NCERT Solutions Class 7 Science
The NCERT Solutions in English Language for Class 7 Science Chapter – 10 (Respiration in Organisms) has been provided here to help the students in solving the questions from this exercise.
Chapter – 10 (Respiration in Organisms)
1. Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer – An athlete needs to supply extra energy to his muscle cells which have worked hard during running. For this, he breathes faster and deeper so that more oxygen is supplied to the cells. This speeds up the breakdown of food and as a result, more energy is released.
2. List the similarities and differences between aerobic and anaerobic respiration.
Answer –
Similarities –
- In both kinds of respiration, food particles are broken down to release energy
- Both occurs inside the cells
- Both supply by-products
Differences –
| Aerobic respiration | Anaerobic respiration |
| Takes place in the presence of Oxygen | Takes place in the absence of Oxygen |
| End products are CO2 and H2O | End products are CO2 and alcohol |
| Produces a large amount of energy | The energy released is less when compared to aerobic respiration |
| It occurs in most plants and animals | Occurs in yeast and some bacteria |
3. Why do we often sneeze when we inhale a lot of dust-laden air?
Answer – 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 foreign particles from the inhaled air and a dust-free, clean air enters our body.
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 – The is generated because of respiration by snail. Snail is an organism that breaths in and breaths out . Hence, concentration increases in test tube A.
Test tube B contains a water plant, which takes in for photosynthesis and gives out . Hence, more concentration is seen in test tube B.
Test tube C contains both snail and a water plant. The produced by the snail is utilized by the plant for photosynthesis and the released by the plant is utilized for snails respiration.
Therefore test tube A will have the highest concentration of carbon dioxide.
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
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) Trachae |
Answer –
| Column – I | Column – II |
| (a) Yeast | (iii) Alcohol |
| (b) Diaphragm | (iv) Chest cavity |
| (c) Skin | (i) Earthworm |
| (d) Leaves | (v) Stomata |
| (e) Fish | (ii) Gills |
| (f) Frog | (vi) Lungs and skin |
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)
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) The air tubes of insects – Trachea
(ii) Skeletal structures surrounding chest cavity – Ribs
(iii) Muscular floor of chest cavity – Diaphragm
(iv) Tiny pores on the surface of leaf – Stomata
(v) Small openings on the sides of the body of an insect – Spiracles
(vi) The respiratory organs of human beings – Lungs
(vii) The openings through which we inhale – Nostrils
(viii) An anaerobic organism – Yeast
(ix) An organism with tracheal system – Ant
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.
Answer – (b) The amount of air available to a person is less than that available on the ground.
