Respiration in Plants

Plants also use oxygen and release carbon dioxide during respiration. 

• All parts of a plant (root, stem and leaves) respire individually . 
• Gases do not need to be transported to other body parts of the plant.
• Occurs at a slow rate.

Exchange of Gases: Diffusion

• Since plants have a branching shape, they have a much larger surface area than volume. 
• Thus they obtain oxygen by diffusion in all their parts. 

Respiration in roots:

• Roots of plants absorb air present in the soil by diffusion.  
• The roots have small root hairs that are in contact with the air pockets in the soil. 
• Carbon dioxide produced in the root cells is expelled through root hair by diffusion.

Respiration in Stem:

• Stems of herbs have stomata .
• Oxygen from air diffuses into the stomata and reaches all the cells from respiration.
• Carbon dioxide also diffuses out from the stomata.
• In woody stems, the bark has lenticels for gaseous exchange . Oxygen diffuses into the woody stem and reaches all inner cells for respiration. CO2 diffuses out from the same lenticels.

Respiration in Leaves:

• Leaves have tiny pores called stomata where the gaseous exchange takes place. 
• Oxygen from air diffuses into the stomata and reaches all the cells from respiration.
• Carbon dioxide also diffuses out from the stomata.
• Respiration occurs in leaves during the day as well as night . Photosynthesis only occurs during the day.