Human body compensates low oxygen availability at high altitudes by:
(A) increasing number of red blood cells
(B) decreasing the binding affinity of haemoglobin
(C) increasing the binding affinity of haemoglobin
(D) increasing breathing rate
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B) and (D) only
(A) increasing number of red blood cells — True.
(B) decreasing the binding affinity of haemoglobin — True. Oxygen is released more readily to the tissues.
(C) increasing the binding affinity of haemoglobin — False. The binding affinity decreases.
(D) increasing breathing rate — True.
Note: This question is from the topic “Adaptations” in Chapter 13, Organisms and Populations, of the pre-rationalised NCERT book. This portion is not in the present NCERT book, where the chapter is now Chapter 11, Organisms and Populations. The extract below is from the pre-rationalised edition.
NCERT Extract (Pre-rationalised edition, Chapter 13, Organisms and Populations):
Adaptations – “… If you had ever been to any high altitude place (>3,500m Rohtang Pass near Manali and Leh you must have experienced what is called altitude sickness. Its symptoms include nausea, fatigue and heart palpitations. This is because in the low atmospheric pressure of high altitudes, the body does not get enough oxygen. But, gradually you get acclimatised and stop experiencing altitude sickness. … The body compensates low oxygen availability by increasing red blood cell production, decreasing the binding affinity of hemoglobin and by increasing breathing rate.”