BY WHICH MEANS GASEOUS EXCHANGE OCCURS IN PLANTS

Gaseous Exchange in Plants

GASEOUS EXCHANGE IN PLANTS:

Plants also get their energy from respiration. No special organ or system is present in plants for gaseous exchange. Each and every cell of every part of plant carries out exchange of gases according to its needs. The transport system of plants which includes large conducting vessels i.e. xylem and phloem are not involved in the diffusion of gases to the plants.

Air spaces:

In most cells of Mesophyll (the inner tissue (parenchyma) of a leaf, containing many chloroplasts) are specialized for photosynthesis. There are present large air sacs. These air spaces are directly involved in gaseous exchange.

Stomata:

Stomata are main sites of exchange of gases in plants. Largely stomata are present in the leaves but these are also present in the young stem. Chief function of stomata is gaseous exchange.

Structure of Stomata

Also Read>> Events Happening During Opening and Closing of Stomata

Lenticels:

In the older parts of the plant i.e. both stems and roots, cork tissues are present. Cork tissues are formed of dead cells just below the epidermis. The cork tissue has special pores called lenticels which are involved in gaseous exchange.

Procurement of Oxygen by Land Plants:

Land plants get their oxygen directly from air which enters the leaves through stomata. A large number of stomata are present on the surface of leaves. They are more abundant on lower side of the leaf than upper side. It is .estimated that there are 12000 stomata per square centimeter of leaf surface in tobacco plant. These stomata lead to the empty spaces (Air spaces) between Mesophyll cells. The air spaces may comprise up to 40% of total volume of the leaf. In the air spaces the exchange of gases from the moist surface of Mesophyll cells takes place at once. In this way gaseous exchange took place in plants.

The roots of the land plants get their oxygen from the air existing in the spaces between the soil particles.