To Study Transpiration (Class 10 Biology Practical)
To demonstrate and observe the process of transpiration in plants and measure the rate of water loss
TL;DR: To demonstrate and observe the process of transpiration in plants and measure the rate of water loss
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Aim: To demonstrate and observe the process of transpiration in plants and measure the rate of water loss
Materials Required
- Potted plant with leaves
- Measuring cylinder
- Water
- Oil or Vaseline
- Transparent plastic bag
- Thermometer
- Hygrometer
- Balance
- Watch or timer
Theory
Transpiration is loss of water vapor from plant through leaves. It occurs mainly through stomata on leaf surface. Transpiration helps in water transport, nutrient absorption, and temperature regulation. Rate of transpiration depends on temperature, humidity, wind, and leaf surface area.
Procedure
- Water the potted plant thoroughly
- Weigh the pot and plant initially
- Place plant in bright light and normal room conditions
- Measure water loss daily for one week by weighing
- Record weight loss as measure of transpiration
- Set up second plant with leaves covered with oil to reduce transpiration
- Compare water loss between normal and oiled plant
- Measure temperature and humidity during experiment
- Plot graph of water loss versus time
Observation
Normal plant loses weight indicating water loss through transpiration. Oiled plant loses less weight as stomata are blocked. Water loss increases with temperature. Loss is greater in dry conditions.
Result
Transpiration successfully demonstrated. Comparison shows stomata are main pathway for transpiration. Factors affecting transpiration identified.
Precautions
- Water plant adequately before starting experiment
- Keep plant away from direct strong sunlight initially
- Use same location for all pots to ensure consistent conditions
- Avoid physical damage to leaves during observation
- Keep plant healthy throughout experiment duration
Viva Questions
Define transpiration.
Transpiration is loss of water vapor from plant surface, mainly through stomata on leaves. It is essential for plant growth and survival.
What are the factors affecting transpiration?
Factors affecting transpiration are temperature, humidity, wind speed, leaf surface area, availability of water, and light intensity.
How does temperature affect transpiration?
Increase in temperature increases transpiration rate because warmer air has greater evaporating power and stomata open wider.
What is the role of stomata in transpiration?
Stomata are pores on leaf surface that allow water vapor to escape. They can open and close to regulate transpiration rate.
How is transpiration important for plants?
Transpiration helps in water transport from roots to leaves, nutrient absorption, temperature regulation, and maintaining turgor pressure.
Why do plants lose less water in humid conditions?
In humid conditions, vapor pressure gradient between leaf and air is smaller, so less water evaporates from leaf surface.
More Class 10 Biology Practicals
- To Test for Starch, Protein, and Fats in Food
- To Study Osmosis Using a Potato Osmometer
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- To Observe Stomata on Leaf Surface
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