PART - 2 - Unit V : CH - 14 Breathing and Exchange of Gases — BIOLOGY STD 11 Science — Question

Respiration : This process of exchange of atmospheric O₂ and CO₂ produced in cells is called breathing or respiration.
The stages of respiration are as follows:
(1) Respiration or pulmonary breathing by which atmospheric air is drawn in and alveolar air rich in CO₂ is released outside.
(2) Diffusion of gases (O₂ and CO₂) across the alveolar membrane.
(3) Transport of gases by blood.
(4) Diffusion of O₂ and CO₂ between blood and tissues.
(5) Use of O₂ by the cells for catabolic reactions and as a result generation of CO₂.