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DAV Class 7 Science Book Solution Chapter 7

DAV Class 7 Science Book Solution Chapter 7: Here is the complete solution for DAV Class 7 Science Book Chapter 7 Respiration in Organisms. Those students who are interested please check it out.

DAV Class 7 Science Book Solution Chapter 7


A. Fill in the blanks.

1. Lactic acid is produced during ___________ respiration.

2. Insects have organs, called ___________, for respiration.

3. Taking in of air, rich in oxygen, is called ___________.

4. An adult human being normally breathes from ___________ to ___________ times per minute.

5. The movement of lungs is controlled by the ___________ and the ___________.

6. ___________ acts as the respiratory carrier in our body.

Answer: (1) anaerobic (2) tracheae (3) inhalation (4) 14, 20 (5) diaphragm, ribcage (6) Haemoglobin

B. Match the following:

1. Lactic acid                            (a) Transpiration

2. Stomata                               (b) Pores on branches

3. Respiratory carrier             (c) Muscle cramps

4. Lenticels                              (d) Fermentation of yeast

5. Alcohol                                (e) Haemoglobin

Answer: 1. (c), 2. (a), 3. (e), 4. (b), 5. (d)

C. Tick the correct option.


1. obtaining energy

2. exchange of gases

3. is aerobic respiration

4. oxygen

5. skin

D. Answer the following questions in brief.

Q. 1. Define respiration. Name the two types of respiration.

Answer: The process in which living organisms convert sugars into biological energy using oxygen is called respiration. 

Two types of respiration are –

(1) Aerobic respiration

(2) Anaerobic respiration

Q. 2. Name the respiratory organ of the following:

(a) crab (b) man (c) leech (d) an insect


(a) Gills

(b) Lungs

(c) Skin

(d) Tracheae

Q. 3. Define transpiration.

Answer: Loss of excess water from plants through open stomata is called transpiration

Q. 4. Define the term ‘breathing rate’.

Answer: The number of times an animal breathes per minute is called its breathing rate.

Q. 5. Name the body organs which help lungs during the process of breathing.

Answer: Ribcage and diaphragm.

Q. 6. Why do we need to breathe out carbon dioxide?

Answer: High levels of carbon dioxide in the body can be toxic and hence, carbon dioxide needs to be removed.

E. Answer the following questions.

Q. 1. Why do we get muscle cramps after heavy exercise?

DAV Class 7 Science Book Solutions Chapter 7

Q. 2. Why does a potted plant die when over watered?


A potted plant die when over watered because the cells, in the roots of the plants, also need oxygen to survive. They take in air from the air spaces present between the soil particles. When over watered, the air spaces, in the soil, get occupied by water and this prevents the plants roots from taking in air that they need. Therefore, a potted plant dies if over-watered.

Q. 3. Where are stomata found in a plant? State their function.

Answer: Stomata are fond on the surface of leaves of a plant.

Functions of stomata – 

(1) Help in exchange of gases (oxygen and carbon dioxide). 

(2) Lose excess amount of water in the form of water vapour.

Q. 4. How is oxygen transported from lungs to the other parts of the body?


Oxygen is transported from lungs to the other parts of the body with the help of haemoglobin. The blood, while passing through the lungs, picks up oxygen with the help of haemoglobin which transports oxygen to different parts of the body.

Q. 5. Draw a neat, well-labelled diagram of the human respiratory system.

Answer: For diagram see page no. 108 of your book.

Q. 6. Describe an activity to show that exhaled air contains carbon dioxide.

DAV Class 7 Science Book Solution Chapter 7

Q. 7. Describe the changes that take place (i) around the rib cage (ii) diaphragm (iii) chest cavity, during inspiration. State the effect of these changes.


(1) During inspiration, the muscles, around the rib cage, contract, lifting the ribs upward and outward 

(2) Diaphragm contracts and becomes nearly flat sheet. 

(3) The chest cavity expands.

Effect – Air pressure inside the lungs falls below the pressure of the air outside the body. This creates a partial vacuum and so the air. from outside the body, rushes into the lungs.

20 thoughts on “DAV Class 7 Science Book Solution Chapter 7”

  1. Great website
    I can see there was hardwork in it
    Sorry for the earlier dum comments
    But this actually helped me
    Thanks and continue with the hardwork


  2. Tum dhund let ho na or agar dhund lete ho toh is website kyu check kiya, dumb aadmi .pehle khud krne se se phele apne ko dekho.

    Mind your own business.

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