The number of $RBCs$ in man increases if he lives at a higher altitude; this is because

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

The scientist who proposed that the production of glycolic acid in guard cells is an important factor in stomatal opening is:

Mark the incorrect statement.

Select the correct option:
$(1)$ The respiratory rhythm center for breathing regulation is located in the medulla oblongata of the brain.
$(2)$ Each hemoglobin molecule can carry a maximum of $4$ molecules of $O_2$. (Note: The original question mentioned $CO_2$,which is incorrect; hemoglobin primarily transports $O_2$.)

Which two of the following changes $((i)$ to $(iv))$ usually occur in plain dwellers when they move to high altitudes ($3500 \ m$ 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