TS 10th Class Biology Study Material 9th Lesson Our Environment

Telangana SCERT 10th Class Biology Study Material Telangana 9th Lesson Our Environment Textbook Questions and Answers.

TS 10th Class Biology 9th Lesson Questions and Answers Telangana – Our Environment

Question 1.
What happens to the amount of energy transferred from one trophic level to the next in a food chain?
Answer:

• Energy is transferred along food chains from one trophic level to the next.
• But not all of the energy available to organisms at one step can be absorbed by organisms at the next one.
• The amount of available energy decreases from one stage to the next.
• This is because, not all the food can be fully digested and assimilate.
• Hair, feathers, insect exoskeletons, cartilage and bone in animal foods, cellulose and lignin in plant foods cannot be digested by most animals.
• These materials are either ejected by defecation or regurgitated in pellets of indigested remains.
• Assimilated energy is available for the synthesis of new blomass (which is food for the next tropic level) through growth and reproduction.
• But organisms lose some biomass by death, disease or annual leaf-drop.
• Moreover, at each tropic level, organisms use the most of the assimilated energy to fulfill their metaboLic requirements – performance of work, growth and reproduction.
• As biological energy transformations are Inefficient, a substantial proportion of metabolized food energy is lost unused as heat.
• Only a small fraction goes to the eater at next tropic level.
• SLobodkin (1959) suggested that the transfer of energy from one tropic level to the next is of the order of 10%. But in 1974, Steele proved it to be 20 to 30%.

Question 2.
What do pyramids and food chain indicate in an ecosystem?
Answer:

• The pathway along which food is translerred from one organism to another in an ecosystem is called a food chain.
• Food chain shows that how energy passed from one organism to another.
• Apart from the food chain, pyramids are another type of representations which show flow of energy from one organism to another.
• Ecological pyramids are the graphical representation of the feeding level structure of an ecosystem by taking the shape of a pyramid.
• Pyramid of number indicates the population of organisms at each tropic level of a food chain in an ecosystem.
• Pyramid of biomass indicates the available food (biomass) as a source of energy at each tropic level of a food chain in an ecosystem.
• Pyramid of energy indicates the available energy at each tropic level of a food chain in an ecosystem.

Question 3.
Write a short note on pyramid of numbers for any food chain. What did you conclude from the pyramid of numbers drawn using:
(i) tree
(ii) insects
(iii) woodpecker
Answer:
a.

• The number of organisms in a food chain can be represented graphically in a pyramid of number.
• Each bar represents the number of individuals at each tropic level in a food chain.
• At each link in a food chain, from the first-order consumers to the large carnivores, there is normally an increase in size, but decrease in number.
• For example in a wood, the aphids are very small and occur in astronomical numbers.
• The ladybirds which feed on them are distinctly larger and not so numerous.
• The insectivorous birds which feed on the ladybirds are larger still and are only present in a small numbers, and there may only be a single pair of hawks of much larger size than the insectivorous birds on which they prey.

b.

• In the given pyramid, the producer is a large tree, primary consumers are small insects which are numerous in number and secondary consumers are woodpeckers which are comparatively less in number than insects.
• From this pyramid of number, we can conclude that sometimes the pyramid of numbers does not look like a pyramid at all.
• This could happen If the producer is a large plant or if one of the organisms at any tropic level is very small.
• Whatever the situation, the producer still goes at the bottom of the pyramid.

Question 4.
Draw the pyramid of biomass using the terms given below:
(i) grass
(ii) herbivores
(iii) predators
(iv) hawk
Answer:

• Biomass is organic material of biological origin that has ultimately derived from the fixation of carbon dioxide and the trapping of solar energy.
• This includes trees, shrubs, crops, grasses, algae, aquatic plants, agricultural and forest residues and all forms of human, animal and plant waste.
• Any type of plant or animal material that can be converted into energy is called “Biomass”.

Question 5.
How does the usage of toxics substances affect an ecosystem’? Write a short note on bioaccumulation and biomagnification.
Answer:

• Use of toxic materials such as pesticides, herbicides and fungicides creates new problems in the ecosystem.
• As these toxic materials are often indiscriminate in their action and vast numbers of other animals may be destroyed.
• Some of them may be predators which naturally feed on these pests, other may be the food for other animals.
• Thus causing unpredictable changes in food chains and upsetting the balance within the ecosystem.
• Some toxic substances have a cumulative effect.
• These toxins vary in their length of life as toxic substances.
• Some of them are degradable, can be broken down into harmless substances in a comparatively short time usually a year.
• Others are non – degradable which are potentially dangerous as they accumulate in the bodies of animals and pass right through food web.
• Being further concentrated at each step until animals at the top of pyramid may receive enough to do considerable harm.
• This process of entering of pollutants in a food chain is known as “Bioaccumulation”.
• The tendency of pollutants to concentrate as they move from one tropic level to the next is known as “Biomagnifications”.

Question 6.
Should we use pesticides to protect the crops and foods from pests? Or should we think of alternatives’? Write your opinion and the reasons for it.
Answer:

• We should think of alternatives. This is because, these pesticides are toxic chemical whose usage leads to Bioaccumulation and ßiomagnificatiofls.
• When we use pesticides they prevent our crop and food from pests effectively but indiscriminately destroys a vast number of other animals.
• This is causing unpredictable changes in food chains and upsetting the balance within the ecosystem
• Most of the chemical pesticides that contain mercury, arsenic or lead are non – degradable.
• They enter into food chain, accumulate in the bodies of animals and pass right through food web.
• Being further concentrated at each step until animals at the top of pyrâmtd may receive enough to do considerable harm.
• This may lead to the danger of extermination of some of our larger and more attractive species.
• This is one of the reasons for ever decreasing number of butterflies, bees, small and large birds.
• The adverse effect of pesticides on birds was proved by the studies of Royal Society for the protection of birds.
• Some of the pesticides are nerve poisons and might bring about changes in behaviour.
• As the human beings are at the end of the food chain, these pesticides may get accumulated in our bodies also. This shows some adverse effects on us, when their concentration becomes sufficiently high.

Question 7.
What is a trophic level? What does it represent in an ecological pyramid
Answer:

• Trophic level is the feeding position in a food chain.
• In an ecological pyramid, the first trophic level represents the primary producers, and their number, biomass or energy.
• Second trophic level represents the herbivores or primary consumers and their number, biomass or energy.
• Third trophic level represents the lower carnivores or secondary consumers and their number, biomass or energy.
• Fourth trophic level represents the higher carnivores or tertiary consumers, and their number, biomass or energy.

Trophic Levels:

II level carnivores — IV level
↑
I level carnivores — III level
↑
Herbivores — II  level
↑
Producers — I level

Question 8.
If you want to know more about flow of energy in an ecosystem, what questions do you ask?
Answer:
I will ask the following questions to know more about flow of energy in an ecosystem.

• How does the energy flow in an ecosystem from one organism to other?
• Is the energy transformation from one level to other 100% efficient?
• What percent of energy transfers from one level to other?
• What happens to the remaining energy?
• How does the ecosystem lose its energy during energy transformation?
• Which tropic level in an ecosystem has more energy and which has less?
• What is the ultimate source of energy in an ecosystem?

Question 9.
What will happen if we remove predators from food web?
Answer:

• Removal of organisms from any tropic level of a food chain or food web disturbs the ecosystem and leads to ecological imbalance.
• If we remove predators from food web, the prey population will increase enormously as there is no natural control over them.
• The producers population will decrease rapidly as the organisms feeding on them increase.
• After few generations the prey population also begins to decrease as some of the preys begin to die due to starvation.
• Some adaptations may also be developed by the organisms to bring the ecological balance.
• But it may take some generations, till that the ecosystem will be disturbed and imbalanced.
• For example if we remove all the predators (carnivorous) from a forest ecosystem, the h herbivorous animal population will increase as there are no carnivores to hunt them.
• As a result plant population will decrease as the ever-increasing herbivores feed more and more on plants.
• After some generations the herbivore population begins to decrease as the decreasing number of plants are not sufficient to feed.
• Then some herbivorous animals may adapt to feed on other herbivores to increase their survival.
• Then scope for survival will increase for plants again which leads to ecological balance.
  But this may take lot of time to evolve new predators and to form ecological balance.

Question 10.
Observe a plant in your kitchen garden, and write a note on producer-consumer relationship.
Answer:
When I observe a plant in kitchen garden, I came to know the following things.

• Though it may be relatively small, a garden is a complete ecosystem.
• It has the same components as any other large and elaborate ecosystems had.
• The plant in a kitchen garden is a producer as it produces their own food from sunlight.
• There are two types of consumers in this ecosystem.
  a. Primary consumers and
  b. Secondary consumers.
• Primary consumers feed on plants. This tropic level consists of caterpillars, bees and butterflies.
• Secondary consumers feed on primary consumers. This tropic level consists of birds, garden lizards and spiders.
• Fungi, bacteria, insects and worms make up decomposers.
• The producer and consumer relationship can be shown in the following food chain.
• Producers → Primary consumers → Secondary consumers
• The pyramid of number appears like this.
  
• The pyramid of Biomass appears like this
  
• The pyramid of energy appears like this
  

Question 11.
Collect information on laws and ethics concerned to the environment and display it on bulletin board.
Answer:

• We should have profound respect for Nature.
• We must maintain a hormonious relationship with other species.
• Everyone should take responsibility for his impact on nature.
• Local and indigenous environmental knowledge should be respected.
• We must plan long term.
• The Environment Protection Act (1986) enacts to protect and improve environmental quality, control and reduce pollution from all sources. The Hazardous waste rules (1989) controls the generation, collection, treatment, import, storage and handling of hazardous wastes. The Biological Diversity Act (2007) enacts to provide sustainable use of conservation of biological chemistry.

Question 12.
Draw a pyramid of numbers considering yourself as a top level consumer. Write about the lower trophic levels.
Answer:
The pyramid of numbers considering humans as top level consumer looks like a upright pyramid. There will be increase in the numbers from top to bottom. Man feeds on various animals like goat and birds like chicken, etc. These animals inturn feed on large number of insects and worms, or some herbivores can directly feed on plants. The lower tropic can directly feed on plants. The lower trophic layer consists of plants in larger numbers which produce energy. People who feed on the plants are called vegetarians and just lay above the first trophic level.

Question 13.
Prepare slogans to promote awareness in your classmates about ecofriendly activities.
Answer:

• Live and let live.
• If we protect environment, it protects us.
• Conserve nature – Conserve life.
• Save mother earth.
• Earth needs you.
• Go ecofriendly.
• Clean the environment, live happily.
• Heal our planet ! Turn into a better planet.
• Plant a tree for your environment.
• Think ecofriendly and live ecofriendly.
• Earth enables you to definitely stand. Allow it to stand the actual way it is.
• You’ve only got one planet. Don’t trash it.
• Say no to plastic.
• Encourage Bio-fertilizers,

Question 14.
Suggest any three programmes on avoiding pesticides and preventing soil pollution.
Answer:
Pesticides are the toxic chemicals which are used to destroy pests. They not only disturb the ecosystem but also pollute the soil. To prevent soil pollution caused by pesticides following programmes should be implemented.
i. Rotation of crops
ii. Biological pest control
iii. Development of genetic resistant strains.

i. Rotation of crops:

• Same crop should not be grown in the same field in successive seasons.
• As the pest which grows on one crop never grows on the other, they can be kept under control naturally.

ii. Biological pest control:

• In this method pests are controlled by some biological processes, instead of using chemical pesticides.
• Using predators, using hormones like pheramones, sterilization of the insect pests and utilisation of biological pest repellents such as neem oil etc., are some of the biological pest control methods.

iii.  Development of genetic resistant strains:

• Nowadays using genetic engineering pest resistant strains are being produced.
• If we use these, crops never get effected by the pest, so no need to use pesticides.

Choose the correct answer:

Question 1.
What does a food chain always start with?
A. The herbivore
B. The carnivore
C. The producer
D. None of these
Answer:
C. The producer

Question 2.
Which of the following do plants not compete for?
A. Water
B. Food
C. Space
D. All above
Answer:
B. Food

Question 3.
Ban all pesticides, this means that ……………
A. Control on usage of pesticides
B. Prevention of pesticides
C. Promote ecofriendly agricultural practices
D. Stop biochemical factories
Answer:
C. Promote ecofriendly agricultural practices

Question 4.
According to Charles Elton
A. Carnivores at the top of the pyramid
B. Energy trapping is high at the top of the pyramid
C. No producers at the top of the pyramid
D. A and C
Answer:
D. A and C

TS 10th Class Biology 9th Lesson Our Environment Intext Questions

1 Mark Question and Answers :

Question 1.
Name any two pesticides / insecticides you have heard about.
Answer:
DDT, Aidrin, Malathian, Altrazine, Monocrotophos, Endosuiphan, etc.

Question 2.
Where do the pollutants enter the water sources from?
Answer:
The used water from industries and run off water containing agricultural effluents bring pollutants into water sources. Municipal and domestic sewage also pollute water sources.

Question 3.
How do heavy metals enter the fishes living in this water?
Answer:
The bioaccumulation of heavy metals in tissues of fish particularly in liver, kidney and gills were analysed and found their presence.

Question 4.
What is the food chain that has been discussed in the above case?
Answer:
The food chain discussed in the above occurrence is
Crops → Locust → Sparrow Hawk.

Question 5.
How did these disturbances affect the environment?
Answer:

• The number of locust increased.
• Use of pesticides against locust population further degraded the land.

Question 6.
Is it right fo eradicate a living organism in an ecosystem ? How is it harmful?
Answer:

• No, it is not right to eradicate a living organism in an ecosystem.
• It disturbs the existing food chain.

Question 7.
Were the sparrows really responsible ? What has the reason for the fall in crop production?
Answer:

• No, the sparrows were not really responsible for the loss of food grain.
• With no sparrows to eat the locust population crops were damaged and this led to fall in crop production.

Question 8.
What was the impact of human activities on the environment?
Answer:

• The human activities badly affected the environment.
• Use of pesticides against the pest degraded the landutions

2 Mark Question and Answers :

Question 1.
Are all terrestrial ecosystems similar?
Answer:
1) No. Ail the terrestrial ecosystems are not similar.
2) Based on variations in climatic conditions such as rainfall, temperature and the availability of light, there are various kinds of ecosystems.
3) The major types of terrestrial ecosystem are :

• Tundra
• Coniferous forest
• Deciduous forest
• Savannah
• Tropical forest and
• Deserts.

Question 2.
Why do most of the food chains consist of four steps?
Answer:

• Most of the food chains are quite short and mostly consistS of four steps.
• This is because only 10% of the energy present in a level transfers to the other level.
• Remaining energy is dissipated as heat produced during the process of respiration and other ways.
• Thus about three steps in a food chain very little energy is still available for use by living organisms.

Question 3.
Why do the number of organisms get decreased as we move from producer to different level of consume’s
Answer:

• As we move from producers to different levels of consumers the energy available will decrease gradually.
• Only ten percent of the energy present in one tropic level transfer to another tropic level.
• Biomass also decreases gradually as only 10 – 20% of the biomass is transferred from one tropic level to the next in a food chain.
• As there is less energy & less biomass available at top levels number of organisms also less, generally.
• So, the number of organisms get decreased as we move from producer to different level of consumers.

Question 4.
How are the food grains and cereals being stored in your house and how do you protect them from pests and fungus?
Answer:
To protect food grains and cereals from pests and fungus, we will follow the following rules in our house.

• First of all we will dry and clean our grain before storing.
• We will avoid moisture in bagged grains by storing them on wooden structures, bamboo mats or polythene covers.
• We use domestic bins or improvised storage structures such as Gaade, Kotlu, Paatara, RCC bins and flat bottom metal bins etc.
• We fumigate the storage room with Ethylene Di-bromide (EDB) ampoules to avoid insect damage.
• We use anticoagulants for rat control in houses.

Question 5.
Researchers found that pollution levels increase during monsoon season. Why they found so?
Answer:

• Pollution levels increase during monsoon season in water bodies.
• During monsoon season heavy rainfall occurs.
• The rain water brings residues of agrochemicals fertilizers and different types of organic substances, municipal and domestic sewage.
• Hence pollution levels increase in monsoon season.

Question 6.
Why did people living in the areas nearby the water reservoir, suffer from various diseases?
Answer:

• The heavy metals could find their way into human beings through food chain.
• This bioaccumumation cause various physiological disorders such as hypertension 1 sporadic fever, renal damage, nausea, etc.

Question 7.
How did the campaign disturb the food chain in the fields?
Answer:

• Crop yields after the campaign were substantially decreased.
• Though the campaign against sparrows ended it was too late.
• With no sparrows to eat the locust populations, the country was soon swarmed.
• Locust coupled with bad weather led to the great Chinese famine.

Question 8.
What do you suggest to stop/avoid such incidents?
Answer:

• I suggest to use organic manures and organic insecticides to kill the Insects.
• Rotation of crops is the best method to protect the crops from pests.
• We should not kill any organism on this earth because every organism has a role to play.
• Think before you start action.

Question 9.
What did scientists find in the sparrow campaign? Did they help in rectifying / correcting the mistake ? Why didn’t they do it so?
Answer:
During the sparrow campaign some scientists cut open the digestive systems of dead sparrows and found only one-fourth contained grains. This finding showed that sparrows are benificial birds for humans. This ended the campaign against sparrows but it was too late. There were no sparrows to eat the locust populations which led to the great Chinese Famine.

4 Mark Question and Answers :

Question 1.
If we want to show a food chain consisting of grass, rabbit, snake and hawk then connect the given picture of organisms by putting arrows and make a food chain.
A. Name the producers and consumers in the above food chain.
B. Try to guess what the arrows marked by you indicate.
C. Identify at least four other food chains from your surroundings. Name the producers and different levels of consumers in those food chains.
Answer:
Grass → Rabbit → Snake → Hawk
A. In the above food chain grass is the primary producer. Rabbit is the primary consumer, snake is the secondary consumer and hawk is the tertiary consumer.

B. The arrows indicate the flow of energy from one organism to another. So these are always pointed from the food to the feeder.

C.

• Plant → insect → frog → snake
• Aquatic plants → insects → fish → crane
• Plant → mice → snake → vulture
• Plant → aphids → spiders → birds

Question 2.
Draw the pyramid of number for the following food chains.
i. Banyan tree insects woodpecker
ii. Grass → rabbit → wolf
A. Does the pyramid of number have the same structure in both the cases as compare to the example given in the textbook?
B. If there is a difference, then what is it?
Answer:

A. No. The pyramid of number in the above two cases doesn’t have the same structure as compared to the example given in the textbook.

B.
1. In the example (given in the textbook), number of organisms at producers level is more. This number gradually decreased in consumers level step by step. So the pyramid of number formed has typical pyramid shape with broad base and the narrow apex.

2. But in the first case given here, on a single Banyan tree, a large number of insects live and feed. These insects become food for few Woodpeckers. So producers number is less than primary and secondary consumers, and secondary consumers are less than primary consumers. So the pyramid of number does not look like a pyramid. It consists of narrow base, broad middle part and medium apex.

3. In the second case, Grass which are large in number become food for few rabbits. Rabbit provides food for several wolf which are comparatively less in number than grass. So primary consumers are less in number than secondary consumers and producers. So the pyramid of number for this food chain also does not look like a pyramid. It consists of broad base, narrow middle part and medium apex. Thus it differs from case (1) also.

Question 3.
Think why the pyramids are always upright?
OR
Why are the pyramids always upright?
Answer:

• In ecology not all the pyramids are always upright.
• Pyramid of number may be upright, inverted or partly upright.
• Pyramid of biomass may be upright or inverted.
• But the pyramid of energy is always upright.
• This is because energy will decrease when we move from producers to the high level consumers.
• Only 10% of the energy from one tropic level transfers to the other through food chain.
• So the energy at base is more, gradually decreases, and very less at the top.
• As a result the energy pyramid is always upright.

Question 4.
Observe the data given in the following table.
Answer:

i. In which year lake-water spread area is more? Why?
Answer:
In the year 1967. Because lake was brought under cultivation.

ii. Why do you think weeds are more dense in the lake?
Answer:
Excessive nutrient addition, especially from anthropogenic sources, led to explosive weed growth. Ex: Eichornia, Pistia.

iii. What are the reasons for decrease in lake area?
Answer:

• ln 1996, almost entire lake was brought under cultivation.
• Industries came along in ever growing intensity in the catchment area of the lake.

iv. How do the above said reasons lead to pollution?
Answer:

• Consequently, the drains and rivulets carry substantial quantity of various types of pollutants into the lake.
• The major sources of pollution are agricultural runoff containing residues of several agrochemicals, fertilizers, fish tank discharges, industrial effluents containing chemical residues.

v. What could be the reasons for the migration of birds to this lake?
Answer:
To avoid extreme cold weather conditions in Northern Asia and Eastern Europe birds migrate to Kolleru lake.

vi. How was the threat to the lake due to pollution discovered?
Answer:

• The water of the lake turned alkaline in nature, turned, nutrient rich, low in dissolved oxygen and high in biochemical oxygen demand.
• Water borne diseases like diarrhoea, typhoid, amoebiasis and others are said to be common among the local inhabitants who are unaware of the state of pollution in the lake water.
• Vector-borne diseases also increase.

Question 5.
Observe the following table showing different activities in the lake and their influence.
Answer:

Legend: (+) means has influence on the mentioned problem
(-) means has no influence on the mentioned problem

i. What are the factors that affected the number of migratory birds to decrease?
Answer:
Aquaculture practices.

ii. Do you find any relationship between biological and physical problems ? What are they?
Answer:
Yes. Aquaculture practices have influence on these problems.

iii. What are the reasons for chemical problems?
Answer:
Agricultural practices, aquaculture practices, industrial activities and human activities are the reasons for chemical problems.

iv. What happens if the dissolved oxygen reduces in lake water?
Answer:
If the dissolved oxygen reduces in lake, water, then the water turned more alkaline in nature. Organisms die due to lack of sufficient amounts of oxygen.

v. Is BOD of turbid and nutrient rich water high or low? What are its consequences?
Answer:
High organisms in water die its consequences are water borne diseases.

vi. People living encatchment area of Kolleru faced so many problems. Why?
Answer:
Vector borne disease increased. The lands abandoned are useless for agriculture.

vii. How does pollution influence the migration of birds?
Answer:
Due to pollution the water of the lake turned more alkaline in nature, turbid, nutrient rich, low in Dissolved Oxygen (DO) and high in Biological Oxygen Demand (BOD).
This increased, a number of vector borne diseases. A large number of fishes are endangered. This decreases the migration number of birds.

TS 10th Class Biology 9th Lesson Our Environment Activities

Observe any (water) ecosystem In your surroundings and identify the different food chains and food web operating in this ecosystem. Write the following details in your notebook.

1. Names of the students in a group : ………………….. Date : …………………..
2. Name of the ecosystem : …………………..
3. Topography : …………………..
4. Names / Number of plants (producers) identified : …………………..
5. Names / Number of animals identified : …………………..
6. Identify the different types consumers and name them & mention their number below:
Herbivores (Primary consumers) : …………………..
Carnivores (Secondary consumers) : …………………..
Top carnivores (Tertiary) : …………………..
7. Food relationships among them: food habits / preferences : …………………..
8. Show / draw the different food chains : …………………..
9. Showcase the food web I : …………………..
10. List out all abiotic factors existing in the ecosystem : …………………..
(A check list can be given, and asked to tick)
11 . Is there any threat to the ecosystem ? Yes / No : …………………..
If yes, what ? and how ? : …………………..
Suggest few remedial measures : …………………..

A. Student’s Activity.