How the plant respiratory system works?

Answer 1

Plants do not have respiratory organs such as gills or lungs, they need carbon to store energy in the form of glucose. Therefore they retrieve carbon dioxide from the air. As a rest product of photosynthesis, oxygen is produced. Plants have small holes on the bottom of their leaves called stomata. The stomata are used for gas exchange and to bring carbon dioxide into the leaf and the cells of the plant can remove the oxygen. The carbon dioxide from the atmosphere diffuses through the stomata into the air spaces inside the leaf, which is in direct contact with the spongy and palisade mesophyll cells. They are normally open in the day light and closed at night. If the stomata are on the branches, they are called lenticels.

Plants have cells enclosing the stomata named guard cells. These cells are responsible for controlling the size of the stomata, defence against small insects and stopping water from escaping out of the stomata. The guard cells squeeze shut, closing the stomata.

When CO2 levels are low, like at night when the stomata are closed, the enzyme reaction that normally produces glucose and oxygen reverses and starts using oxygen and producing CO2. This is called photorespiration and is a wastefull process for the plant. To prevent this process specialized biochemical additons have evolved in the plant world: C4 and CAM metabolisms prevent respiration by seperating parts of the parts of the photosythesis process into different parts of the plant cell.