Which of the following is a respiratory gas?

At high altitudes,the number of red blood cells in humans:

Which of the following is not the function of the conducting part of the respiratory system?

People who have migrated from the plains to an area near Rohtang Pass six months ago will exhibit which of the following characteristics?

What is the respiratory rate in a rabbit?

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 $O_2$.)