TS 10th Class Biology Important Questions 2nd Lesson Respiration

These TS 10th Class Biology Chapter Wise Important Questions 2nd Lesson Respiration will help the students to improve their time and approach.

TS 10th Class Biology Important Questions 2nd Lesson Respiration

1 Marks Questions

Question 1.
Fermented idli, dosa produces smell. Name the microorganism responsible for producing such smell?
Answer:
Yeast is responsible for producing such smell in fermented idli, dosa

Question 2.
In what compound, the energy released during the breakdown of glucose, is stored?
Answer:
“ATP” (Adenosine Triphosphate).

Question 3.
Label a and b in the given diagram.

Answer:
a. Matrix
b. Cristae.

Question 4.
Name chemical substances produced in human muscles during Anaerobic respiration.
Answer:
Lactic acid is produced in human muscles during Anaerobic respiration.

Question 5.
Why Diazene Green solution is added to the glucose solution in anaerobic respiration experiment?
Answer:
Diazene Green solution is added to the glucose solution in anaerobic respiration experiment to check the presence of oxygen in glucose solution.

Question 6.
Name the food material on which trypsin acts and name the end products.
Answer:

• protein
• end products – peptones.

Question 7.
Identify the figure.
Answer:

Aerial roots in Mangrove plants.

Question 8.
“Respiration is the energy releasing process.” Write your opinion on this statement.
Answer:
The given statement is absolutely correct. We respire to use the oxygen to oxidise our food and release energy. This is similar like burning but a slower process. With the help of respiratory enzymes, energy released can he stored in the form of ATP for later use.

Question 9.
Can we say that combustion and respiration are almost same actions. What evidences do you have for this ?
Answer:

• In both these processes sugar is converted to carbon dioxide and water.
• Both these processes require oxygen
• Both combustion and respiration releases energy.

Question 10.
What is the role of epiglottis in respiration and swallowing food ?
Answer:
The epiglottis is a flexible flap at the superior end of the pharynx in the throat. Epiglottis acts as a lid over glottis and prevents food from entering into larynx. Air from pharynx enters the larynx while food enters into oesophagus.

Question 11.
What is the pathway of air from nostril to alveolus ? mm
Answer:
Nostrils  Nasal cavity  Pharynx  Larynx  Trachea  Bronchus  Bronchioles  Alveolus  Blood.

Question 12.
What is respiration ?
Answer:
Respiration is the process by which food is broken down for release of energy.

Question 13.
What does the respiration mean ?
Answer:
It means ‘to breathe’ in Latin.

Question 14.
Who did comprehensive work on properties of gases, their exchange and respiration ?
Answer:
Lavoisier and Priestly.

Question 15.
What was the gas liberated on heating powdered charcoal in a hell jar 2
Answer:
It was fixed air. In those days carbon dioxide was known as fixed air.

Question 16.
What was produced by combustion according to Lavoisier ?
Answer:
Carbon dioxide.

Question 17.
What is vitiated air ?
Answer:
A term used then to show air from which the component needed for burning had been removed.

Question 18.
Which gas, according to Lavoisier, is respirable air ?
Answer:
Oxygen.

Question 19.
Who was the renowned chemist ? Who wrote a textbook of Human Physiology ?
Answer:
John Daper.

Question 20.
What happens when air passes through nasal cavities ?
Answer:

• Air is filtered in nasal cavity’ by mucus lining and the hairs growing from its sides remove some of the tiny particles of dirt in the air.
• The temperature of the air is brought close to that of the body.

Question 21.
What is the function of epiglottis ?
Answer:
Epiglottis controls the movement of air and food towards their respective passages.

Question 22.
Where does gaseous exchange take place?
Answer:
Gaseous exchange takes place in tiny air sacs of lung called Alveoli.

Question 23.
What is breathing?
Answer:

• Breathing is the process of inhaling and exhaling.
• The mechanism by which organisms obtain oxygen from the environment and release carbon dioxide is called breathing.

Question 24.
What is inspiration or inhalation?
Answer:
Entry of air into lungs from outside is inspiration.

Question 25.
What is expiration or exhalation?
Answer:
It is the pushing out air from lungs to outside.

Question 26.
What are pleura?
Answer:
Pleura are the two membranes that protect lungs from injury.

Question 27.
What is cellular respiration?
Answer:
Oxidation of glucose or fatty acids takes place In the cells and releasing energy. Hence this process is known as cellular respiration.

Question 28.
What is aerobic respiration?
Answer:
Oxidation of glucose in presence of oxygen is called aerobic respiration.

Question 29.
What is anaerobic respiration?
Answer:
Respiration in absence of oxygen is called anaerobic respiration.

Question 30.
Where does aerobic respiration occur in eukaryotic cells?
Answer:
Cytoplasm and Mitochondria.

Question 31.
What is Glycolysis?
Answer:
It is the breakdown of glucose molecule into two molecules of 3 carbon compound called pyruvic acid or pyruvate releasing energy.

Question 32.
What is the fate of pyruvate in the absence of oxygen in plants?
Answer:
In the absence of oxygen pyruvate will be converted to ethanol, CO₂ releasing energy in plants.

Question 33.
What is the fate of pyruvate in the absence of oxygen in animals?
Answer:
In the absence of oxygen pyruvate will be converted to lactic acid releasing small amount of energy.

Question 34.
In aerobic respiration pyruvate is converted into?
Answer:
If oxygen is available pyruvate is oxidized to CO₂ and water releasing large amount of energy.

Question 35.
What is the main reason for feeling pain in muscles after strenuous exercise?
Answer:
Due to the anaerobic respiration in muscles large amounts of lactic acid is accumulated and this results in muscular pains.

Question 36.
What is fermentation?
Answer:
In the absence of oxygen, yeast cells convert pyruvic acid to ethanol. This process is called fermentation.

Question 37.
What is the method used to separate ethanol from the yeast glucose mixture in anaerobic respiration?
Answer:
By Fractional distillation method.

Question 38.
What is combustion?
Answer:
Combustion is a process in which heat is released when organic molecules (sugar) are burnt, CO₂ and H₂O are released.

Question 39.
In which organisms exchange of gases takes place through diffusion?
Answer:
Amoeba, hydra and planarians.

Question 40.
In tracheal respiratory system which carry air directly to the cells in the tissues?
Answer:
Trachioles, the fine branches of trachea.

Question 41.
In fishes what are the respiratory organs?
Answer:
Gills or bronchiae.

Question 42.
What is cutaneous respiration?
Answer:
If the respiration occurs through skin, it is known as cutaneous respiration. e.g: Leech, Earthworm and Frog.

Question 43.
What are the other areas on the plant body through which gaseous exchange take place?
Answer:
It is through the surface of roots, lenticels on stem.

Question 44.
What is the full form of ATP ? How is it formed?
Answer:

• ATP stands for Adenosine triphosphate.
• The energy released during respiration process is used to make an ATP molecule from Adenosine diphosphate (ADP) and inorganic phosphate (P).

Question 45.
Whatis the use of ATP?
Answer:

• ATP is the energy currency for most cellular process.
• ATP is used to supply energy in the cells for carrying all the metabolic processes.

Question 46.
What are the factors that control respiration?
Answer:
Oxygen and temperature are the two important factors that control the process of respiration.

Question 47.
What are the substances that are used for the production of energy in all living organisms?
Answer:
Glucose and fatty acids are used for the production of energy.

Question 48.
How many types of respiration are present? What are they?
Answer:
There are two types of respiration. They are

• Aerobic respiration
• Anaerobic respiration.

Question 49.
Where is energy stored in ATP?
Answer:
Energy is stored in the terminal phosphate bond in ATP which is having three phosphates attached to a molecule of Adenosine.

Question 50.
What are the power house of the cell?
Answer:
Mitochondria are the power house of the cell.

Question 51.
What is the main difference between respiration and combustion?
Answer:
In respiration several intermediates are produced and in combustion there are no such intermediates are produced.

Question 52.
What are the end products of aerobic respiration?
Answer:
CO₂ and H₂O are the end products of aerobic respiration.

Question 53.
What is the equation that represents respiration?
Answer:
C₆H₁₂O₆ + 6O₂ → 6 CO₂ + 6H₂O + 686 KCal.

Question 54.
What are the sites of cellular respiration?
Answer:
Mitochondria are the sites of cellular respiration.

Question 55.
What are cristae in mitochondria?
Answer:
The inner membrane of mitochondria is thrown into several folds called cristae.

Question 56.
What is the net gain of ATP molecules in Glycolysis?
Answer:

• Four ATP molecules are produced when one molecule of glucose is converted to two molecules of pyruvate but two are consumed.
• The remaining two ATP molecules are net gain in glycolysis.

Question 57.
What are the number of ATP molecules produced when one glucose molecule is completely oxidised?
Answer:
A net gain of 38 ATP molecules are formed from the total oxidation of one glucose molecule.

Question 58.
What are the three stages present in complete oxidation of glucose molecule?
Answer:

• Glycolysis
• Krebs cycle
• Electron transport.

Question 59.
Why does oxidation of fatty acids give more energy?
Answer:
Oxidation of fatty acids gives more energy due to the presence of more carbon atoms in them.

Question 60.
What is meant by aquatic animals and terrestrial animals?
Answer:
Animals that live on land are known as terrestrial animals and animals that live in water are called aquatic animals.

Question 61.
Why is the rate of breathing in aquatic organisms much faster than terrestrial organisms?
Answer:
The amount of dissolved oxygen in water is low as compared to the amount of oxygen in air, therefore the rate of breathing in aquatic animals is much faster than in terrestrial animais.

Question 62.
Which part of roots is involved in the exchange of respiratory gases?
Answer:
The respiration in roots occurs by the diffusion of respiratory gases through root hairs.

Question 63.
Name the areas in a woody stem through which respiratory exchange of gases takes place.
Answer:
In woody stems, the bark (outer covering of stem) has lenticels for gaseous exchange.

Question 64.
Out of photosynthesis and respiration in plants which process occurs all the time and only at daytime?
Answer:
Respiration occurs all the time and photosynthesis occurs only at daytime.

Question 65.
The trachea divides into two tubes at its lower end What is the name of these tubes?
Answer:
Bronchus.

Question 66.
What is the average breathing rate in an adult man at rest?
Answer:
The average breathing rate in an adult man at rest is about 15 to 18 times per minute.

Question 67.
Why is trachea prevented from collapsing?
Answer:
The wails of the trachea are supported by several ‘C’ shaped cartillagenous rings.
They prevent the trachea from collapsing and closing.

Question 68.
What has raised the percentage of carbon dioxide in exhaled air?
Answer:
During oxidation of glucose carbon dioxide is produced as waste product. Hence the concentration of carbon dioxide increases in exhaled air.

Question 69.
What are the reasons for the animals to develop different types of respiratory organs?
Answer:
Body size, availability of water, habitat in which they live and the type of circulatory system are some of the reasons for the animals to develop different types of respiratory organs.

Question 70.
Why do fishes die when taken out of water?
Answer:
This is because fishes do not have lungs to utilise the oxygen of air for breathing and respiration. They have gills which can extract and dissolve oxygen from water for survival.

Question 71.
What would be the consequences of deficiency of haemoglobin in our bodies?
Answer:
Deficiency of haemoglobin in blood can affect the oxygen supplying capacity of blood in body cells. It can also lead to a disease called Anaemia.

Question 72.
Which gas did you think is Lavoisler talking about when he says chalky acid gas?
Answer:
It is carbon dioxide.

Question 73.
What is the composition of inhaled air?
Answer:
Inhaled air contains 21% of oxygen, 0.04% carbon dioxide and 79% of nitrogen.

Question 74.
What is the composition of exhaled air?
Answer:
Exhaled air contains 16% of oxygen, 4% of carbon dioxide and 79% of nitrogen.

Question 75.
Why does the amount of nitrogen not vary between exhaled and inhaled air?
Answer:
Because nitrogen has no role to play in respiration.

Question 76.
In which kind of respiration more energy is released?
Answer:
In aerobic respiration more energy around (686 KCal) is released than in anaerobic respiration (58 KCal).

Question 77.
Which gases are exchanged in your lungs?
Answer:
Oxygen and carbon dioxide.

Question 78.
The bark of woody plants is dead but the inner layers inside the bark are living.
OR
How do they get oxygen and release carbon dioxide?
Answer:
Through lenticels.

Question 79.
What are lenticels?
Answer:
Lenticels are portions of the periderm (bark) with numerous intercellular spaces. Their purpose is to allow gas exchange through the compactly arranged cork cells of the bark, which otherwise presents an impermeable barrier to the passage of water and gases.

Question 80.
How does diaphragm help in inhalation?
Answer:
It flattens during inhalation, thus increasing the volume of the thoracic cavity.

Question 81.
Name the type of respiration in which the end products are
a. C₂H₅OH and CO₂
b. CO₂ and H₂O
c. Lactic acid.
Answer:
a. Anaerobic respiration in yeast
b. Aerobic respiration
c. Anaerobic respiration in muscles.

Question 82.
“If there were no algae, there would be no fish in the sea” Comment.
Answer:
Algae produce oxygen as a result of photosynthesis. This oxygen is utilised by the fishes in the sea for carrying out respiration. If there were no algae, no oxygen would have been produced. Thus fishes might have died.

2 Marks Questions

Question I.
What happens if there is no epiglottis in human beings?
Answer:

• Food may enters into the larynx.
• Food may enters into the lungs leading to the death.
• May not speak properly.
• Entry of food and air may not he regulated properly.

Question 2.
Write two chemicals and two materials required to conduct the experiments “Heat and Carbon dioxide are evolved during anaerobic respiration”.
Answer:
Materials required : Thermosflask, splitted corks, thermometer, wash bottle, glass tubes.
Chemicals required : Liquid paraffin, glucose solution, bicarbonate solution, Janus green B and Yeast cells.

Question 3.
Observe the below diagram.
A. This picture is related to which biosystem?
B. Write the names of the parts of A, B.
C. To which system they are linked with?
D. Which process is happening here?
What happens as a result of it?
Answer:

A. Respiratory system.
B. A – alveolus; B – blood capillary network
C. Respiratory system; circulatory system.
D. Gaseous exchange between alveolus of lungs and blood capillaries. Due to this the CO₂ present in blood capillaries enter alveolus and oxygen present in alveolus enter blood capillaries.

Question 4.
A person reached a specific distance once on foot and once by running. In which situation his legs pain ? Why?
Answer:

• When a person rules to reach a specific distance gets pain in his legs.
• This is due to the production of lactic acid in the muscles.
• The sugar ¡n the working muscles when a person runs was being changed to lactic acid.
• Accumulation of lactic acid results pain in leg muscles.

Question 5.
What is the advantage of the wet and warm passage of air from the nostrils to capillaries?
Answer:
The foist surface of the lining of the nasal cavity and the hair growing from it sides, remove some of the tiny particles of dirt in the air. In addition as the inhaled air passes through the nasal cavity, its temperature is brought close that of the body and it takes up water vapour so that it becomes more moist than before. Warming and moistening is goes on in the pharynx and also throughout the respiratory tract.

Question 4.
In the experiment of anaerobic respiration with yeast
i. Why was liquid paraffin poured on glucose?
ii. What did you understood about anaerobic respiration?
Answer:
i. The supply of oxygen from the air can be cut off by pouring liquid paraffin on glucose.
ii. Anaerobic respiration takes place in the absence of oxygen. In this glucose molecule is incompletely oxidised. The end products of anaerobic respiration are ethyl alcohol or lactic acid and CO₂.

During anaerobic respiration small amount of energy is liberated (2ATP). Anaerobic respiration occurs in many anaerobic bacteria and human triuscies cells. The anaerobic respiration can he represented as:
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₆+ 56 K.Cal.

Question 5.
See the below table. Write what you know from it.
Answer:

Gas	% in inhaled air	% of exhaled air
Oxygen	21	16
Carbon dioxide	0.04	4
Nitrogen	79	79

Answer:

• The inhaled air consists of 21% of oxygen whereas the exhaled air contains 16% of oxygen only. ‘[his is due to utlilisation of oxygen during cellular respiration in the body. Hence the difference occurs.
• inhaled air contains 0.04% of carbendiuxide whereas exhaled air contains 4% of carbondioxide. The concentration of CO₂ is increased a lot due to the release of CO₂ during cellular respiration in the body.
• Both inhale and exhale air contains 79% of nitrogen because nitregen has no role to play in cellular respiration.

Question 6.
How does the respiration in amoeba and hydra occur through diffusion? What are the similarities in respiration of amoeba and hydra?
Answer:

• Amoeba and hydra are aquatic organisms.
• Respiration in them occurs through diffusion.
• As oxygen is used by these organisms in respiration its concentration is reduced in cytoplasm and hence oxygen diffuses into cytoplasm from surrounding water.
• Due to respiration CO₂ is continuously produced, its concentration increases in the cytoplasm, hence it diffuses into surrounding water.

Question 7.
What are different ways in which glucose is oxidised to provide energy in various organisms?
Answer:
Breaking down of glucose involves two processes. In the first step, it is broken into three carbon molecules called pyruvate. The pyruvate is further broken down into energy in following different ways in various organisms.

• Aerobic respiration : In this case pyruvate is broken town into water and carbon dioxide along with release of energy. It commonly occurs in mitochondria of cells.
• Anaerobic respiration in yeast : In yeast cells during fermentation pyruvate is converted into ethanol and CO₂ in the absence of O₂
• Anaeorbic respiration in muscles: Due to lack of oxygen. eg. during vigorous running or exercise, in human muscles, pyruvate is converted to lactic acid.

Question 8.
How does respiration in plants differ from that iii animals?
Answer:

• In plants all parts like root, stern, leaves, etc., perform respiration individually, while in animals either the general body surface or specific organs like skin, gills, lungs, etc., are involved in respiration.
• The rate of respiration is much slower in plants than in animals. Unlike animals there is little transport of gases from one part of the plant to another.

Question 9.
Write about respiration in mangroves that grow in marshy lands.
Answer:

• Mangroves grows near the marshy places respire through aerial roots or respiratory roots.
• The root hairs exchange the gases from their surface.
• They obtain oxygen from the airspaces present between the soil particles.
• The plants grows in marshy places are adapted to develop aerial roots above the soil surface which helps in gaseous exchange.

4 Marks Questions

Question 1.
Explain different steps In respiration in human beings.
Answer:
Different steps in respiration in human beings.

Breathing : Air movement into and out of lungs.
Gaseous exchange at lungs level: Exchange of gases between alveoli and blood.
Gas transport by blood : Transport of oxygen from blood capillaries of alveoli to
blood cells and return of carbon dioxide.
Gaseous exchange at tissue level : Exchanging of oxygen from blood into the cells and
carbon dioxide from cells into the blood.
Cellular respiration: Using oxygen in cell processes to produce carbon dioxide and
water, releasing energy to be used for life processes.

Question 2.

observe the above diagram and answer the following questions:

i. What does the above setting (diagram) indicate?
Answer:
The above setting (diagram) indicate to prove that carbon dioxide and heat are liberated during anaerobic respiration by yeast cell.

ii. Why boiled and cooled glucose is covered with paraffin?
Answer:
To prevent supply of air boiled arid cooled glucose is covered with paraffin.

iii. What is the use of adding diazime green to glucose solution ? What change you notice in glucose solution?
Answer:
Diazine green is added to glucose solution to know whether oxygen is present or not in glucose solution. When the availability of oxygen is less the diazine green changes to pink colour.

iv. Why lime water is used lu this experiment?
Answer:
To know whether carbon dioxide is released or not in this experiment lime water is used. Carbon dioxide changes lime water to milky white.

v. Why bulb of thermometer is dipped in the glucose water?
Answer:
To know the rise in temperature of glucose solution when heated, the bulb of thermometer is dipped in the glucose water.

Question 3.
Study the graph and answer the following questions:
Graph showing effects of vigorous excercise on the concentration of lactic acid in blood.
on the concentration of lactic acid in blood.
i. What was the concentration of lactic acid in blood to start with?
ii. What was the greatest concentration of lactic acid reached during the experiment?
iii. What is the concentration of lactic acid after 25 minutes of exercise?
iv. What is the relationship between lactic acid and muscle pain?
Answer:

i. 20mg/cm³
ii. 20 minutes (Or) at ‘B” point.
iii. 101 mg/cm³
iv. If concentration of lactic acid increases muscle pains also increases.

Question 4.
Explain with the help of a flow chart, the pathway of air in humans.
Answer:

Question 5.
Observe the following:

Write the answers to the following questions:

i. How many Pyruvic acid molecules form from one Glucose?
Answer:
2 Pyruvic Acid molecules.

ii. What conditions influences Pyruvic acid to participate in Aerobic and Anaerobic respiration?
Answer:
Presence of oxygen

iii. In which we get more energy in both Aerobic and Anaerobic respiration?
Answer:
Aerobic respiration

iv. The chemical that is formed in human muscles during Anaerobic respiration.
Answer:
Lactic Acid

I. Conceptual Understanding

Question 1.
Describe the structure of mitochondria with the help of a diagram.
OR
Which cell organelle is called energy currency or power house of cell?
OR
What do you know about its construction?
Answer:
Structure of mitochondria:

• Mitochondria is known as energy currency or powerhouse of cell.
• Mitochondria can be seen with a special microscope called electron microscope.
• Mitochondria are sac-like structures present in the cytoplasm of the cells.
• They may be of various shapes thread-like, spherical.
• Mitochondria have two compartments – an two compartment and zin outer compartment. The substance in the inner compartment is called matrix.
• The matrix is surrounded by a membrane called inner membrane of mitochondria.
• The inner membrane is thrown into several folds called cristae. The cristae extended into the matrix.
• The space between the folds is continuous with the outer compartment.
• The outer compartment is surrounded by another membrane – the outer membrane. The outer membrane is smooth and has no projections.
• The inner membrane, the matrix and the elementary particles in the mitochondria have large number of enzymes and other required proteins for the respiration and energy production.

Question 2.
Why the exchange of gases happens only in alveoli, though arteries are present in pharynx, trachea and bronchus?
Answer:
Alveoli have several adaptations to maximize the efficiency of gas exchange. They fold to provide a wider surface area for gas exchange to take place and they are ventilated to remove carbon dioxide and to replenish oxygen levels in the alveolar air.

This maintains maximum concentration gradient which refers to the difference in the concentration of a chemical across a membrane, between the air in the alveoli and blood. The alveoli have thin walls that are one cell thick to make the exchange surface extremely thin.

Question 3.
Describe how oxygen enters the blood in lungs with the help of block diagram?
OR
How gaseous exchange occurs in lungs?
Answer:

• Gaseous exchange takes place within the lungs by diffusion from the alveoli to blood capillaries and vice versa. Alveoli in lungs are numerous and only one cell thick.
• Alveoli are surrounded by capillaries that are also one cell thick
• Blood, dark red in colour flows from the heart through these capillaries and collects oxygen from the alveoli. At the same time, carbon dioxide passes out of the capillaries and into the alveoli.
• When we breathe out, we get rid of carbon dioxide.
• The bright red, oxygen rich blood is returned to the heart and pumped out to all parts of the body.

Question 4.
What is the role of diaphragm and ribs in respiration ? Are both active in man and woman ?
OR
Is respiration possible without diaphragm and ribs in human? Explain.
Answer:

• Diaphragm is a muscular dome shaped tissue present at the floor of the chest cavity separating abdomen from respiratory system.
• Diaphragm expands downwards into the abdomen thus increasing chest cavity. This allows the lungs to expand as we inhale.
• As the diaphragm contracts upwards thus decreasing the chest cavity, it allows the air to expel from the lungs.
• The ribs protect the lungs and expand as we inhale to facilitate space for the lungs to expand. The ribs then contract expelling the air in the lungs.
• The intercostal muscles present between the ribs help in contraction and relaxation of ribs.
• In man, diaphragm plays a major role in the respiration, while in woman, the ribs play a major role.

Question 5.
Explain the process of transportation of gases through the blood.
Answer:
1. The relative amount of gases and their combining capacity with haemoglobin and other substances in blood determine their transport via blood in the body.

2. When oxygen present in the air is within normal limits (around 21%) then almost all of it is carried in the blood by binding to haemoglobin, a protein present in the red blood cells.

3. As oxygen is diffused in the blood, it rapidly combines with the haemoglobin to form oxyhaemoglobin.

4. Not only haemoglobin can combine with oxygen, but the reverse can also happen to yield a molecule of haemoglobin and oxygen.

5. Carbon dioxide is usually transported as bicarbonate, while some amount of it combines with haemoglobin and rest is dissolved in blood plasma.
Hb + 4O₂ → Hb(O₂)₄ (in lungs)
Hb(O₂)₄ → Hb + 4O₂ (in tissues)

Question 6.
What are the different ways in which glucose is oxidised to provide energy in various organisms ? Give one example of each.
Answer:

• Glucose is the most commonly used sugar for deriving energy in plants, animals and in micro-organisms.
• In all these organisms glucose is oxidised in two stages.
• The first stage is known as Glycolysis. It occurs in cytoplasm.
• During glycolysis glucose is converted to two molecules of pyruvic acid.
• In the second stage, if oxygen is available pyruvic acid is converted to CO₂ and water, large amount of energy is released. This is known as aerobic respiration. In most of the plant and animal cells aerobic respiration occurs.
• If oxygen is inadequate or not available, pyruvic acid is converted into ethanol and carbon dioxide. This is anaerobic respiration. taking place in yeast cells that is called fermentation.
• If oxygen is not available in muscle cells, the pyruvic acid is converted into lactic acid.

Question 7.
Write a brief note on respiration in plants.
Answer:

• In most plants exchange of gases takes place through stomata.
• There are other areas on the plant body as well, through which gaseous exchange takes place like surface of roots, lenticels on stem, etc.

• Some plants have specialized structures like, breathing roots of mangrove plants as well as the tissue in orchids.
• Breathing roots and tissue in orchids help plants to take oxygen to produce energy and carbon dioxide is released.
• Inside the plants stomatal openings lead to a series of spaces between the cells which form a continuous network all over the plant.
• The whole system works by diffusion.
• As the oxygen is used up by the cells a gradient develops between the cells and the air in the spaces and similarly between the air spaces and the air outside stomata and lenticels, so oxygen passes in.
• In the same way, as more carbon dioxide is given out by the cells, a gradient occurs in the reverse direction and it passes out.

Question 8.
Write the adaptations seen in plants living in water logged conditions.
Answer:

• Most plants can aerate their roots by taking in the oxygen through lenticels or through the surface of their root hairs.
• But plants which have their roots in very wet places, are unable to do this.
• They are adapted to these water logged conditions by having much larger air spaces which connect the stems with the roots, making diffusion from the upper parts much more efficient.
• The problem of air transport is more difficult for trees and many not survive with their roots permanently in water.
• An exception is the mangrove tree of the tropics which sends up aerial roots above the surface and takes in oxygen that way.

Question 9.
Write a brief note on tracheal respiration in insects.
Answer:

• In insects blood has no haemoglobin and is white in colour. Hence it cannot carry oxygen.
• For respiration insects adopt a special system called tracheal system.
• This system consists of a series of tubes called trachea.
• These trachea open out through small apertures called spiracles on either side of the body.
• All tracheal tubes of each side join and form a longitudinal tracheal trunk.
• Trachea divide into a number of branches called tracheoles which carry air directly to the tissues.
• As the air moves in and out of the trachea, oxygen present in the air diffuses into the cells and CO₂ diffuses into the air from the cells.

Question 10.
Write about the mechanism of respiration in human beings.
Answer:

• Respiration in man occurs in two stages. They are inspiration and expiration.
• During inspiration air from outside enters into the lungs by increasing the thoracic cavity.
• lncrease in the thoracic cavity is made by pulling the diaphragm down and pushing the ribs forward.
• As the air pressure in the lungs is reduced, air from outside enters the lungs through external nostrils, nasal cavities, pharynx, epiglottis, larynx, trachea, bronchi and bronchioles and finally reach the alveoli where exchange of gases takes place.
• During expiration the diaphragm and ribs come back to original positions.
• This reduces the volume of thoracic cavity.
• So the volume of lungs is decreased and air under lressure comes out of the lungs.

Question 11.
Explain the evolutionary changes in energy releasing system.
Answer:

• Exchange of gases is a common life process in all living organisms, but it is not same in all.
• Single celled organisms amoeba or multicellular organisms like hydra and planarians obtain oxygen and expel carbon dioxide directly from the body by the process of diffusion.
• In multicellular animals special organs are evolved.
• Animals either terrestrial or aquatic adopted different types of respiration and different types of respiratory organs mostly due to the habitat in which they live.
• Body size, availability of water and the type of circulatory system are some of the reasons for the animals to develop different types of respiratory organs.
• In insects tracheal respiratory system is present in which small branches of trachea called tracheoles carry air directly to the cells in the tissues.
• In fishes gills are utilised for the exchanges of gases. Blood is supplied to gills through capillaries which have thin walls for exchange of gases. This is called bronchial respiration.
• Respiration through skin is called cutaneous respiration.
• This type of respiration is seen in earthworm and leeches.
• Frog, an amphibian can respire through cutaneous pulmonary processes.
• Most of the higher animals respire with the help of lungs. This type of respiration is known as pulmonary respiration.

Question 12.
Describe the structure of human lungs with the help of a diagram.
Answer:

• A pair of lungs is present in the chest cavity one on either side of the heart.
• Lungs are spongy and elastic and are enclosed by two membranes called pleura.
• Space between the two membranes of Pleura is filled with fluid. Pleura protects the lungs from injury.
• Right lung is larger than the left lung.
• Right lung is made of three lobes while the left lung has only two lobes.
• Lung has several thousands of alveoli which are supplied with blood capillaries.
• Pulmonary artery brings deoxygenated blood from heart to lungs.
• After entering the lung. this artery divides into several arterioles and capillaries and supplies deoxygenated blood to alveoli.
• Gas exchange occurs in the alveoli.
• Oxygenated blood is carried from the lung to heart by the pulmonary vein.

III. Experimentation And Field Investigation

Question 1.
What are the experiments carried out by Lavoisier to understand the property of gases ?
Answer:

• In his early experiments Lavoisier thought that the gas liberated on heating powdered charcoal in a bell jar kept over water in a trough was like fixed air i.e., carbon dioxide.
• The next series of experiments deals with the combustion of phosphorus in a bell jar. From this he showed that whatever it was in the atmospheric air which combined with the phosphorus was not water vapour.
• This was respirable air, a component of air that also helped in burning.
• The air that we breathe out precipitated lime water while that after heating metal did not.
• From this he concluded that there were two processes involved in respiration.
• Lavoisier carried out another experiment by which he showed that about one-sixth of the volume of vitiated air’ consists of chalky acid gas (fixed air).
• Either eminently respirable air is changed in the lungs to chalky acid air; or an exchange takes place, the eminently respirable air being absorbed, and an almost equal volume of chalky acid air being given up to the air from the lungs.
• Lavoisier had to admit that there were strong grounds for believing that eminently respirable air did combine with the blood to produce the red colour.

Question 2.
Study the graph given below and analyse the reasons for accumulation of lactic acid in blood after strenuous exercise.
Answer:

Answer:

• The graph shows the analysis of blood of a person during and after exercise.
• The athlete taking part in the experiment had to stay still where the apparatus was.
• He pedaled a stationary bicycle, or ran on a tread mill.
• Some results are shown in the graph.
• Vigorous exercise lasted for nine minutes (shown by the bar at the base of the diagram) and regular blood samples were taken and analysed.
• One particular compound in the blood, lactic acid, was found to vary greatly in its concentration as we see from the graph.

IV. Information Skills and Projects

Question 1.
Observe following table and answer the questions given below.

Gas	% in inhaled air	% in exhaled air
Oxygen	21	16
Carbon dioxide	0.03	4.4
Nitrogen	78	78

A. Why does the amount of oxygen vary between exhaled and inhaled air?
Answer:
Gaseous exchange takes place in alveoli of lungs where oxygen is taken in, hence exhaled air contain 16% oxygen.

B. Why does exhaled air contain more carbon dioxide?
Answer:
In lungs gaseous exchange takes place in alveoli, CO₂ present in blood diffuses into alveoli. The collected CO₂ comes out as exhaled air.

C. Why there is no change in Nitrogen percentage in exhaled and inhaled air?
Answer:
Nitrogen is not present in our body. Hence there is no change in nitrogen.

V. Communication Through Drawing, Model Making

Question 1.
Draw a neat labelled diagram of power house of a cell. What is the function of inner membrane?
Answer:

Question 2.
Label the parts for given diagram.
Answer:

1. Larynx
2. Trachea
3. Right Lung
4. Brochus
5. Bronchioles

Question 3.
A student conducted an experiment in which he proved CO₂ evolved in respiration of sprouts. Draw diagram of apparatus arrangement and label parts.
Answer:

VI. Appreciation And Aesthetic Sense, Values

Question 1.
In human respiratory system different stages are there begining with nostril to gaseous exchange between blood and cell. Which of these stages do you think amazing? Why do you think so?
Answer:

• Human body consists of trillions of trillions cells, each cell in human body gets oxygen for respiration which ultimately releases energy in the form of ATR
• Most amazing thing is all the huge number of cells getting oxygen for respiration and this oxygen enter in cells through diffusion.

VII. Application to Daily life,Concern to Biodiversity

Question 1.
After learning this lesson what precautions will you lake to protect your lungs?
Answer:

• I would try to avoid most pollutant atmosphere.
• Whenever exposed to air pollutants I cover the nose and mouth with mask or cloth.
• I like to keep our surroundings parthenium’ free to avoid asthma.
• I don’t smoke and I keep away from smokers.
• I practice pranayarna to strenthen lung capacity and concentration.