Class 11 NEET Biology Breathing and Exchange of Gases

Here's the reasoning behind this order:(D) Pulmonary ventilation by which atmospheric air is drawn in and $\mathrm{CO}_2$ rich alveolar air is released out.Respiration begins with pulmonary ventilation (breathing), which allows the atmospheric air to enter the lungs and $\mathrm{CO}_2$-rich air to be exhaled.(A) Diffusion of gases $\left( \mathrm{O}_2.\mathrm{CO}_2\right)$ and $\left( \mathrm{O}_2.\mathrm{CO}_2\right)$ across the alveolar membrane.Inside the lungs, oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli across the alveolar membrane.(C) Transport of gases by the blood.Once in the bloodstream, oxygen and carbon dioxide are transported to and from the body's tissues.(B) Diffusion of $\mathrm{O}_2$ and $\mathrm{CO}_2$ between blood and tissues.Oxygen diffuses from the blood into the body's tissues, and carbon dioxide diffuses from the tissues into the blood.(E) Utilisation of $\mathrm{O}_2$ by the cells for catabolic reactions and resultant release of $\mathrm{CO}_2$. Finally, oxygen is used by cells for metabolic processes, creating carbon dioxide as a byproduct.