through the porous cell walls into the cytoplasm. Here the sugar is broken down into carbon dioxide and water with the liberation of the energy. The carbon dioxide passes out into the air spaces by a similar method. The whole system works by diffusion; as the oxygen is used up by the cells a gradient develops between the cells and the air in the spaces. Similarly between the air in the spaces and the air outside the stomata and lenticels, so oxygen passes in. In the same way, as more carbon dioxide is released by the cells a gradient occurs in the reverse direction and it passes out to the environment.

Take a handful of moong or Bengalgram seeds. Soak the seeds in water a day before to perform your experiment. Keep these soaked seeds in a cloth pouch and tie with a string tightly. Keep the cloth pouch in a corner of your class room. Next day collect the sprouts/ germinated seeds from the pouch, keep it in a glass bottle/plastic bottle(around 200 ml capacity). Take a fig-16: Aerial/respiratory roots

Most plants can aerate their roots by taking in the oxygen through the lenticels or through the surface of their root hairs (as their walls are very thin). They obtain oxygen from the air spaces existing between the soil particles. But, plants which grow in very wet places, such as ponds or marshy soils, are unable to obtain oxygen. They are adapted to these water-logged

The most usual adaptation is to have a hollow stem. Next time when you are by a pond or marsh cut the stems of some of the plants which are growing there and see how many are hollow compared with a similar number of species of plants growing in normal soil. The problem of air transport is more difficult for trees and not many survive with their roots permanently in water. An exception is the mangrove tree of the tropics which have aerial roots above the soil surface and takes in oxygen through these roots.

To know more about respiration in plants we should perform the following activities.

Take a handful of moong or Bengalgram seeds.

Soak the seeds in water a day before to perform your experiment. Keep these soaked seeds in a cloth pouch and tie with a string tightly. Keep the cloth pouch in a corner of your class room. Next day collect the sprouts/ germinated seeds from the pouch, keep it in a glass bottle/plastic bottle(around 200 ml capacity). Take a