Why do tribes who live in high altitude of Himalayas experience discomfort in respiration? How do they get adapted to survive in such a situation?

Many tribes living in high altitudes of Himalayas have :

Why do ink pens start leaking at high altitudes?

Many tribes living in high altitudes of Himalayas have higher red blood cell count. Do you agree?

How do sea animals adapt themselves to live in seas?

Assertion: Many tribes live in the high altitude of Himalayans have a higher red blood cell count or total hemoglobin than people living in the plains. Reason: At high altitude, body does not get enough oxygen.

Many tribes living in high altitude of Himalayas normally have higher red blood cell count (or) total haemoglobin than the people living in the plains. Explain ?

Unlike mammals the reptiles cannot tolerate environmental fluctuations in temperature. How do they adapt to survive in desert conditions ?

How do you infer the presence of CO_2 in respiration experiments ?