Occurs in cells containing chloroplasts. Uses carbon dioxide. Occurs in sunlight. By now, it should be clear that respiration is the reverse of photosynthesis. Unlike photosynthesis, respiration occurs at night as well as during the day.
Respiration occurs in all life forms and in all cells.
The release of accumulated carbon dioxide and the uptake of oxygen occurs at the cell level. In animals, blood carries both oxygen and carbon dioxide to and from the atmosphere by means of the lungs, gills, spiracles etc. In plants there is simple diffusion into the open spaces within the leaf and exchange occurs through the stomata. Transpiration is necessary for mineral transport from the soil to the plant for the cooling of the plant through evaporation, to move sugars and plant chemicals, and for the maintenance of turgor pressure. The amount of water lost from the plant depends on several environmental factors such as temperature, humidity and wind or air movement.