Topics: Leaf, Plant physiology, Transpiration Pages: 1 (360 words) Published: November 2, 2014

Title: Transpiration
Aim: To study the significance of the pattern of stomatal distribution in Coleus and Lucky bamboo leaf Theory: Transpiration is the loss of water vapour from the surface of the plants due to evaporation. Transpiration can help the uptake of water in the xylem due to transpiration pull. During transpiration, mesophyll cells lose water continuously to the air space. This decreases the water potential of the mesophyll cells. Water is then drawn from their neighbouring cells by osmosis. The neighbouring cells continue to draw water from their neighbouring cells in the same way. Eventually, water is pulled from the xylem vessels. As a result, a water potential gradient is set up, causing water to flow from the xylem along a chain of cells to the most distant mesophyll cells. Morever, a force is created to pull water up the xylem vessels. This force is called the transpiration pull. The rate of transpiration can be measured by a potometer. A bubble potometer can be used to measure the rate of water uptake by a leafy shoot. Since most of the water taken up by plants will eventually be lost through transpiration, it is assumed that the rate of water uptake is the same as the rate of transpiration. The rate of transpiration increases with an increase in light intensity. As the light intensity increases, the stomata open wider. More water vapour in the air space diffuses out through the stomata. In darkness, the stomata close, so that the rate of transpiration decreases. In this experiment, 4 tests will be done as we have to do experiments on both the upper and lower side of the leaf also, we have to check which side of the leaf has more stomata and if the stomata density is the same. Dependent variable: Transpiration rate

Independent variable: Two different types of leaves, so two different experiments Control variable: Light – the light intensity should be the same in all tests. Procedures:Draw the set up
Location of light source
Position of...
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