, fluorine
4. Burning and picking are also the practices where they use these: Sugarcane, citrus
5. Bio pesticides: Neem water

Observe the following pest controlling practices
a. Which of the above practices is good?
Answer:
A farmer remove the affected leaves from the plant and burnt them.

b. Why do you think so?
Answer:
By burning the affected leaves the pests will be controlled.

c. Why did the farmer use two pesticides at a time?
Answer:
At the first time the pests will be controlled by spraying pesticide, but if we use unwisely, pests become resistant to the pesticides.

d. What will we do to solve the problem?
Answer:
Pesticides will be used as per the requirement for the disease.

e. Farmers add manure to the soil.
What they used to add?
Answer:
They used to add nutrients to the soil.

f. Have you a compost pit in your school / house?
Answer:
Yes, there is a compost pit in our school. All the waste materials like dry leaves, fruits peel etc. will dump into the pit.

Activity – 11

Question 11.
WHEN SHOULD FARMERS IRRIGATE THE HELD?
Consult to the farmers and fill the table with the information to how and when they provide water to various crops.

a. Are all the crops provided with equal amount of water?
Answer:
No. Irrigation should be done according to nature of the soil and the type of crop to be grown.

b. Why do farmers provide more water to the summer crops?
Answer:
Summer season is the hottest climate so the crops which grow in summer requires high quantity of water.

Weedling:
a. Why should they (weeds) be removed?
Answer:
The weeds compet with the primary crops for nutrients, water and light because of these plants crop plants may not grow properly. So they should be removed.

Question 12.
How sprinklers and drip system are used and write down their merits and demerits.
Answer:
When the availability of water is poor, drip irrigation system is used. In this the water reaches the plant drop by drop through sprinklers. So that water comes out from the sprinklers wetting exactly the place of the roots of the plant.
Advantages:

1. Maximum use of available water.
2. No water being available to weeds.
3. Maximum crop yield.
4. Efficiency use of fertilizers.
5. Less weed growth.
6. Low labour and low operation cost.
7. No soil erosion.
8. Improved infiltration in soil with low in take.

Disadvantages:

1. Sensitivity to clogging.
2. Moisture distribution problem.
3. Salinity hazards
4. High cost compared to furrow.
5. High skills is required for design, install and operation.

Activity – 12

Question 13.
Ask your nearby nursery and know the weeds that grow in different crops. Make a table in your notebook.

Name of the plant	WEEDS
1) Paddy	Garika, Wanza, Varipilla Gaddi, Sukha Bhogi, Dharaka, Buradha, Thunga
2) Vegetable crop	Gunugu, Gaddi Chamanthi, Jeeluga
3) Cotton fields	Puli chinta
4) Mirchi	Puli chinta
5) Tobacco	Pogaku Malle

Harvesting of paddy:
a. If the paddy is not dried well enough. What will happen?
Answer:
If moisture is there in paddy grains it helps to develop moulds (fungi). Such grains neither germinate nor suitable to eat.

b. Where do farmers harvest the crops in your village ?
Answer:
Farmers generally used to harvest by using traditional methods.

c. Is harvesting same for all crops?
Answer:
Yes.

Activity – 13

Question 14.
Find out the methods of harvesting in and around our village and fill the table.
Answer:

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 3 Story of Microorganisms 2 Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 3rd Lesson Story of Microorganisms 2

8th Class Biology 3rd Lesson Story of Microorganisms 2 Textbook Questions and Answers

Improve Your Learning

Question 1.
How do vaccines works in our body?
Answer:
When a vaccine is given which contains weak microorganisms our body learn to fight them by producing antibodies whenever danger comes. When the disease causing microorganisms enter in our body, the already present antibodies fight and eliminate them. And the disease is controlled. The weakened disease causing microorganisms which are injected into our bodies are called as vaccine.

Question 2.
What are the differences between Antibiotic and Vaccine?
Answer:

Antibiotic	Vaccine
An antibiotic is a compound or a substance that inhibits or kills the growth of bacteria.	Vaccine is a preparation that improves the immunity to a particular disease.
An antibiotic heals infection caused by small pox.	A vaccine prevents diseases like polio, bacteria.
Antibiotics are available in different forms like tablets, capsules, drops or ointments.	Vaccines can be given orally or through injection.
Antibiotics are taken after getting infected.	Vaccines are preventive method that is taken before getting infected.

Question 3.
Invention of pencillin protected the world from deaths during first world war, Explain.
Answer:

1. Pencillin was invented by Dr. Alexander Flemming.
2. He was an army doctor in First World War.
3. In the First World War many injured soliders died because of bacterial infection of wounds.
4. Pencillin killed many disease causing bacteria.
5. So the invention of pencillin protect the world from deaths during the first World War.

Question 4.
Take three bowls and mark as A,B,C. Pour lukewarm milk in bowl A, hot milk in bowl B, cold milk in bowl C. Add one tea spoon of curd or butter milk in three bowls and stir them slightly. Cover the bowls with lids. Keep the bowls undisturbed for five to six hours. In which bowl milk turned into curd ? Give your reasons.
Answer:
After six hours the milk in the bowl A converted into curd.
This conversion is happened by fermentation. Fermentaion is one kind of enzy-matic action in anaerobic respiration. Fermentation needs the help of microbes like yeast or some other bacteria. This process occurs at a particular temperature. Be-cause of enzymes are inactive at low and high temperatures. Hence the milk in bowl A converted into curd by the bacterium Lactobacillus.

Question 5.
Collect more information about scientists who invented and discovered other facts related to Microorganisms. How these discoveries helped mankind ? Make a chart presentation and paste it on your classroom wall magazine.
Answer:

Question 6.
Make an album of scientists and their discoveries related to Microorganisms.
Answer:

Question 7.
Visit the veterinary hospital and prepare a list of cattle diseases by asking questions, to the doctor.
Answer:

Disease	Animal
1) African Horse Sickness	Horses
2) Bovine Spongiform Encephalopathy	Cattle
3) Contagious Equine Metritis	Horses
4) Equine Infectious Anaemia	Horses
5) Anthrax	Cattle and other mammals
6) Brucellosis (Brucella abortus)	Cattle
7) Brucellosis (Brucella melitensis)	Sheep and Goats
8) Contagious agalactia	Sheep and Goats
9) Contagious bovine pleuro – pneumonia	Cattle
10) Dourine	Horses
11) European Bat Lyssavirus (FBLV)	Bats
12) Enzootic bovine leukosis	Cattle

Question 8.
What is pasteurisation? What is the use of it?
Answer:

1. Pasteurisation is a process which helps in the preservation of the milk.
2. It is discovered by “Louis Pasteur.” Hence it is called as pasteurisation.
3. In this process milk is heated up to 70° for 15 to 30 seconds and suddenly chilled and stored.
4. This prevents the growth of the microorganisms.

Question 9.
How do you appreciate Edward Jenner’s experiment?
Answer:

Edward Jenner was a man of the Enlightenment and believed in the intellectual and moral improvement of mankind.
Possessing that spirit, he predicted in 1801 that “the annihilation of small pox-the most dreadful scourge of the human race-will be the final result of this practice” of vaccination. And he was right. Since the Enlightenment, the core branches of science and medicine have generally developed rationally. As a result, the World Health Organization was able to declare in 1980 that smallpox had been eradicated worldwide. Only two laboratory samples emained, one in Russia and one in the United States.

Question 10.
Visit a nearby milk chilling centre. Observe the process and make a report on it.
Answer:
The Milk Collection Station is a specially designed, integrated unit, which combines the several functions of a milk collection centre. It measures the weight, fat content and gives the price of the milk brought in by the each producer. The equipment is particularly useful for the milk cooperatives / milk collection centres as it can also maintain a summary of milk supplied. This state of the art equipment operates both on battery and mains and is able to process and record 120-150 milk collection per hour. An Electronic Milk Weighing Unit, the Electronic Milk Tester and Data Processor Unit are main components of the system. The membership code of individual mem¬bers is entered automatically by member identity card / manually by an electronic key-board.

Question 11.
“Prevention is better than cure” comment.
Answer:
We heard about “prevention is better than cure” since our childhood – brushing of teeth twice to prevent tooth decay, washing of hands before eating to prevent stomach upset, do not eat uncovered road side food items, get vaccine against polio to free from disability, get rid of stagnate water to prevent malaria like that follow the life skills to avoid dangerous AIDS. It’s better to take care that a problem does not happen than to have to solve the problem afterwards. It’s easier to stop something bad from happening in the first place than to fix the damage after it has happened.

Question 12.
Raheem tells to his neighbours, “stagnation of’ sewage in our surroundings is harmful to our health. ” Do you support this? Why?
Answer:
Stagnation of sewage in our surroundings is harmful to our health in different ways. Sewage consist different wastes of organic matters. Microbes decompose all organic wastes. Disease transmitting carriers prefer to grow on decomposing organic matters. Hence sewage provides good shelter to mosquitoes, houseflies and other insects which transmit life threatening diseases like encephalitis, malaria, cholera, typhoid and other epidemics. Therefore sewage stagnation is more harmful to our health.

Question 13.
Jeevan said that “If there are no microorganisms earth will remain with wastes. ” Will you agree this statement? Why?
Answer:
Yes, I will agree this statement. Because of:

1. Microorganisms present in the soil, air and water act upon wastes around us.
2. They decomposes them.
3. They are converted into simple substances.
4. Thus microorganisms help us in cleaning the environment.
5. So if there are no microorganisms earth will remain with wastes.

Question 14.
Pranavi is suffering from serious illness. Doctor prescribed antibiotics for five days. After three days of usage she stopped taking antibiotics. Is it right or not, discuss.
Answer:
No, it is not right. Doctor prescribed anitbiotics for five days. Because the doctor knows that the correct days of the recovering of her illness. After three days of usage she stopped taking antibiotics. But her illness is not completely recovered. It is breaking out after some time. So it is not right.

Question 15.
What are the precautions taken to eradicate malaria?
Answer:

1. Malaria is caused by the pathogen piasmodium, is transmitted by female Anopheles mosquito.
   
2. Methods used to prevent malaria include medications, mosquito elimination and the prevention of bites.
3. Using of indoor mosquito repellents, residual sprays, taking care not to store water.
4. Providing awareness how to control mosquito population.

Question 16.
One medical store owner is giving antibiotics to his customer who is suffering from fever without doctor’s prescription? But the customer’s daughter Malathi is telling her father not to take antibiotics without doctor’s prescription. Whom do you support and why?
Answer:
We must use antibiotics prescribed by qualified doctor only. If you use antibiotics without consulting a qualified doctor it may harm us. Unnecessary use of antibiotics affects blood cells which fight infections. Sometimes they may kill useful bacteria too in our intestine and this increases the resistance towards antibiotics.

8th Class Biology 3rd Lesson Story of Microorganisms 2 InText Questions and Answers

Question 1.
What diseases can be prevented if we control mosquitoes?
Answer:
Malaria, Dengue, Chickungunya, Japanese Encephalitis.

Question 2.
Which diseases can we prevented by vaccination?
Answer:
Tuberculosis, Chickenpox, Measles, Polio, Swineflu.

Question 3.
Name the diseases which are transmitted by contaminated water?
Answer:
Cholera, Typhoid

Question 4.
Can you name some diseases which are transmited by Air?
Answer:
Tuberculosis, Chickenpox, Measles, Polio, Swineflu.

8th Class Biology 3rd Lesson Story of Microorganisms 2 Activities

Activity – 1

Question 1.
Take some lukewarm milk in two small bowls. Add a few drops of butter milk or little curd in one of the bowls. In the second bowl do not add anything. Keep the two bowls in a warm place and observe the milk in the bowls after 5 to 6 hours.
a) What changes did you observe?
Answer:
In the first bowl milk changed into curd. There is no change in the second bowl.
b) What is the reason for this?
Answer:
We add curd or butter milk in the first bowl. Curd or buttermilk contain bacterium named lactobacillus. Lactobacillus converts the milk into curd.

Activity – 2

Question 2.
Take 100 grams of maida in a bowl, add one or two spoons of yeast powder, add some water and knead it to make dough. Keep the dough in a warm place. Observe the dough after 3 – 4 hours.
a) What changes do you observe in the dough ?
Answer:
We observe that the dough rises and increase its volume.
b) What might be the reason ? Discuss with your friends and write about it.
Answer:
When yeast is added to the maida dough, the dough rises. This is due to the produc¬tion of carbondioxide gas during the process of fermentation. Bubbles of the gas fill the dough, increase its volume and make it spongy in nature.

Activity – 3

Question 3.
Commercial use of microorganisms.
Take some water in two separate beakers. Add 5 to 10 spoons of sugar to each beaker, then add 2 to 3 spoons of yeast to one of the bowls only. Close both of the bowls with lids and keep them in a warmplace. After 3 to 4 hours remove the lids and smell the contents.
a) What differences did you observe between the two bowls?
Answer:
We feel a new variety of smell from one of the bowls. This is the characteristic smell of alcohol. There is no smell from another bowl.
b) What will be the reason for the odour in yeast mixed bowl?
Answer:
Sugars are converted into alcohol by yeast. This process of conversion of sugars into alcohol is known as fermentation.

Activity – 4

Question 4.
Visit nearby PHC and collect information about vaccination given to 0-15 years chil-dren. Meet a doctor or a health worker and ask what types of vaccines are there ? Which disease can be prevented ? When it should be taken? List them out.
Answer:

Activity – 5

Question 5.
Take two pots or dig two pits in the corner of the garden at home or at your school ground. Fill them up to half with loose soil. Put some biological wastes like fallen leaves, vegetable wastes, waste papers, etc., in one of them. Fill the second one with plastic wastes, polythene bags and with some empty glass bottles.
Answer:
Now cover both the pits with soil and sprinkle water twice a day up to three weeks and observe the changes in both the pits and record.
After three weeks the pit which consists organic wastes decomposed into inorganic matter. But the pit which is filled with polythene bags, plastics and glass bottles is remain same no change is observed. Because of plastics and polythene materials are non biodegradables.

Activity – 6

Question 6.
Meet a doctor of your locality and ask him about the different types of diseases, caused by different microorganisms. Note them down. (OR)
Read the following table and answer the following questions.


Questions:
a) Name the viral diseases that can be prevented by controlling mosquito population.
Answer:
Dengue, Chikungunya, Japanese encephalitis.

b) Which bacterial disease / diseases cannot be controlled by vaccination (acc.to above table) ?
Answer:
Cholera, Typhoid.

c) What would you do to control mosquito population ?
Answer:
Use mosquito repellents, control breeding of mosquitoes by not allowing water stag¬nation in our surroundings.

d) Name the viral disease that spreads through water.
Answer:
Polio.

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 3 Story of Microorganisms 1 Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 3rd Lesson Story of Microorganisms 1

8th Class Biology 3rd Lesson Story of Microorganisms 1 Textbook Questions and Answers

Improve Your Learning

Question 1.
Which organisms are interlinked between living and non-living organisms? Why do you think so?
Answer:
Viruses are an interesting type of microorganisms. They usually made up of crystalized proteins. They behave like nonliving things when they are outside of a living cell. But they behave like living organisms when they are inside host living cells and reproduce just like bacteria. Hence viruses can also call as connecting links between living and nonliving things.

Question 2.
What are microorganisms? Where do you find them?
Answer:
We can see several organisms in our surroundings but we cannot see many of them with our unaided eyes. They can be seen only with the help of microscope only. They are called microorganisms. They can found in air, water, soil and all living organisms.

Question 3.
What type of microorganisms we can observe in pond water?
Answer:
Usually pond water contains bacteria, phytoplanktons, algal members, fungi, rotifers, hydra etc. Collect some pond water with greenish scrapings on a slide and we can observe different algal members like Spirogyra, Chara and Chlamydomonas through the microscope.

Question 4.
Whether microorganisms are useful or harmful. How? Explain.
Answer:

1. Microorganisms are useful and some are harmful.
2. Some microorganisms are useful in formation process, medicine preparation and increase soil fertility.
3. Some microorganisms are harmful by causing diseases and spoling food items.

Question 5.
How are the human actions causing the death of useful bacteria and fungi? What will happen if it continuous?
Answer:

1. Soil is highly rich in microorganisms such a bacteria, fungi, protozoa, micro arthropods.
2. The top eight inches of soil of one acre many contain as much as five and half tons of fungi and bacteria.
3. This is very much useful for growing crops.
4. Excess use of pesticides kills these bacteria.
5. Thus human actions causing death of useful bacteria and fungi.
6. If it happens continue, then it causes to ecological imbalance.

Question 6.
Why the cooked food spoil soon but not uncooked food ? Give your reasons.
Answer:

1. Cooking of food items makes the proteins in the food materials coagulate.
2. It also degrades the protective surface of the food.
3. Thus the cooked foods can be easily inhabited by microoganisms.
4. So they can be spoiled in less time than the uncooked food.

Question 7.
What questions would you like to ask your teacher to know about different shapes of bacteria ?
Answer:

1. Where can we find bacteria?
2. How can we see bacteria?
3. What do we call the round shaped bacteria?
4. What do we call the spring shaped bacteria?
5. What is the name of coma shape bacteria?
6. How many types of bacteria do we find in nature?
7. What is the shape of Lactobacillus bacteria? How is it useful?
8. How is septicemia bacteria harmful?
9. Which type of bacteria is responsible for food poisoning?
10. Which bacteria is present in root nodules of leguminous plants? How do they useful?
11. Name the bacteria that causes leprosy.
12. Which type of bacteria is responsible for tuberculosis?
13. What is the shape of Bacillus thuringiensis bacteria how is it useful to plants?
14. What is the shape of staphylococci bacteria? In what way it affect the health of people?

Question 8.
What will happen if you add buttermilk to chilled milk?
Answer:

1. Lacto bacillus bacteria is responsible for the formation of curd.
2. When we add buttermilk to luke warm milk it takes 2 or 3 hours time to form curd.
3. But if we add buttermilk to chilled milk it takes more time or curd would not form.
4. Curdling indicates that the increase in number of bacteria in milk.
5. In chilled condition the number of bacteria do not increase in number there by curd would not be formed.

Question 9.
How do you observe Lactobacillus bacterium?
Answer:
Take one or two drops of buttermilk on a slide and spread it. Heat the slide slightly on a lamp (3-4 sec¬onds). Add a few drops of crystal violet. Leave it for 30-60 seconds and wash the slide gently with water.
Observe the slide under the Compound Microscope to see the Lactobacillus bacterium.

Question 10.
Visit any bakery or milk chilling center near your school with the help of your teacher or parents. Learn about some techniques to culture and usage of some Microorganisms and prepare a note on them.
Answer:
The Milk Collection Station is a specially designed, integrated unit, which combines the several functions of a milk collection centre. It measures the weight, fat content and gives the price of the milk brought in by the each producer. The equipment is particularly useful for the milk cooperatives / milk collection centres as it can also maintain a summary of milk supplied. This state of the art equipment operates both on battery and mains and is able to process and record 120-150 milk collection per hour. An Electronic Milk weighing Unit, the Electronic Milk Tester and Data Processor Unit are main components of the system. The membership code of individual mem¬bers is entered automatically by member identity card / manually by an electronic key-board.

Question 11.
Observe some permanent slides of microorganisms in your school lab with the help of microscope. Draw its picture.
Answer:

Question 12.
Prepare a model of any microorganism. And write a note on them.
Answer:

Question 13.
Why should we clean our hands with soap before eating ?
Answer:

1. We touch the objects.
2. Microbes are present on them.
3. When we touch them, they will inhabit our hands.
4. Washing our hands with soap kills all the microbes.
5. And makes our hands clean and hygenic.
6. So we should clean our hands with soap before eating.

8th Class Biology 3rd Lesson Story of Microorganisms 1 Activities

Activity – 2

Question 1.
Identify the fungi present, in rotten vegetables.
Answer:
Take some rotten part of vegetable or black spoiled part of bread or coconut with help of a needle on a slide, Put a drop of water. Place a cover slip on it and we can see the following microorganisms through microscope.

Activity – 6

Question 2.
Observe different soil microorganisms through microscope and draw rough sketches.
Answer:
Collect some soil from the field in a beaker or in a glass. Add some water to it and stir it. Wait for some time to allow the soil particles to settle down. Take a drop of water on a slide and we can observe the following microorganisms.

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 2 Cell: The Basic Unit of Life Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 2nd Lesson Cell: The Basic Unit of Life

8th Class Biology 2nd Lesson Cell: The Basic Unit of Life Textbook Questions and Answers

Improve Your Learning

Question 1.
Who discovered the cell for the first time?
Answer:
It was the year 1665 Robert Hooke, a British scientist observed thin slices of cork under a simple magnifying device which he had made himself. He observed that the cork resembled the structure of a honey comb consisting of many empty spaces or empty box like structures. He thought it was made up of very small cavities, Robert Hooke called these cavities “Cell”.

Question 2.
Name the factors on which shape of the cells depend.
Answer:
The shape and size of the cells vary considerably but all of these cells ultimately determined by the specific function of the cells.
e.g.: Amoeba is changing its shape for specific functions like collection of food and locomotion.
The shape of the cell may vary for giving definite structure to the organism, e.g,: Epidermal cells.

Question 3.
Distinguish between unicellular and multi cellular organisms.
Answer:

Unicellular	Multicellular
1) An organism composed of just one cell.	1) An organism composed of more than cell.
2) Many of nature’s simplest creatures called “unicellular organisms”.	2) More biologically advanced creatures, called “multicellular organisms”.
3) Cell is an individual form no gathering to perform tasks, but they live together.	3) Different kinds of cells are joined together to perform specialized tasks.
4) The single cell a unicellular organism possesses, the smaller its body, e.g.: Amoeba, Chlamydomonas.	4) The more cells a multicellular organism possesses, the larger its body, e.g.: Fish, Neem tree.

Question 4.
How will you prepare slide without drying quickly?
Answer:
Preparation of slide is a technique to observe microscopic structures. Microscopic slide is prepared on a 2 mm thick. Thin flat plant material directly placed in a drop of water on the glass slide. A drop of glycerin is added to the water to keep the material for longer time. Glycerine saves the material from drying quickly.

Question 5.
Deekshith said that, “we can’t see cells with unaided eye.” Is the statement true or false? Explain.
Answer:
We can’t see cell with naked eye is true. All living things formed by microscopic cells which are visible through microscope only but the egg of birds is visible without microscope. The size of the cells in living organism may be as small as the millionth of a meter.
Most of the cells either in unicellular and multicellular are small in size to perform all the life processes perfectly. The smallest cell 0.1 to 0.5 micrometers found in bacteria. Some of the cells can be seen with naked eye. The largest cell 17 cm x 18 cm egg of Ostrich.

Question 6.
Correct the statement and if necessary rewrite. (OR)
What is cell wall and what are its functions?
a) Cell wall is essential in plant cells.
b) Nucleus controls cell activity.
c) Unicellular organisms perform all life processes like respiration, excretion, growth and reproduction.
d) To observe nucleus and organelles clearly, staining is not necessary.
Answer:
a) Cell wall is essential in plant cells.
Plant cell walls are essential for plant life and also have numerous industrial applications, ranging from wood to nutraceuticals.
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, in addition to acting as a filtering mechanism. A major function of the cell wall is to act as a pressure vessel, preventing over-expansion when water enters the cell. Cell wall is found in plants, bacteria, fungi, algae, archaea. Animals and protozoa do not have cell walls. “Plant cell wall is an essential component of biotic stress response mechanisms.”

b) Nucleus controls cell activity.
By containing the instructions for protein products in the DNA of the nucleus. All “control” work in the cell is carried out by proteins, such as enzymes, though DNA codes for other structural material, only protein has metabolic and behavioural control in the organism’s cells. Thus, the nucleus is the cell’s control center.

c) Unicellular organism perform all life processes like respiration, excretion, growth and reproduction.
All living organisms perform some basic life processes like respiration, excretion, etc., to sustain its life and improve its race. Unicellular organisms also perform all life processes.

d) To observe nucleus and organelles clearly, staining is not necessary.
To observe nucleus and organelles clearly, staining is necessary. Staining is a technique to get attached color to different parts of a cell. This helps to highlight particular areas in the cell.

Question 7.
Describe the structure of Nucleus.
Answer:
The nucleus is the largest cellular organelle in animals. In mammalian cells, the average diameter of the nucleus is approximately 6 micrometers (pm), which occupies about 10% of the total cell volume.

Question 8.
Explain the functions of Nucleus.
Answer:
Functions:

1. The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle.
2. The nucleus provides a site for genetic transcription that is segregated from the location of translation in the cytoplasm, allowing levels of gene regulation that are not available to prokaryotes.

Question 9.
What is difference between cells in onion peel and cells in Spinach?
Answer:
Cells in onion peel arranged systematically with prominent nucleus. Cells in spinach are in different sizes and shapes without nucleus to perform nutrition.

Question 10.
Label parts of diagrammes given below. And identify which one is plant cell and which one is animal cell.

Answer:
A. Nucleus
B. Cytoplasm
C. Cell membrane
D. Vacuole
E. Nucleus
F. Cell wall
G. Cell membrane
H. Vocuole
I. Vacuole

Question 11.
What questions will you pose to know diversity in cells?
Answer:

1. Are all the cells similar in shape and size?
2. Do you find nuclei in all the cells?
3. How many different types of cells could you see?
4. What are the different shapes of the cells?
5. Do all the cells one of the same in length?

Question 12.
If you want to know about unicellular and multicellular organisms, what questions will you pose?
Answer:

1. What do you mean by unicelluar organism?
2. What do you mean by multicellular organism?
3. Give examples for unicellular and multicellular organisms.
4. What are the differences between unicellular and multicellular organism?

Question 13.
Get some floating slime from a puddle, pick a very small amount of slime and put it on a slide. Separate out one fiber and look at it through the microscope. Draw the diagram what you have observed.
Answer:

Question 14.
Collect different kinds of leaves from your surroundings and observe the shapes of the epidermal cells under microscope. Make a table which contains serial number, name of the leaf, shape of the leaf, shape of the epidermal cells. Do not forget to write specific findings below the table.
Answer:

Question 15.
Make sketches of animal and plant cells which you observed under microscope.
Answer:

Question 16.
Ameer said “Bigger onion has larger cells when compared to the cells of smaller onions”! Do you agree with his statement or not? Explain why.
Answer:
The sizes of the cells in living organisms are too small to be seen with naked eye. The size of the cell is related to its function. The cell has to perform similar function in all living organisms.
The size of the onion depends upon the number of cells and not the size of the cell. Cells are of different shape, size and number.
Hence, I don’t agree with Ameer. “Bigger onions have larger cells when compared to the cells of smaller onions”.

Question 17.
How do you appreciate the fact that a huge elephant, man and trees are made of cells, which are very small and we can look at them through microscope?
Answer:
The size of the cells in living organisms may be as small as the millionth of a meter (micron) or may be as large as a few centimeters. Majority of the cells are too small to be seen with naked eye.
The size of the cell is related to its function. For example, nerve cell both in man and animals are long and branched. They perform the same functions that of transferring message.
The size of the organism is depending upon the number of cells and not the size of the cell. Cells are of different shape, size and number.

Question 18.
Deepak said, “A plant can’t stand erect without cell wall”. Support this statement.
Answer:
Deepak said, “A plant can’t stand erect without cell wall.” We support this statement with the following reasons.
i) Plant cells differ from those of animals in having an additional layer around the cell membrane.
ii) We called if as ‘cell wall’.
iii) Cell wall gives strength and rigidity to planks.
So a plant can’t stand erect without cell wall.

8th Class Biology 2nd Lesson Cell: The Basic Unit of Life InText Questions and Answers

Question 1.
Make different questions to know cells and cell organelles.
Answer:

1. What are the structures present in the cells?
2. Why cells are considered to be structural and functional unit of life?
3. What is the need of cell wall in plant cells?
4. Did we see the cells with naked eye?

Question 2.
Prepare different questions to know the discovery of cell.
Answer:

1. In which year cell discovered?
2. Name the scientist who observed cells.
3. What type techniques used to observe the cell?
4. Is there any special devices used to study the cell?
5. Name the different devices used for discovery of cell.
6. Can we see living cells under the microscope?

Question 3.
Prepare permanent slides of Onion cell, cheek cell and compare practically.
Answer:
Take inner layer of onion and cheek cells. Stain them with saffranin or methylene blue and keep coverslip.
Observe both the slides under microscope. Cell membrane and cell wall is present in both the cells. Dark stained nucleus is presented in the centre of the cell.
Comparison between onion and cheek cells:

Onion cells	Cheek cells
Cells arranged compactly	Cells arranged loosely
Boundary of onion is cell membrane	Boundary of cheek cell is cell wall
Cytoplasm and nucleus is present	Cytoplasm surrounds the nucleus
Cell organelles present in cytoplasm	Cell organelles present in cytoplasm.

Question 4.
Explain diversity in leaf cells practically.
Answer:
Take a section of Neem leaf on the slide and put a drop of water, cover it with a coverslip and observe it under the microscope. We can see different types of tissues present in the leaf. The section of leaf shows the following features.
Three groups of tissues arranged in leaf.
The first group epidermis where the cells are barrel shaped and covered by waxy material for protection.
The second group mesophyll tissue where the cells contain chloroplasts for nutrition. Cells arranged loosely with air spaces and stomata for exchange of gases.
The third group vascular tissue where the cells are thick walled to transport water and food.

Question 5.
Make a sketch of blood cells.
Answer:

Question 6.
Draw a neat diagram of Clilamydomonas.
Answer:

Question 7.
Make a sketch of Amoeba. (OR)
a) Draw a labelled diagram of Amoeba.
b) What are pseudopodia?
Answer:
a)

b) The projections on the body of amoeba which help in locomotion and collecting food.

Question 8.
Have you listened to the words of the cell? Guess how big a cell is? Is the number and sizes of cells in both man and elephant the same? Are the cells of an elephant bigger than that of a man?
Answer:
The size of the cells in living organisms may be as small as the millionth of a meter (micron) or may be as large as a few centimeters. Majority of the cells are too small to be seen with naked eye.
The size of the cell is related to its function. For example, nerve cell in both man and elephant are long and branched. They perform the same functions that of transferring message.
The size of the organism is depending upon the number of cells and not the size of the cell. Cells are of different shape, size and number. Hence size of cells in both elephant and man are same. The number of cells are more in elephant than man.

8th Class Biology 2nd Lesson Cell: The Basic Unit of Life Activities

Activity – 2

Question 1.
Prepare a slide of an onion peel and find out the special characters.
Answer:
Peel an onion and cut out a small fleshy portion from the bulb. Break this into two small parts and try to separate them. We notice a thin film like material holding the pieces together. Take out small portion and spread it evenly on a slide. Cover it with a cover slip and observe it under microscope.
Draw the figure what you have observed.
Cells are arranged side by side without any gaps.

Activity – 4

Question 2.
Observation of the Nucleus in onion peel cells. (OR)
Sahitya is trying to observe the nucleus in the cells of onion peel. Explain the procedure to be followed for the experiment.
Answer:
Peel a membrane an onion now keep this membrane on a slide and add 1-2 drops of the stain (saffranin, methylene blue or red ink). Cover this with a cover slip and leave it for about five minutes. Then add water drop-wise from one side of the cover slip while soaking the extra water with a filter paper from the other side. This will help in washing away the extra stain. Now observe this slide under a microscope. The blue spot observed within the cell is the nucleus.

Activity – 5

Question 3.
Observe the following pictures and answer the questions given below.

i) What are the structures present in the cells ?
Answer:
Cell wall in onion cell and cell membrane in cheek cell.
Cytoplasm and nucleus are common in both the cells.

ii) Did you see a tiny dark stained thing in all the cells ?
Answer:
Yes there is a tiny dark stained nucleus is common in both the cells.

iii) Are they located in the center of the cell in both the cells ?
Answer:
Nucleus located in center of both the cells.

iv) What is the difference between boundary of onion cell and cheek cell ?
Answer:
Cell wall is the boundary of onion and cell membrane is the boundary of cheek cell.

Activity – 6

Question 4.
Collect leaves stems and roots of different plants from the field and take sections to study different types of cells and tissues present in leaf and stems practically.
Answer:
Take a section of grass leaf on the slide and put a drop of water, cover it with a cover slip and observe it under the microscope. We can see different types of tissues present in the leaf.
The section of root or stem shows the following features.
Four groups of cells can be observed.
First group is outermost layer called epidermis.
It protects stem or root externally.
Major portion of stem or root has second group of cells.
This group synthesizes food and preserve food.
Third group of cells transport water and food.
Fourth group of cells placed centrally.

Question 5.
a) Observe the following cells and collect permanent slides.

b) Fill the following table with help of your teacher.

Name of the cell	Shape of the cell	Name of the parts observed in it
RBC	Biconcave	Blood tissue
Smooth Muscle Cell	Rod	Muscles
Nerve Cell	Tree	Brain, spinal cord and nerves
Bone Cell	Star	All bones
White Blood cell	Amoeboid	Blood tissue

i) Are there any similarities in shape of the cells?
Answer:
No similarity is found in the shape and size of the above cells.

ii) Do you find nuclei in all the cells?
Answer:
In human RBC nucleus is absent. Muscle, Nerve, Bone and White Blood Cells consist nucleus.

iii) Do you know, which cell is the longest in all animals?
Answer:
Nerve cell is the longest in all animals.

AP State Syllabus 8th Class Maths Solutions 13th Lesson Visualizing 3-D in 2-D InText Questions

AP State Syllabus AP Board 8th Class Maths Solutions Chapter 13 Visualizing 3-D in 2-D InText Questions and Answers.

8th Class Maths 13th Lesson Visualizing 3-D in 2-D InText Questions and Answers

Do This

Question 1.
Name some 3 – Dimensional objects.   [Page No. 282]
Answer:

1. Cube
2. Cylinder
3. Sphere
4. Cuboid
5. Cone

Question 2.
Give some examples of 2 – Dimensional objects.     [Page No. 282]
Answer:

1. Square
2. Rectangle
3. Line segment
4. Circle
5. Triangle

Question 3.
Draw a kite in your notebook. Is it 2 – D or 3 – D object?      [Page No. 282]
Answer:

Kite is a 2 – D object.

Question 4.
Identify some objects which are in cube or cuboid shape.      [Page No. 282]
Answer:
Shapes of Cube                           Shapes of Cuboid
a) Chalk piece box                       a) Duster
b) Dice                                         b) Cell phone (Cuboidal in shape)
c) Cube shaped cake                   c) Plasma T.V.

Question 5.
How many dimensions that a circle and sphere have?      [Page No. 282]
Answer:
Circle has 2 dimensions.
Sphere has 3 dimensions.

Question 6.
Identify the faces, edges and vertices of given figures.      [Page No. 288]

Answer:

Question 7.
Write the names of the prisms given below:     [Page No. 290]

Answer:
(i) Cube
(ii) Triangular prism
(iii) Pentagonal prism
(iv) Hexagonal prism
(v) Rectangular prism

Question 8.
Write the names of the pyramids given below:       [Page No. 290]

Answer:
(i) Square pyramid
(ii) Pentagonal pyramid
(iii) Hexagonal pyramid

Question 9.
Fill the table:      [Page No. 290]

Answer:

Question 10.
Explain the difference between prism and pyramid.      [Page No. 290]
Answer:
Upper and lower sides of a prism are equal in number. But, in a pyramid the base is a plane and all the edges are coincide in a single point on the top.

Try These

Question 1.
Name three things which are the examples of polyhedron. [Page No. 287]
Answer:

Question 2.
Name three things which are the examples of non-polyhedron. [Page No. 287]
Answer:

Think, Discuss and Write

Question 1.
How to find area and perimeter of top view and bottom view of the given figure.       [Page No. 283]

Answer:
Let the side of each face be ‘1’ unit say.
Shapes of different positions (I)                      Their areas (II)
1. Front view                                                    A = (1 × 1) + (1 × 1) + (1 × 1) = 3 Sq. Units
2. Top view                                                      A = (1 + 1 + 1) × (1 + 1) = 3 × 2 = 6 Sq. Units
3. Bottom view                                                A = (1 + 1 + 1) × (1 + 1) = 3 × 2 = 6 Sq. Units
Perimeters (III)
1. —————>                                             1 + 1 + 1 = 3 Units
2. —————>                                             2(l + b) = 2 (3 + 2) = 2 × 5 = 10 Units
3. —————>                                             2(l + b) = 2 (3 + 2) = 2 × 5 = 10 Units

AP State Syllabus AP Board 8th Class Biology Solutions Chapter 5 Attaining the Age of Adolescence Textbook Questions and Answers.

AP State Syllabus 8th Class Biology Solutions 5th Lesson Attaining the Age of Adolescence

8th Class Biology 5th Lesson Attaining the Age of Adolescence Textbook Questions and Answers

Improve Your Learning

Question 1.
How is adolescence different from childhood?
Answer:

Adolescence	Childhood
1. It is Independent nature and very self conscious.	1. It depends upon parental assistance for basic needs.
2. Adolescents seek company of friends to share their feelings.	2. Children are learning through experimenting and communicating with other.
3. Taking decisions by critical thinking. Don’t like the supervision of elders.	3. Adults supervise and support the development process of child.
4. Lot of Stress and strain.	4. No stress, make new friends and gain new skills.
5. Rate of growth is more	5. Comparatively less.

Question 2.
Write short notes on the following.
a) Secondary sexual characters
b) Adam’s Apple.
Answer:
a) Secondary Sexual characters:

1. In adolescence age some external changes have seen in boys and girls.
2. These are called secondary sexual characters.
3. Example: in boys facial hair, moustaches and beards begin to grow. Hair starts growing on the chest of boys.
4. In girls breast begin to develop.
5. In both boys and girls hair grows in the arm pits.

b) Adam’s Apple:

1. The Adam’s apple is actually a partial growth of our voice box or larynx.
2. The larynx is made up of nine cartilages, one of which is the largest, called thyroid cartilage.
   
3. Due to the elongation of the thyroid cartilage the Adam’s apple is formed. It protrudes out in front of the neck.
4. This is caused mainly by male hormone. Testosterone during adolescence.
5. As a result muscles or chords attached to the cartilage get loosened and thickened.
6. When air passes through these chords a hoarse sound is produced.
7. This is the reason for disturbance in voice in the stage of adolescence. At the end of this stage voice get perfect.

Question 3.
List out the changes in the body that take place at the age of adolescence.
(or)
What are the changes that could be observed in adolescence phase?
Answer:

1. During this adolescence changes occur in external, internal parts of the body.
2. They show interest to spend time with peers.
3. Girls voice becomes soft, pimples also may appear on the face by the activation of oil and sweat glands.
4. There is growth and maturity in reproductive system.
5. In boys voice becomes coarse. Pimples, acne may appear on the face. Facial hair like mustache begin to grow.

Question 4.
Match the following:
1. Testes                                  ( )           a. Estrogen
2. Endocrine gland                  ( )           b. Pituitary
3. Menarche                            ( )           c. Sperm
4.Female hormone                  ( )           d. First menstruation
Answer:
1. c
2. b
3. d
4. a

Question 5.
Why acne and pimples are common in adolescents?
Answer:

1. Naturally in adolescence boys and girls feel worried of their pimples and acne.
2. The reason is the secretions of sweat and sebaceous glands are very active in adolescence.
3. Because of increased activity of these glands in the skin, boys and girls get acne and pimples.

Question 6.
What can you suggest to your classmates to keep himself/herself clean and healthy?
Answer:

1. It would better to have bath atleast twice in a day.
2. All parts of the body and inner wears should be washed and cleaned every day.
3. If cleanliness is not maintained, there are chances of having fungal, bacterial and other unwanted infections.
4. Girls should take special care of cleanliness during the time of menstrual cycle.
5. Making use of disposable napkins.

Question 7.
If you have chance to talk with a doctor, what questions you would ask about adolescent emotions and changes in the body ?
Answer:
If I have chance to talk with a doctor, I would ask about

1. How to develop positive emotions like bravery, self confidence, happiness, satisfaction, appreciation gratitude, concern and forgiveness.
2. And also how to over come the negative emotions like anger, bitterness, dissatisfaction, sadness, anxiety, fear, shame and guilt; which are needed in adolescence.

Question 8.
Some mobile phones have auditory meter to measure frequency of produced sound. By using this phone measure your friend’s voice frequency one from each class VI to X. Report your findings.
Answer:

Name	Class	His/Her Voice Frequency
Madhavi	VI	50 decibels
Kalyan	VII	52 decibels
Ravi	VIII	54 decibels
Hemanth	IX	55.5 decibels
Jalaja	VI	48 decibels
Madhu	VII	48.5 decibels
Padmaja	VIII	49 decibels
Sailaja	IX	49.5 decibels

Question 9.
Write five suggestions to improve the performance of Red Ribbon club of your school.
Answer:

1. To instill life skills.
2. To ensure that every college going youth is equipped with conceptual knowledge about various basic health aspects.
3. To increase the capacity of educational system in teaching various basic health aspects.
4. To motivate youth and build their capacity as peer educators.
5. To promote voluntary blood donations.

Question 10.
Prepare a three minute speech on behavioural changes in adolescents.
Answer:

1. Adolescence is the growing age where we may observe some changes in behaviour.
2. They are very fast in taking decisions.
3. They do not want to be forced to do any work, behave peculiarly sometimes fast and sometimes frigid.
4. Adolescents prefers to spend more times before the mirror and like to use perfumes.
5. They do not want to listen to parents suggestions and feels friends are correct but not parents.
6. They search for identify from teachers and peer groups.
7. They want more independence in taking decisions.
8. Sometimes they feel shy and sometimes feel happy.
9. They try to get romantic relationships.
10. They are more inclined towards unhealthy habits.
11. The adolescents have attraction towards opposite sex.
12. The mind of an adolescent is full of zealous acts and urge to find reasons for several things around.
13. Emotionally they are in a turbulent state all the time they get new thoughts for their life activities.
14. An adolescent feel insecure while trying to adjust to the changes in the body and the mind.
15. They seek company of friends to share their feelings even if they are of opposite sex.

Question 11.
Nature prepares human body to reproduce her generations. What do you think of it?
Answer:

1. In females, the reproductive phase of life begins usually around 10 to 12 years of age.
2. And generally it lasts till the age of 40 – 50 years.
3. The ova begin to mature with the onset of adolescence.
4. One ovum matures and is released by one of the ovaries once in about 28 to 30 days.
5. During this period the wall of the uterus becomes thick so as to receive a fertilized egg.
6. This results in pregnancy and childs’ birth.
7. If fertilization does not occur, the released egg and thickened lining of the uterus will be released with some amount of blood in woman.
8. This is called menstrual cycle.
9. Thus nature prepares the female human body to reproduce generation after generation to continue human life on the earth.
10. This is the secret of nature and is nature’s wonderful phenomena.

Question 12.
You know that early marriage is a social taboo. Prepare some slogans to prevent this. (OR)
You know about that child-marriages are social evil. Your school students are conducting a rally to educate the society. Prepare some slogans on this.
Answer:

1. Avoid child marriage – Prevent childhood.
2. Let a child be a child – stop child marriage.
3. Child marriage – a loosing game.
4. Stop child marriage – stop child abuse
5. Childhood is not for motherhood.
6. Let girls be girls but not brides.

Question 13.
13 years old Swaroop always think of his height. Can he improve his height? What do you suggest him?
Answer:
The suggestion is to take nutritious food and to do body exercise regularly to improve his height.

Question 14.
Are you angry with your parents. How do you wish your parents to be?
Answer:
When insulted or threatened unfairly by parents we get angry on them. In our opinion a parent is

1. to be a good advisor to give advice how to control stress and strain, which is needed by the adolescent.
2. to be like a guide to give guidance how to behave with opposite sex.
3. to be like a friend to give good suggestions.
4. to be like a wellwisher and always stand behind us to lead us for bright future.

Question 15.
What are your expectations about your parents and teachers?
Answer:
Parents and teachers play an important role to develop the adolescents in to healthy, productive young ones to the nation. Parents feel to develop their children in to better ones than themselves. They must have good courage, confidence, boldness, and free to solve the problems. They should not be tense and worse. Parent is to be a friend and guide towards adolescents.
Teacher is not only a master is to be a captain or a leader. Every adolescent needs mental support. Teacher is the only people who give suitable suggestions to make them free from all mental stress.

8th Class Biology 5th Lesson Attaining the Age of Adolescence InText Questions and Answers

Question 1.
Some of you also may behave like this, Why?
Answer:
At the age of 13 – 19 years, some changes like voice becomes hoarse, not caring to follow the suggestions and advises of parents, shows restlessness and growing tall.
Because at this age children will be entering into a period which is called as Adolescence, where some changes in the behaviour is seen.

Question 2.
Have you noticed that you are growing?
Answer:
At the age of adolescence growth in height takes place about 18 years of age both boys and girls reach their maximum height.

Question 3.
Have you reached the age of“Adolescence”?
a) Is mustache growing on your upper lip?
b) Did your voice change?
c) Are hairs growing under arm pit?
d) Are there pimples or acne on your face?
e) Are you taking care of your face by applying powder and combing your hairs frequently?
f) Are you feeling shy when talking with opposite sex?
g) Are you not interested to play with opposite sex which you have done earlier?
h) Are you showing restlessness while your parents suggest to do something?
Answer:
For above all the questions the answer is ‘yes’ during adolescence changes occur in external, internal parts of the body.

8th Class Biology 5th Lesson Attaining the Age of Adolescence Activities

Activity – 1

Question 1.
Observing growth rate.
a) Observe the below table and given graph, answer the following questions.

i) What have you observed from the above table?
Answer:
We have observed the height attained by boys and girls in different ages.

ii) When does growth in height nearly stop?
Answer:
In boy growth in height nearly stops at the age of 18, in girls it stops at 17 years.

iii) Which period of age according to you is the fastest growing period for girls?
Answer:
The fastest growing period for girls is between 14-17 years.

iv) Which period of age is the fastest growing period for boys?
Answer:
The fastest growing period for boys is between 16 to 18 years.

v) Who do grow faster? How can you say?
Answer:
The girls grow faster than the boys. By seeing the above graph, about 17 years of age, girls reach their maximum height.

b) Sneha is 13 years old with 125 cm tall. At the end of the growth period likely to be use the following formulae and calculate the maximum height that Sneha will reach.

Answer:

Sneha’s present height = 125 cm
At the end of the growth period Sneha is likely to be 131.5 cm.

c) Table – 1 shows that girls grow faster than boys in their adolescent period. From a group with six students in your class. Measure the height and calculate the future heights in the following table:
Answer:

Activity – 2

Question 2.
Form five groups in your class. Select at least 15 students. Collect body measurement data of the selected 15 students.
Find an average body measurements for boys and girls separately.
Answer:

Activity – 3

Question 3.
Read the following check list. Put tick (✓) mark which points reflect your behaviour.
Answer:
Check List:

Think & Discuss

I. Read the following information and answer the following questions.
Some sections of people in our society believe that during the period of menstruation women are untouchable. So, they are asked to keep a distance from others. During this time girls may be ristricted from taking bath, cooking food or going to school. In that case they may lag behind in their studies. In some sections of the society even women are also forced to stay in the huts built at the outskirts of the village.

Question 1.
In what way this kind of discrimination is harmful for girls and women?
Answer:

1. During the period of menstruation women are treated as untouchable by some sections of people in our society.
2. Generally during this period they feel weak and uncomfortable physically.
3. By this kind of discrimination, mentally also they get hurt and feel that why they have born as woman.
4. By separation, it would be known to all by this the girl may feels shy, unable to move freely with others and she becomes dull in studies.

Question 2.
Several researches have been done to prove that all these are myths and there is no scientific reason behind these. The blood and egg that is discarded would give rise to a baby if fertilization took place. This is a biological phenomena.
So how can it be impure or unclean?
Answer:

1. If fertilization took place, the uterus receives a fertilized egg and this results in pregnancy and would give rise a baby which develops in the uterus.
2. If fertilization does not occur this cause bleeding in woman, which is the unwanted and waste to the uterus. So it can be treated as impure or unclean and may create some problems in uterus.
3. During menstrual period proper care regarding health and hygiene is needed rather than following myths.

Question 3.
If young generation is trapped into such unhealthy habits, what will be the
future of our country ? What are its effects?
Answer:

1. If young generation is trapped into unhealthy habits like consuming tobacco (gutkha, cigarettes, cigar, beedi) they addicted to such social evil.
2. Todays children are tomorrows citizens so it should be avoided.
3. A famous psychiatrist Stanly Hall stated that adolescence is the age of stress and strain. By getting proper guidance from teachers, parents and elders, the adolescents be able to lead a happy meaning full life and they will save the future of the country.

AP State Syllabus 8th Class Maths Solutions 12th Lesson Factorisation InText Questions

AP State Syllabus AP Board 8th Class Maths Solutions Chapter 12 Factorisation InText Questions and Answers.

8th Class Maths 12th Lesson Factorisation InText Questions and Answers

Do this

Question 1.
Express the given numbers in the form of product of primes. [Page No. 267]
(i) 48      (ii) 72      (iii) 96
(i) 48
Answer:
48 = 2 × 2 × 2 × 2 × 3

ii) 72
Answer:
72 = 2 × 2 × 2 × 3 × 3

iii) 96
Answer:
96 = 2 × 2 × 2 × 2 × 2 × 3

Question 2.
Find the factors of following:      [Page No. 268]
(i) 8x²yz     (ii) 2xy (x + y)       (iii) 3x + y³z
Answer:
i) 8x²yz = 2 × 2 × 2 × x × x × y × z
ii) 2xy (x + y) = 2 × x × y × (x + y)
iii) 3x + y³z = (3 × x) + (y × y × y × z)

Question 3.
Factorise:      [Page No. 270]
(i) 9a² – 6a
(ii) 15a³b – 35ab³
(iii) 7lm – 21lmn
Answer:
(i) 9a² – 6a = 3 × 3 × a × a – 2 × 3 × a
= 3 × a (3a – 2)
∴ 9a² – 6a = 3a (3a – 2)

ii) 15a³b – 35ab³
= 3 × 5 × a × a × a × b – 7 × 5 × a × b × b × b
= 5 × a × b [3 × a × a – 7 × b × b]
= 5ab [3a² – 7b²]

iii) 7lm – 21lmn
= 7 × l × m – 7 × 3 × m × n × l
= 7 × l × m [1 – 3n]
= 7lm [1 – 3n]

Question 4.
Factorise:
i) 5xy + 5x + 4y + 4
ii) 3ab + 3a + 2b + 2 [Pg. No. 271]
Answer:
i) 5xy + 5x + 4y + 4
= (5xy + 5x) + (4y + 4)
= 5x(y + 1) + 4(y + 1)
= (y + 1) (5x + 4)

ii) 3ab + 3a + 2b + 2
= [3 × a × b + 3 × a] + [2 × b + 2]
= 3 × a [b + 1] + 2 [b + 1]
= (b + 1) (3a + 2)

Think, Discuss and Write

While solving some problems containing algebraic expressions in different operations, some students solved as given below. Gan you identify the errors made by them? Write correct answers.     [Page No. 279]
Question 1.
Srilekha solved the given equation as shown below.
3x + 4x + x + 2x = 90
9x = 90 Therefore x = 10 What could say about the correctness of the solution?
Can you identify where Srilekha has gone wrong?
Answer:
Srilekha’s solution is wrong,
∵ 3x + 4x + x + 2x = 90
10x = 90
x = \(\frac{90}{10}\)
∴ x = 9

Question 2.
Abraham did the following.      [Page No. 280]
For x = -4, 7x = 7 – 4 = -3.
Answer:
Abraham’s solution is wrong.
∴ If x = -4
⇒ 7x = 7(-4) = -28

Question 3.
John and Reshma have done the multiplication of an algebraic expression by the following methods: verify whose multiplication is correct.      [Page No. 280]

Answer:

∴ John’s solutions are wrong and Reshma’s solutions are correct.

Question 4.
Harmeet does the division as (a + 5) ÷ 5 = a + 1 His friend Srikar done the same (a + 5) ÷ 5 = a/5 + 1 and his friend Rosy did it this way (a + 5) ÷ 5 = a Can you guess who has done it correctly? Justify!     [Page No. 280]
Answer:
The solutions of Harmeet, Rosy are wrong.
(a + 5) ÷ 5 = \(\frac{a+5}{5}\)
= \(\frac{a}{5}\) + \(\frac{5}{5}\)
= \(\left(\frac{a}{5}+1\right)\)
∴ Srikar had done it correctly.