Stomatal opening and closing

Biology

Concept: Stomatal Opening and closing.

Stomata are tiny pores present on the surface of the leaves. Massive amounts of gaseous exchange takes place in the leaves through these pores for the purpose of photosynthesis. But it is important to note here that exchange of gases occurs across the surface of stems, roots and leaves as well.

Since large amounts of water can also be lost through these stomata, the plant closes these pores when it does not need carbon dioxide for photosynthesis. The opening and closing of the pore is a function of the guard cells. The guard cells swell when water flows into them, causing the stomatal pore to open. Similarly the pore closes if the guard cells shrink.

Some Plants receive less water from the environment, hence they cannot afford to loose much water through transpiration. That is why they adapt themselves to the scarcity of water.

Such plants which adapt themselves to loose less water, are called Xerophytes. Example:- Cactus.