Question

People living at sea level have around 5 million RBC per cubic millimetre of their blood whereas, those living at an altitude of 5400 metres have around 8 million. This is because at high altitude:

• A. people eat more nutritive food so more RBCs are formed
• B. people get pollution-free air to breathe and more oxygen is available
• C. atmospheric oxygen level is less and hence, more RBCs are needed to absorb the required amount of oxygen to survive
• D. there is more UV radiation which enhances RBC production

Answer 1

Answer: (C)

atmospheric oxygen level is less and hence, more RBCs are needed to absorb the required amount of oxygen to survive

The number of RBCs per cubic millimetre of blood is likely to be higher in people living at high altitudes. This is in response to the air being less dense at high altitudes. Thus, more RBCs (haemoglobin) are needed to absorb the required amount of $O_2$ from the air.