Question

Which of the following statement(s) is (are) true about respiration?

(i) During inhalation, ribs move inward and the diaphragm is raised.
(ii) In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air diffuses into blood and carbon dioxide from the blood into the alveolar air.
(iii) Haemoglobin has a greater affinity for carbon dioxide than oxygen.
(iv) Alveoli increase surface area for exchange of gases.

• A. (i) and (iv)
  
• B. (ii) and(iii)
  
• C. (i) and (iii)
• D. (ii) and (iv)

Answer 1

The correct option is D (ii) and (iv)

(ii) and (iv)

There are about 300 million alveoli in each of your lungs. These tiny air sacs provide an ideal site for the diffusion of gases into and out of the blood - also known as the gaseous exchange. Alveoli increase surface area for exchange of gases. The alveoli have a good air supply from the bronchioles and a rich blood supply. This is vital for successful gaseous exchange because it maintains a steep concentration gradient for oxygen from the air in the alveoli to the blood, and for carbon dioxide from the blood to the alveoli.