Question

It has been found that people living in very high mountains have many more red corpuscles in their blood than people living in plains. Which one of the following best accounts for this phenomenon?

Options

• the cold climate stimulates the production of red corpuscles to keep the body warm

• people of high mountains breathe more quickly

• the low air pressure requires more red corpuscles to supply the body cells with oxygen

• the low air pressure in high mountains speeds up the blood circulation so that more red corpuscles are needed

Answer 1

the low air pressure requires more red corpuscles to supply the body cells with oxygen

Explanation:

At high altitudes, the atmospheric oxygen pressure is low. As a result, less oxygen is available for the body. Therefore, the body produces more red blood cells (red corpuscles) to transport sufficient oxygen to the body cells. Hence, people living in very high mountains have more red corpuscles in their blood than those living in the plains.