NCERT Class 7 Science Chapter 10 - Respiration in Organisms

Chapter 10 - Respiration in Organisms

Question and Answers
Question 1: Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer: During the run, the demand of the energy in high but the supply of the oxygen to produce energy is limited. Therefore, anaerobic respiration takes place in the muscle cells to fulfill the demand of the energy. After finishing the race, the athlete breathes faster and deeper than usual so that more oxygen is supplied to the cells.
 
Question 2: List the similarities and differences between aerobic and anaerobic respiration.
Answer:
Similarities
1) In both aerobic and anaerobic respiration food is broken down to release energy.
2) Both takes place inside the cells.
3) Both produces byproducts.

Differences
Aerobic respiration
*It takes place in the presence of oxygen.
*Energy is released in higher amounts.
*Carbon dioxide and water are produced as byproducts.
*It is a slow process.
*Example - Plant and Animal cells

Anaerobic respiration
*It takes place in absence of oxygen.
*Energy is released in lower amounts.
*Carbon dioxide and alcohol are produced.
*It is a fast process.
*Example - Human cells, yeast, bacteria etc
 
Question 3: Why do we often sneeze when we inhale a lot of dust - laden air?
Answer: We often sneeze when we inhale a lot of dust -laden air to expel out these foreign particles. These particles get pass the hair in the nasal cavity and irritate the lining of the cavity which results sneezing.
 
Question 4: Take three test tubes. Fill each of them 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, snail and plant both. Which test tube would have the highest concentration of Carbon dioxide?
Answer: Test tube A will have the highest concentration of Carbon dioxide.
In test tube tube B and C, the carbon dioxide will be utilised by the water plant for synthesizing food and hence there will be less concentration of carbon dioxide in these.
 
Question 5: Fill in the blanks
a) In cockroaches, air enters the body through spiracles.
b) During heavy exercise, we get cramps in legs due to accumulation of lactic acid.
c) Normal range of breathing rate per minute in an average adult person at rest is 15 - 18.
d) During exhalation, the ribs move downwards.
 
Question 6: Mark 'T' if the statement is true and 'F' if the statement is false.
a) During heavy exercise the breathing rate of a person slows down. (False)
b) Plants carry out photosynthesis only during day and respire only at night. (False)
c) Frogs breathe through their skin as well as their lungs. (True)
d) The fish have lungs for their respiration. (False)
e) The size of the chest cavity increases during inhalation. (True)