At night, when photosynthesis is not occurring, carbon dioxide elimination is the major exchange activity. During the day, carbon dioxide generated during respiration is used up for photosynthesis, resulting in oxygen release as the major gas exchange activity.

Plants exchange gases through stomata, and diffusion occurs in the large inter-cellular spaces. Carbon dioxide and oxygen are exchanged based on environmental conditions and the needs of the plant.

Aerobic organisms depend on oxygen for aerobic respiration, which is essential for producing ATP and meeting the energy demands of the cell.

ATP is broken down, releasing a fixed amount of energy that can drive endothermic reactions within the cell.

The primary molecule synthesized during cellular respiration is ATP (adenosine triphosphate), which serves as the primary energy currency of the cell, fueling various cellular activities.