Thermo-regulation in dogs takes place by

Whales are air-breathers but can live underwater for a long time because they possess:

At sea level,the blood of individuals contains approximately $5$ million red blood cells per cubic millimeter. However,individuals living at an altitude of $5400$ meters have $8$ million red blood cells per cubic millimeter. Why does this increase occur?

Which two of the following changes $(i-iv)$ usually tend to occur in plain dwellers when they move to high altitudes ($3,500 \ m$ or more)?
$(i)$ Increase in red blood cell size
$(ii)$ Increase in red blood cell production
$(iii)$ Increased breathing rate
$(iv)$ Increase in thrombocyte count
Changes occurring are

Which of the following is a plant showing scotoactive opening of stomata?

Which of the following is a respiratory gas?