Question

Discuss the exchange of gases in plants.

Accepted Answer

The exchange of gases between a plant and its surrounding takes place through the leaves. Plants need oxygen for respiration and carbon dioxide to carry out photosynthesis. These gases diffuse into the intercellular spaces through tiny pores on the under-surface of the leaf called the stomata. The stomata are surrounded by two bean-shaped guard cells that regulates the opening and closing of the stomatal pore.
In woody plants, the gaseous exchange also occurs through the lenticels, apart from the stomata. Lenticels are small openings in the pits of the bark of woody plants.

Plants undergo respiration throughout the day and night while photosynthesis occurs only during the day in the presence of sunlight.

During the day:
The carbon dioxide produced by plants during respiration is used directly by them for photosynthesis. Thus, plants do not liberate CO₂ into the atmosphere during the day, in fact, they use additional CO₂ from the air for photosynthesis. The process of photosynthesis generates oxygen, of which some amount is utilised by the plants for respiration while rest is liberated into the air through the stomatal pores.

During the night:
At night, plants do not undergo photosynthesis, thus, no oxygen is released. Respiration occurs even during the night but the carbon dioxide produced is not used by the plants and thus, released in the air.

Discuss the exchange of gases in plants.

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