No, stomata do not prevent water loss; instead, they regulate it.
How Stomata Control Water Loss
Stomata are tiny pores found on the surface of leaves. They are crucial for a plant's survival because they control the exchange of gases – taking in carbon dioxide for photosynthesis and releasing oxygen. However, this gas exchange comes at a cost: water loss through transpiration.
- Regulation, not prevention: Stomata don't block water loss entirely. Their primary function is to control the rate of water loss by opening and closing. When open, water vapor escapes, but this also allows for the essential intake of carbon dioxide.
- Guard cells: Specialized cells called guard cells surround each stoma. These cells change shape, opening or closing the stomata in response to environmental conditions. For example, they close during low light conditions or when the plant is stressed by water scarcity. This reduces water loss.
- Balancing act: Plants must strike a balance. While they need to conserve water, they also require carbon dioxide for photosynthesis. Stomata facilitate this delicate balance by adjusting their opening and closing based on factors like light intensity, temperature, and humidity.
The provided reference states: "Stomata regulate the loss of water and the exchange of gas by opening and closing. They allow water vapour and oxygen out of the leaf and into the leaf with carbon dioxide." This clearly indicates that stomata manage water loss, not prevent it.
