Study Materials

NCERT Solutions for Class 7th Science


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Chapter 10. Respiration in Organisms

NCERT Exercise





Q1. Why does an athlete breathe faster and deeper than usual after finishing the race?


During running, the athlete uses up lot of energy. So, he/she needs more energy and so breathes faster breakdown of food to release energy.

Q2. List the similarities and differences between aerobic and anaerobic respiration.


Similarity: (i) Energy is released.

(ii)Carbon dioxide is produced.

Differences: (i) Anaerbic respiration does not reqire oxygen while aerobic respiration take place in the presence of oxygen.

(ii) Glucose is completly broken down into carbon dioxide and water in aerobic respiration but not in anaerobic respiraton.

3. Why do we often sneeze when we inhale a lot of dust-laden air?


When we inhale a lot of dust laden air often these particles get trapped in the hair present in the nasal cavity. then they irritate the lining of the cavity,as a result  of which we sneeze. Sneezing expels these foregion particles from the inhaled air and a dust free, clean air enters our body. 

4. Take three test-tubes.Fill th of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?


Test - Tube - C.

5. Tick the correct answer:

(a) In cockroaches, air enters the body through

(i) lungs (ii) gills (iii) spiracles (iv) skin

(b) During heavy exercise, we get cramps in the legs due to the accu mulation of

(i) carbon dioxide (ii) lactic acid (iii) alcohol (iv) water

(c) Normal range of breathing rate per minute in an average adult person at rest is:

(i) 9–12 (ii) 15–18 (iii) 21–24 (iv) 30–33


(a) - (iii)

(b) - (ii)

(c) -(ii) 

(d) - (ii)

Column I Column II6. Match the items in Column I with those in Column II:

(a) Yeast (i) Earthworm

(b) Diaphragm (ii) Gills

(c) Skin (iii) Alcohol

(d) Leaves (iv) Chest cavity

(e) Fish (v) Stomata

(f) Frog (vi) Lungs and skin 


Column I Column II
(a) Yeast (iii) Alcohol
(b) Diaphagram (iv)Chest cavity
(c) Skin (i) earthworm
(d) Leaves (v) Stomata
(e) Fish (ii) Gills
(f) Frog (vi) Lungs and skin

Q7. Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) During heavy exercise the breathing rate of a person slows down. (T/F)

(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)

(iii) Frogs breathe through their skins as well as their lungs. (T/F)

(iv) The fishes have lungs for respiration. (T/F)

(v) The size of the chest cavity increases during inhalation. (T/F)

air is higher than that on the ground. (T/F)


(i) false

(ii) false

(iii) true

(iv) false

(v) true


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