# NCERT Solutions for Class 11 Biology Chapter 17

## Breathing and Exchange of Gases Class 11

### Exercise : Solutions of Questions on Page Number : 277

Q1 :

Define vital capacity. What is its significance?

Vital capacity is the maximum volume of air that can be exhaled after a maximum inspiration. It is about 3.5 - 4.5 litres in the human body. It promotes the act of supplying fresh air and getting rid of foul air, thereby increasing the gaseous exchange between the tissues and the environment.

Q2 :

State the volume of air remaining in the lungs after a normal breathing.

The volume of air remaining in the lungs after a normal expiration is known as functional residual capacity (FRC). It includes expiratory reserve volume (ERV) and residual volume (RV). ERV is the maximum volume of air that can be exhaled after a normal expiration. It is about 1000 mL to 1500 mL. RV is the volume of air remaining in the lungs after maximum expiration. It is about 1100 mL to 1500 mL.

∴FRC = ERV + RV

≅ 1500 + 1500

≅ 3000 mL

Functional residual capacity of the human lungs is about 2500 - 3000 mL.

Q3 :

Diffusion of gases occurs in the alveolar region only and not in the other parts of respiratory system. Why?

Q4 :

What are the major transport mechanisms for CO2? Explain.

Q5 :

What will be the pO2 and pCO2 in the atmospheric air compared to those in the alveolar air?

(i) pO2 lesser, pCO2 higher

(ii) pO2 higher, pCO2 lesser

(iii) pO2 higher, pCO2 higher

(iv) pO2 lesser, pCO2 lesser

Q6 :

Explain the process of inspiration under normal conditions.

Q7 :

How is respiration regulated?

Q8 :

What is the effect of pCO2 on oxygen transport?

Q9 :

What happens to the respiratory process in a man going up a hill?

Q10 :

What is the site of gaseous exchange in an insect?

Q11 :

Define oxygen dissociation curve. Can you suggest any reason for its sigmoidal pattern?

Q12 :

Q13 :

Distinguish between

(a) IRV and ERV

(b) Inspiratory capacity and Expiratory capacity

(c) Vital capacity and Total lung capacity