NCERT Exemplar Problem Class 7 Science Respiration in Organisms

Here in this post we provided NCERT Exemplar Problem Class 7 Science Respiration in Organisms Chapter 10 Full Explanation by group of Science Experts. We have provided here each questions answer with reason behind the answer.

Hope it help you!

Respiration in Organisms Class 7 Exemplar full Explanation:

1) Sometimes we do heavy exercises, anaerobic respiration takes place in our muscle cells. What is produced during this process?

a) Alcohol and lactic acid

b) Alcohol and CO2

c) Lactic acid and CO2

d) Lactic acid only

Answer:- d) Lactic acid only

Lactic acid is produced during the anaerobic respiration in our muscle cells.

3) During the process of exhalation, the ribs move

a) Down and inwards.

b) Up and inwards.

c) Down and outwards.

d) Up and outwards.

Answer:-a) Down and inwards

During the process of exhalation, the ribs move Down and inwards.

4) Breathing is a process that

a) Provides O2 to the body.

b) Breaks down food to release energy.

c) Helps the body to get rid of CO2

d) Produces water in the cells.

Which of the following gives the correct combination of functions of breathing?

a) I and II

b) II and III

c) I and III

d) II and IV

Answer:- c) I and III

Breathing is a process provides O2 to the body and helps the body to get rid of CO2.

5) Fish breaths with the help of gills which are richly supplied with blood vessels. The gills help the fish to

a) Take in oxygen from air.

b) Take in oxygen dissolved in water .

c) Absorb nutrients present in water.

d) Release waste substances in water.

Answer:- b) Take in oxygen dissolved in water.

Gills help the fishes to breathe the oxygen which is dissolved in water.

6) Earthworms and frogs breaths through their skin because of which the skin of both the organisms is

a) Moist and rough.

b) Dry and rough.

c) Dry and slimy.

d) Moist and slimy.

Answer:-d) Moist and slimy.

Earthworms and frogs breaths through their skin because of which the skin of both the organisms moist and slimy.

  • Very Short Answer Questions

7) Mark the following statements as true or false. Correct the false statements.

A) Oxygen breaks down glucose outside the cells of organisms.

Answer:- False

The breakdown of glucose due to oxygen occurs inside the cells of organisms.

B) Frogs can breath through their skin as well as lungs.

Answer:- True.

C) Insects have spiracles on the lower surface of the body.

Answer:- False.

They have spiracles on the sides of body.

D) Exhaled air has more percentage of CO2 than inhaled air.

Answer:- True.

8) Fill in the blanks with suitable words.

a) The roots of a plant take up oxygen from the _____________ trapped between the ___________ particles.

Answer:-  the roots of a plant take up oxygen from the air Trapped between the soil particles.

b) Diaphragm forms the ___________ of the chest cavity.

Answer:- Diaphragm forms the floor of the chest cavity.

c) Exchange of Gases in the leaves take place with the help of ___________.

Answer:- Exchange of gases in the leaves take place with the help of stomata.

d) Cockroaches breaths with the help of air tubes called ___________.

Answer:- cockroaches breaths with the help of air tubes called tracheae.

  • Short Answer Questions

9) Pick the odd-one-out from each of the groups given below on the basis of respiratory organs. Give reason for your answer.

a) Cockroach, grasshopper, snail, ant

Odd word :- snail

Snails does not breath by the trachea.

b) Lizard, cow, earthworm, snake

Odd word:- Earthworm

Earthworms breath by the skin they don’t have lungs.

c) Crocodile, whale, dolphin, fish

Odd word:-  Fish

Fishes breathe with their skin they don’t have lungs.

d) Snake, tadpole, crow, goat

Odd word:- Tadpole

As it breathes through gills and does not have lungs.

10) Which gas present in air is essential for aerobic respiration? What is the role of oxygen during respiration?

Answer:- oxygen present in air is essential for the aerobic respiration. Living organisms respire for the energy. When we breathe we take oxygen from the air, and we breathe out the carbon dioxide. The oxygen we breathe is transferred to the each an every cell of the body. After that with the help of oxygen breakdown of food occurs which release the energy. This process in the cell in which breakdown of food with the release of energy is known as cellular respiration. In the cells of all the organisms cellular respiration takes place. This is the role of oxygen during respiration.

11) On an average, an adult human being at rest breaths 15-18 times per minute. The breathing rate, however may differ under different conditions. Arrange the following activities given in the box in order of increasing breathing rates and give reason for your answer.

Sleeping, cycling, brisk walk, watching T.V.


Sleeping→ watching T.V → brisk walk → cycling

When there is any physical activity, the breathing rate increases. When a work is more strenuous then the breathing becomes faster. As work with more strength needs more energy thus it needs more oxygen for that the breathing rate increases. In above order the given works are in increasing order sleeping need less energy, further it goes increasing to the cycling as it needs much more energy.

12) On a very cold morning, boojho and paheli were talking with each other as they walked down to their school. They observed that the air coming out of their mouth looked like smoke. They were amused and wondered how it happened. Help them find the answer.

Answer:- On a very cold morning, there is low temperature outside but our body maintain the body temperature. During the exhalation process our body excels moist and warm air which condenses into mist when these air comes in contact with the cold air of surrounding outside. Therefore the air expelled by us looks like white smoke.

13) Whenever we feel drowsy or sleepy, we start yawning. Does yawning help us in anyway?

Answer:- When we sleep there is no physical activity thus our breathing rate gets very low. Sleepiness or drowsy feeling leads to yawning. Whenever we feel drowsy our breathing rate decreases. Thus the lungs do not get enough oxygen by the process of breathing. As a result of it we feel yawning. Yawning keeps us awake and brings more enough oxygen to the lungs.

14)  Insects and leaves of a plant have pores through which they exchange gases with the atmosphere. Can you write two points of differences between these pores with respect to their position, number and extension into the body.


Insects have small opening on the sides of the body which is called as spiracles. And the leaves have small opening which is called stomata is present On the Lower surface of leaves.

Spiracles in the insects are very less in number as compared to stomata on the leaves.

Spiracles are used for the tracheal network system for the respiration, but these is absent in leaves.

Stomata is useful for the gases exchange or removal of waste of leaves which is not done by the spiracles.

Long Answer Questions

15) Paheli participated in a 400 m race competition held at her school and won the race. When she came home she had mixed feelings of joy and pain as she had cramps in her leg muscles. After a massage she was relieved of the pain. Answer the following questions to the situation.

a) What can be the possible reasons for the pain in her legs?

Answer:- When there is heavy exercise or running etc then the muscles cells respire anaerobically. During anaerobic respiration in the muscles cells lactic acid is produced. Due to the accumulation of the lactic acid in the muscles of her legs the pain could be occur.

b) Why did she feel comfortable after a massage?

Answer:- Due to running or heavy exercise the muscles cells respire anaerobically producing lactic acid. Because of the accumulation of lactic acid in the muscles her legs were paining. But when she take a massage she felt comfortable. Massage improves the blood circulation. Blood circulation increases the supply of oxygen. Because of increased oxygen there is complete breakdown of lactic acid accumulated in the muscles, and thus she feel comfortable after this.

16) Observe figure 10.1 carefully and answer the following questions.

a) In which jar, will the amount of CO2 be the Highest and why?

Answer:-In the jar C the amount of CO2 will be highest because the mice kept under the jar continuously breathe out the CO2, which increases the amount of CO2 in the bell jar.

b) In Which jar, will the amount of CO2 be the lowest and why?

Answer:- In the jar A the amount of CO2 will be low as compared to the other jar. The CO2  released during the respiration is used by the plants when the process of photosynthesis occur by the plants. Therefore in jar A there will be less CO2.

17) Observe figure 10.2 carefully and answer the following questions.

a) Which processes is being tested in the activity?

Answer:- In the given figure, the process of Exhalation during the respiration is being tested in the activity.

b) What is the result of the activity? Give reasons.

Answer:- in the given figures the activity of the Exhalation during respiration is tested. In which test tube A has water in it and test tube B has lime water.

When the CO2 released by the respiration reacts with lime water in test tube B, it turns milky. But in test tube A there is no change.

18) A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to the dough and left it in a warm place. After few hours, the dough had risen. There was a sour smell too.

a) Why did the dough rise ?

Answer:-  The prepared dough of bhaturascontains yeast and sugar, and it left in the warm place. During the respiration by the yeast the release of CO2 takes place which rises the dough.

c) Why was sugar added to the dough?

Answer:- Dough contains yeast which respire anaerobically. Sugar added in the dough act as a food of the yeast .

d) What would have happened if the dough was kept in the refrigerator, soon after it was prepared?

Answer:-  yeast is added to the dough so that the dough should rise and becomes sour and fluffy. In the refrigerator there will be low temperature in which the yeast could not multiply and respire and it will not lead to the rise in the dough or become sour.

19) Observe the figure given as figure 10.3 (A) and (B) and answer the following.

A) Which of the following A or B indicates the process of inhalation and which the process of exhalation?

Answer:- figure A indicates the process of Inhalation.

As the diaphragm moving down in figure A indicates Inhalation.

Figure B shows the Exhalation process.

Ribs are moving back and upward.

B) In the figure label the arrows and indicate the direction of

I) Movement of air

II) Movement of diaphragm

III) Movement of ribs


(20) Match the names of organisms in column I with their organs of breathing given in column II.

Column I Column II
a)           Butterfly i)                           Lungs
b)           Earthworms ii)                       Gills
c)             Sparrow iii)                   Spiracles
d)           Fish iv)                    Skin

A) Butterfly → iii) spiracles
B) Earthworms → iv) skin
C) Sparrow → i) Lungs
D) Fish → ii) Gills

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