State that transpiration is the loss of water vapour from the plant through the stomata.
8.1 Transport in Plants
Transpiration: The Water Loss Journey
Imagine a plant as a giant sponge 🌱 that drinks water from the soil. That water travels up the stem in tiny tubes called xylem and finally reaches the leaves. Once there, the plant releases water vapor into the air through tiny pores on the leaf surface called stomata (plural of stomata). This process is known as transpiration – the loss of water vapor from the plant through the stomata. Think of stomata as tiny doors 🚪 that open to let water vapor escape, just like a window letting steam out of a pot of boiling water 🌬️.
- Water moves from soil to leaves via xylem.
- Stomata are the “gates” that control water loss.
- Transpiration helps pull more water up the plant (like a vacuum).
- It also cools the plant, similar to how sweat cools us.
Stomata in Action
| Stomata Feature | What It Does |
|---|---|
| Guard Cells | Open/close the stomatal pore. |
| Stomatal Pore | Allows water vapor to exit. |
| Atmospheric Conditions | Humidity, temperature, and wind affect opening. |
The amount of water lost is influenced by the environment: high temperatures and low humidity increase transpiration, while cool, moist air reduces it. This is why plants in deserts have smaller or fewer stomata – they need to conserve water.
Quick Check
- What is the main function of stomata? Answer: To allow gas exchange and water vapor release.
- Why does a plant need to control transpiration? Answer: To balance water loss with water uptake and maintain cooling.
- How does temperature affect transpiration? Answer: Higher temperatures increase transpiration rates.
Revision
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