Transpiration - Plant Water Loss (GCSE Biology)
Plant Water Loss
Water Loss
Stomata and Guard Cells
The role of stomata and guard cells are to control gas exchange and water loss.
- Stomata allow the evaporation of water. Stomata are small gaps in the leaves that allow water to move through.
- Guard cells open and close stomata. Guard cells open the stomata when they take in water. This allows gas exchange for photosynthesis. When there is less water, the guard cells become flaccid and close the
stomata. Less water can be lost through evaporation then. - Stomata are found on the underside of leaves. The stomata are found on the underside of the leaves as this part of the leaf is cooler than the top of the leaf.
Water Loss and Leaf Structure
- Water is able to diffuse through the leaf due to the many interconnecting air spaces. This increases the diffusion of the water out of the plant’s leaves.
- Mesophyll cells in the leaves have a large surface area. This also means water vapour can diffuse out of the plant quite quickly thus, increasing water loss.
Wilting
- Wiling is due to the lack of water. When there is not enough water, cells become flaccid (refer back to osmosis chapter) and lose water to the surrounding area. Hence they wilt.
- When plants have sufficient water, their cells become turgid. This is because they draw in water from the surrounding soil through osmosis.
Transpiration is the process by which water is lost from a plant’s leaves in the form of water vapor. This water vapor is released into the air through tiny openings on the undersides of the leaves called stomata.
Transpiration is important for several reasons. First, it helps to regulate the temperature of the plant and prevent overheating. Second, it helps to transport water and nutrients from the roots to the rest of the plant. Finally, it also helps to maintain the plant’s turgor pressure, which is necessary for the plant to maintain its shape and structure.
Several factors can affect the rate of transpiration, including light intensity, temperature, humidity, and wind. Light intensity increases transpiration, while high humidity and low wind speed decrease transpiration.
Transpiration creates a pressure difference between the roots and the rest of the plant, which pulls water and nutrients up from the roots and into the rest of the plant. This process is known as the “transpiration stream.”
The rate of transpiration can be measured by placing a potted plant in a closed container with a piece of moist paper on the bottom. The loss of water from the plant will cause the paper to become dry, and the rate of transpiration can be calculated based on the amount of water lost over a certain period of time.
Stomatal transpiration refers to the water loss that occurs through the stomata. This is the most significant form of transpiration, as it accounts for the majority of the water loss from the plant. Stomatal transpiration is important because it helps to regulate the plant’s temperature and maintain its turgor pressure.
Plants have evolved several adaptations to conserve water during transpiration. For example, some plants have developed smaller stomata to reduce water loss, while others have developed thicker cuticles to reduce evaporation from the leaves. Additionally, some plants have evolved structures like succulent leaves and stems that can store water, reducing the need for frequent watering.
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