NCERT Solutions for Class 7th Science
Chapter 10 – RESPIRATION IN ORGANISMS
(Complete Downloadable Chapter Solution PDF file is at the bottom of the page)
Q.1 Why does an athlete breathe faster and deeper than usual after finishing the race?
Ans During fast running, the demand for energy is high. But the supply of oxygen to produce the energy is limited. That is why an athlete breathes faster and deeper than usual after finishing the race so that more oxygen can be supplied to the body to give excess energy.
Q.2 List the similarities and differences between aerobic and anaerobic respiration.
Q.3 Why do we often sneeze when we inhale a lot of dust-laden air?
Ans When we inhale a lot of dust-laden air, the dust particles get trapped in the hair present in our nasal cavity. However, sometimes these particles may get past the hair in the nasal cavity and irritate its lining, as a result of which we sneeze. Sneezing expels these foreign particles from the inhaled air and a dust free, clean air enters our body.
Q.4 Take three test-tubes. Fill 3/4th 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?
Q.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 accumulation 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
(d) During exhalation, the ribs
(i) move outwards (ii) move downwards
(iii) move upwards (iv) do not move at all
Q.6 Match the items in Column I with those in Column II:
Column I 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
(vii) Tracheae
Ans Column I Column II
(a) Yeast (iii) Alcohol
(b) Diaphragm (iv) Chest cavity
Q.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)
Q.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
Q.9 The mountaineers carry oxygen with them because:
(a) At an altitude of more than 5 km there is no air.
(b) The amount of air available to a person is less than that available on the ground.
(c) The temperature of air is higher than that on the ground.
(d) The pressure of air is higher than that on the ground.