NCERT Grade 7 Science, Chapter 6, Respiration in Organisms is all about respiration, the reasons behind respiration, and a few different concepts related to respiration. The first component discusses the motives at the back of breathing. Under this, terms like cell respiration along with the site of cell respiration are defined.
The procedure of breakdown of food with and without the presence of oxygen is explained using chemical equations. The procedure of anaerobic respiration is explained under situations like a breakdown of meals and muscles. The breathing mechanism along with the procedure of inhalation and exhalation is defined in the chapter, Respiration in Organisms. The activity enables us to recognize the changes in breathing rate under one-of-a-kind conditions.
Thereafter, the mechanism of breathing in human beings is significantly defined using diagrams in the chapter, Respiration in Organisms. Focus is likewise given to parts like the nasal cavity, lungs, chest cavity, and diaphragm. The harmful consequences of smoking are mentioned in short. Under the human respiration system, the impact of respiratory at the chest length has defined the usage of pastime and a model showing it diagrammatically. The idea of breathing in animals is mentioned via means of taking examples of cockroaches and earthworms. The procedure of breathing underwater is defined along with a figure depicting the different breathing organs of fish. At last respiration in the case of plants is covered in the chapter, Respiration in Organisms.
Class 7 Science NCERT Solutions for Chapter 5 – Physical and Chemical Changes
1. Why does an athlete breathe faster and deeper than usual after finishing the race?
Solution:
Athletes need a lot of energy during the race, and for the release of energy, they need a lot of oxygen; hence they breathe faster than usual after finishing the race.
2. List the similarities and differences between aerobic and anaerobic respiration.
Solution:
Similarities:
- In both kinds of respiration, food particles are broken down to release energy
- Both occur inside the cells
- Both supply by-products
Differences
| Aerobic respiration | Anaerobic respiration |
| Takes place in the presence of oxygen | It occurs in yeast and some bacteria |
| It takes place in the absence of oxygen | The end products are CO2 and H2O |
| Produces a large amount of energy | The energy released is less when compared to aerobic respiration |
| It occurs in most plants and animals | It takes place in the presence of oxygen |
3. Why do we often sneeze when we inhale a lot of dust-laden air?
Solution:
When we inhale dust-laden air, the dust irritates the nose; as a reflexive action, dust is thrown out through sneezing.
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 both the snail and plant. Which test tube would have the highest concentration of CO2?
Solution:
Test tube A will have the highest concentration of CO2 because test tube A has a snail which expels out CO2 into the tube. Since a plant is present in both test tubes B and C, the plant will inhale CO2 to decrease CO2 concentration. Thus, there will be less concentration of CO2 in these tubes.
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) The 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
Solution:
a) (iii) spiracles
b) (ii) lactic acid
c) (ii) 15–18
d) (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) Trachea |
Solution:
| 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) Fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)
Solution:
i) False
ii) False
iii) True
iv) False
v) True
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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 the chest cavity
(iii) Muscular floor of the chest cavity
(iv) Tiny pores on the surface of a 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 a tracheal system
Solution:
(i) Trachea
(ii) Ribs
(iii) Diaphragm
(iv) Stomata
(v) Spiracles
(vi) Lungs
(vii) Nostrils
(viii) Yeast
(ix) 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.
Solution:
The answer is (b). The amount of air available to a person is less than that available on the ground.