Adaptation : It is any attribute of an organism, i,e., morphological, physiological or behavioural that enables the organism to survive and reproduce in its habitat.

At high altitude places like Rohtang Pass near Manali (> 3500 m) and Mansarovar, in China occupied Tibet, people suffer from Altitude sickness. This is because of low atmospheric pressure at high altitude, body does not get enough oxygen. Its symptoms are nausea, fatigue and heart palpitations. The relief occurs gradually due to acclimatisation. The body cope up with this low oxygen stress by increasing red blood cells production, decreasing the binding affinity of haemoglobin and increasing the breathing rate.