Question

How does respiration occurs in the roots of the plants?

Answer 1

Respiration occurs when glucose (sugar produced during photosynthesis) combines with oxygen to produce useable cellular energy. This energy is used to fuel growth and all of the normal cellular functions. Respiration occurs in all living cells, including leaves and roots.

Since respiration does not require light energy, it can be conducted at night or during the day and even in roots which are under the soil.
Respiration does require oxygen and roots take up oxygen through root hair.
Air is present in between the particles of the soil. The roots take the oxygen by the process of diffusion. Oxygen first diffuses into the root hairs and reaches all other cells of the root for respiration.This oxygen converts glucose to useable energy and carbondioxide is formed as a byproduct. CO2 produced in the cells moves out through the root hairs by the process of diffusion. For respiration, in older roots, where root hair is not present, the exchange of gases takes place through lenticels (tiny openings in the protective layer) by the process of diffusion.

However, it can be problematic for roots which are overwatered or in soils with poor drainage. If roots are inundated for long periods of time they cannot take up oxygen and convert glucose to maintain cell metabolic processes. As a result, waterlogging and excessive irrigation can deprive roots of oxygen, kill root tissue, damage trees, and reduce yield.