Select the sequence of steps in Respiration. (A) Diffusion of gases $\left(\mathrm{O}_2\right.$ and $\left…
Select the sequence of steps in Respiration.
(A) Diffusion of gases $\left(\mathrm{O}_2\right.$ and $\left.\mathrm{CO}_2\right)$ across alveolar membrane.
(B) Diffusion of $\mathrm{O}_2$ and $\mathrm{CO}_2$ between blood and tissues.
(C) Transport of gases by the blood.
(D) Pulmonary ventilation by which atmospheric air is drawn in and $\mathrm{CO}_2$ rich alveolar air is released out.
(E) Utilisation of $\mathrm{O}_2$ by the cells for catabolic reactions and resultant release of $\mathrm{CO}_2$.
Choose the correct answer from the options given below :
(B), (C), (E), (D), (A)
(A), (C), (B), (E), (D)
(D), (A), (C), (B), (E)
(C), (B), (A), (E), (D)
Solution
Option (3) is the answer, because the respiration involves the following stages:
1. Breathing or pulmonary ventilation by which atmospheric air is drawn in and $\mathrm{CO}_2$ rich alveolar air is released out.
2. Diffusion of gases $\left(\mathrm{O}_2\right.$ and $\left.\mathrm{CO}_2\right)$ across alveolar membrane.
3. Transport of gases by the blood.
4. Diffusion of $\mathrm{O}_2$ and $\mathrm{CO}_2$ between blood and tissue.
5. Utilisation of $\mathrm{O}_2$ by the cells for catabolic reactions and resultant release of $\mathrm{CO}_2$
Rest of options (1), (2) and (4) are not the answers because these steps are not arranged in the correct sequence.