Which of the following statement is /are correct about the respiratory system?
a)Breathing is an exchange of gases.
b)Diffusion of gas occurs in the lungs at the alveoli.
c)Oxygen is used by cells for anabolic reactions.
d)The diffusion membrane is made up of two major layers.
1
(a) and (b) only
2
(a) only
3
(c) and (d) only
4
(a),(b) and (d) only