NCERT Solutions for Class 7 Science Chapter 10 Respiration in Organisms

Exercises

Question:- 1. Why does an athlete breathe faster and deeper than usual after finishing the race?

Answer:- Athletes use a lot of energy during the race, and they require a lot of oxygen to release that energy; as a result, they breathe faster than usual after the race.

Question:- 2. List the similarities and differences between aerobic and anaerobic respiration.

Answer:- Similarities:

1. Food particles are broken down to release energy in both types of respiration. Both take place inside the cells.
2. Both provide by-products.

Differences:-

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

Answer:- When we inhale dust-laden air, it irritates our nose; as a reflexive action, we sneeze to expel the dust.

Question:- 4. Take three test-tubes. Fill ¾th 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 ?

Answer:- Because test tube A contains Snail, which exhale CO2 into the tube, it will have the greatest CO2 concentration. Because a plant is present in both test tubes B and C, it will inhale CO2 to lower CO2 levels. As a result, the CO2 content in these tubes will be lower.

Question:- 5. Tick the correct answer:

(a) In cockroaches, air enters the body through

(i) lungs                              (ii) gills

(iii) spiracles                      (iv) skin

Answer:- (iii) spiracles                      

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

(i) carbon dioxide                         (ii) lactic acid

(iii) alcohol                                    (iv) water

Answer:- (ii) lactic acid

 (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

Answer:- (ii) 15–18

 (d) During exhalation, the ribs

(i) move outwards                (ii) move downwards

(iii) move upwards               (iv) do not move at all

Answer:- (ii) move downwards

Question:- 6. Match the items in Column I with those in Column II:

Answer:-

Question:- 7. 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)

Answer:- (i) During heavy exercise the breathing rate of a person slows down. ( False )

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

(iii) Frogs breathe through their skins as well as their lungs. (True )

(iv) The fishes have lungs for respiration. ( False )

(v) The size of the chest cavity increases during inhalation. (True)

Question:- 8. Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction — upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

 (i) The air tubes of insects

(ii) Skeletal structures surrounding chest cavity

(iii) Muscular floor of chest cavity

(iv) Tiny pores on the surface of leaf

(v) Small openings on the sides of the body of an insect

(vi) The respiratory organs of human beings

(vii) The openings through which we inhale

(viii) An anaerobic organism

(ix) An organism with tracheal system

Answer:- (i) Trachea

(ii) Ribs

(iii) Diaphragm

(iv) Stomata

(v) Spiracles

(vi) Lungs

(vii) Nostrils

(viii) Yeast

(ix) Ant