Rate of breathing in a newborn is about . . . . . . times per minute.

What is the last step involved in respiration?

Assertion: In mammals,a complex respiratory system has developed.
Reason: Mammalian skin is impermeable to gases.

People who have migrated from the plains to an area adjoining Rohtang Pass about six months back:

Match the following columns and select the correct option:

Column $I$	Column $II$
$(a)$ Pneumotaxic Centre	$(i)$ Alveoli
$(b)$ $O_{2}$ Dissociation curve	$(ii)$ Pons region of brain
$(c)$ Carbonic Anhydrase	$(iii)$ Haemoglobin
$(d)$ Primary site of exchange of gases	$(iv)$ $R.B.C.$

Which of the following two changes occur in humans when they move to high altitudes (above $3,500 \ m$)?
$(1)$ Increase in red blood cell size
$(2)$ Increase in red blood cell production
$(3)$ Increase in breathing rate
$(4)$ Increase in thrombocyte count