Class 7 Science Chapter 10 Respiration in Organisms

Class 7 Science Chapter 10 Respiration in Organisms

Class 7 Science Chapter 10 Respiration in Organisms for CBSE/ICSE  Students.


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

Ans:-When an athlete runs hard, his muscles require extra energy. For this reason, he breathes faster and deeper, which allows more oxygen into his cells. As a result, food breaks down faster, releasing more energy.


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


During anaerobic and aerobic respiration, food is broken down to release energy.

Aerobic respiration Anaerobic respiration
In the presence of oxygen, aerobic respiration occurs Anaerobic respiration occurs in the absence of oxygen
CO2 and H2O are its end products. lactic acid, CO2, and alcohol as end products.
Most organisms respire aerobically. usually happens in most of the microbes
Complete breakdown of food occurs Partial breakdown of food occurs
produces a considerable amount of energy produces less energy

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

Ans:-Sneezing eliminates foreign materials from the air we inhale, allowing us to breathe clean air into our bodies. It usually occurs due to irritation of the upper respiratory passage. When we inhale a lot of airborne particles and they get trapped in our nasal cavity, we get irritated. Smoke, dust and other unwanted particles can cause sneezing.


QUE.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 testtube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?

Ans:-The highest concentration of CO2 will be found in test tube A. Due to the snail in test tube A. The snail breathes in O2 and exhales CO2. As a result, CO2 concentration increases in test tube A.

An oxygen-producing plant is in test tube B, which uses CO2 to produce food. In test tube B, there is a higher concentration of O2.

Both snails and plants can be found in test tube C. The snail produces CO2 which is utilized by the plant for food synthesis and the plant releases oxygen which is utilized by the snail for respiration.

Thus, test tube A has the highest concentration of CO2.


QUE.5 :Tick the correct answer:

(a) In cockroaches, air enters the body through

(i) lungs

(ii) gills

(iii) spiracles [Correct Answer]

(iv) skin


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

(i) carbon dioxide

(ii) lactic acid [Correct Answer]

(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 [Correct Answer]

(iii) 21-24

(iv) 30-33

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