Stomata are tiny openings or pores located on the lower epidermis of a leaf.
A single pore is called a "sto," and multiple pores are referred to as "stomata."
Stomata are essential for plant gas exchange, surrounded by specialized cells called guard cells.
Structure
Leaf Cross-Section: Displays the arrangement of stomata on the underside of leaves.
Guard Cells:
Surround each sto.
Control the opening and closing of the stomata.
View from underside shows both open and closed stoma.
Function of Stomata
Gas Exchange:
Open stomata allow carbon dioxide (CO2) to diffuse into the leaf airspace and cells.
CO2 moves from a high concentration outside to a lower concentration inside due to its use in photosynthesis.
Oxygen (O2), a photosynthesis byproduct, diffuses out in the opposite direction.
CO2 goes into the leaf for photosynthesis, and O2 comes out as a waste product.
Water Loss:
Water vapor diffuses out of the leaf when stomata are open, moving to a lower concentration outside.
This process is known as transpiration.
Role of Guard Cells
Regulate the size of stomatal pores to control gas exchange and water loss.
When guard cells are swollen with water, they open the stomatal pore.
When dehydrated, guard cells shrivel, closing the pore.
The thick inner wall of guard cells aids in these processes, ensuring efficient gas exchange and transpiration control.
Conclusion
Understanding the role of stomata and guard cells is crucial for understanding plant physiology, especially in relation to photosynthesis, transpiration, and overall plant health.
Additional Resources
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