Question

Which two of the following changes (i - iv) usually tend to occur in the plain dwellers when they move to high altitudes (3,500 m or more)?
(i) Increase in red blood cell size
(ii) Increase in red blood cell production
(iii) Increase breathing rate
(iv) Increase in thrombocyte count.
Changes occurring are

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

Answer 1

The correct option is A (ii) and (iii)

Breathing rate and depth increase in response to lower concentrations of oxygen in the blood, causing more carbon dioxide to be lost and more oxygen to be delivered to the alveoli. As acclimatisation continues, the bone marrow contributes by increasing red blood cell production. New red blood cells become available in the blood within four to five days, increasing the blood's oxygen-carrying capacity.