Q3 of 6 Page 118

Raju said stem also respire along with leaves in plants. Can you support this Statement? Give your reasons.

In order to carry on respiration, plant cells need oxygen and a means of disposing of carbon dioxide just as animal cells do. Unlike animals, plants have no specialized organs for gas exchange. Each part of the plant such as leaves stems and roots perform their own respiration. In plants respiration takes place at much slower rate as compared to animals. Also, there is very less transportation of respiratory gases from one part of the plant to another.

Respiration in leaves:


In leaves the exchange of respiratory gases takes place through very small pores called stomata (singular stoma). The stomata are present in large number on the lower surface of leaves of plant. Each stoma has a pore at its centre which is surrounded and controlled by two kidney shaped cells called guard cells. When the stoma opens the exchange of gases takes place between the atmosphere and interior of the leaf by the process of diffusion.


stomata.jpg


Respiration in stem:


In the plans having hard and woody stems and mature roots the exchange of gases takes place through lenticels. Lenticels are actually loosely packed dead cells which are present as small pores on the bark of woody plants or old roots. These enable oxygen to reach the intercellular spaces of the interior tissues and carbon dioxide to be released to the atmosphere by the process of diffusion.


lanticels.jpg


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