* Stomata: Tiny pores on the surface of leaves, primarily on the underside.
* Guard cells: Specialized cells surrounding each stoma. They control the opening and closing of the stoma.
* Air: Carbon dioxide (CO2) enters the leaf through the stomata for photosynthesis. Oxygen (O2), a byproduct of photosynthesis, exits through the stomata.
* Water: Water enters the leaf through the roots and travels upwards via the xylem, eventually reaching the leaves. While some water vapor exits through the stomata (transpiration), this is a secondary function.
How stomata work:
* Opening: When guard cells are turgid (full of water), they swell and open the stoma. This allows for gas exchange and transpiration.
* Closing: When guard cells lose water and become flaccid, they close the stoma, reducing water loss and gas exchange.
Factors influencing stomata opening and closing:
* Light: Stomata generally open in the presence of light and close in darkness.
* CO2 concentration: High CO2 levels inside the leaf can signal the stomata to close.
* Water availability: When water is scarce, stomata close to prevent excessive water loss.
* Temperature: Extreme temperatures can also trigger stomata closure.
Overall: Stomata are essential for a plant's survival, enabling them to perform photosynthesis and regulate water loss.
