Question 1

Which of the following organisms respire through their moist skin?

Accepted Answer

Earthworms respire through their moist cuticle or skin. Oxygen dissolves in the moisture on the skin and diffuses directly into the blood capillaries, while carbon dioxide diffuses out.

Question 2

The primary site of gaseous exchange in human respiratory system is:

Accepted Answer

Alveoli are the primary sites of gaseous exchange in human lungs. They provide a very large surface area and are richly supplied with blood capillaries for efficient exchange of oxygen and carbon dioxide.

Question 3

The dome-shaped muscular structure that separates the thoracic cavity from the abdominal cavity is:

Accepted Answer

The diaphragm is a dome-shaped muscular partition that separates the thoracic cavity from the abdominal cavity and plays a major role in breathing by changing the volume of the thoracic cavity.

Question 4

During inspiration, the diaphragm:

Accepted Answer

During inspiration, the diaphragm contracts, causing it to flatten. This increases the volume of the thoracic cavity along the anteroposterior axis, reducing the pressure inside the lungs compared to atmospheric pressure.

Question 5

Total Lung Capacity (TLC) is equal to:

Accepted Answer

Total Lung Capacity (TLC) is the total volume of air accommodated in the lungs at the end of a forced inspiration. It is the sum of Vital Capacity (VC) and Residual Volume (RV), or IRV + TV + ERV + RV.

Breathing and Exchange of Gases — NCERT Class 11 Biology Important Questions & Revision Notes