What is transpiration ? Discuss the role
the that transpiration plays in a plant &
the factour that affect the rate of
transpiration
Answers
Answer:
Like all living organism, plants also require an excretory system to discharge excess water from their body. This process of elimination of excess water from the plant body is known as transpiration. It is generally the evaporation of water from the surface of the leaves.
During the process of transpiration, water molecules in the plant tissues are removed from the aerial parts of the plants. Only a small amount of water absorbed by the plants is utilised in growth and development. The rest is eliminated in the form of transpiration.
Factors Affecting Transpiration in Plants
Different factors affecting the rate of transpiration are:
Cellular Factors
The cellular factors affecting the rate of transpiration are:
The orientation of leaf,
The water status of the plant,
Structural Peculiarities of the leaf,
Total number and distribution of stomata in a leaf.
Environmental Factors
The environmental factors affecting the rate of transpiration are:
Light,
Humidity,
Temperature,
Atmospheric pressure,
Wind speed or velocity.
Relative Humidity
The amount of water vapour present in the air at a particular time and temperature is expressed as a percentage of the amount required for saturation at the same temperature. The rate of transpiration is inversely proportional to relative humidity. More the relative humidity less is the transpirate rate.
Temperature
A high temperature lowers the relative humidity and opens the stomata even in darkness. As a result, the rate of transpiration increases.
Light
The stomata open during the day and close in the dark. Presence of light is directly proportional to the rate of transpiration.
Air
If the air is still, the transpiration rate is low. This is because the water vapour accumulates around the transpiring organs and reduce the diffusion pressure deficit of the air.
If the air is moving, the saturated air around the leaves is removed and the transpiration rate increases.
Water Availability
The transpiration rate is directly proportional to the absorption of water by the roots from the soil. A decrease in water absorption causes the closure of stomata and wilting, thereby reducing the rate of transpiration.
Surface Area of the Leaves
A leaf having more surface area will show more transpiration rate than the leaf with a lesser surface area.
Also Read: Difference between Transpiration and Guttation
Ascent of Saps
When water evaporates through the leaves, a pull is created through the xylem, and water moves back to the leaves. This is known as the transpiration pull.
The ascent of sap that is driven by transpiration depends on the following properties of water:
Cohesion – This is the mutual attraction between molecules of water.
Adhesion – The attraction of water molecules towards polar surfaces.
Surface tension – The molecules of water are more attracted to each other in the liquid phase than in the gas phase.
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Answer:
transpiration is the process when leaves lose their water
Explanation:
Leaves also release water from plant through stomata. This is called transpiration. It helps in cooling down the leaves. It also has another important function. As the water escapes from the leaves, the roots pull more water to compensate for this loss. This water brings with it important nutrients required by the plant from the soil. Transpiration plays an important role in the water cycle, by increasing the moisture in the air.
To study the transpiration in plants, you have to take a healthy potted plant and water it. Select the branch with a number of leaves, and enclose it in a transparent polythene bag. Tie the mouth of bag. Take another similar polythene bag and tie its mouth.
Keep the potted plant and the other bag in the sun. Observe after few hours. Can you see the water droplets in the polythene bag covering the branch? Are there water droplets in the other bag? Where did the droplets come from? because of the transpiration in the leaf