“Plant respiration is the chemical reaction by which plants cells stay alive.” The process of respiration is expressed as:
Glucose + Oxygen → Carbon Dioxide + Water (+ Energy)
Respiration in Roots :
The process of respiration in roots is carried out in the following manner:
• Air occurs in several interspaces of soil. The hairs of the roots are in direct contact with
them.
• Oxygen of the soil gets diffused via root hairs and reaches all internal cells of the root
for respiration.
• Carbon dioxide produced during the diffusion is released in the opposite direction.
Respiration in Stems :
• In the condition of water logging, air gets deficient in soil and in this case, metabolic
activity of the roots declines. The stems of herbaceous plants possess stomata and the
air gets diffused via it and reaches the cells for respiration.
• The carbon dioxide produced during the process gets diffused in the air via stomata.
Respiration in Leaves :
• When the stems are woody, this gaseous exchange is carried out by lenticels. Leaves of
the plants have tiny pores which are referred as stomata. The exchange of gases takes
place by the process of diffusion via stomata. The stomata are present in large number
on lower surface of leaves of plant. Each stoma is surrounded and controlled by Guard
Cells (two kidney shaped cells). Then the stoma, open gaseous exchange takes place
between atmosphere and interior of leaves.
Types of Respiration :
Respiration is of two types :
• Aerobic Respiration: In this type of respiration, the food substances are completely
oxidized into H2O and CO2 with the release of energy. It requires atmospheric oxygen
and all higher organisms respire aerobically. Following figure shows the steps included
in Aerobic Respiration.
• Anaerobic Respiration: In this type of respiration, partial oxidation of food takes place
and energy is released in the absence of oxygen. This type of respiration occurs in
prokaryotic organisms like bacteria and yeast. Ethyl alcohol and carbon dioxide are
formed in this process.
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