Describe transpiration and relate this process with the cell surface and stomatal opening and closing.

Transpiration is the process by which plants lose water vapor to the atmosphere through small pores called stomata that are located primarily on the leaves, although some are also present on stems and flowers. This loss of water vapor helps maintain a transpiration pull that facilitates the movement of water and dissolved minerals from the roots to the leaves through the xylem. Transpiration also plays a critical role in cooling the plant, as the evaporation of water absorbs heat energy from the plant’s surface.
The stomata are controlled by guard cells that regulate their opening and closing. During the day, when photosynthesis occurs, the guard cells take up water, causing them to swell and open the stomata. This allows carbon dioxide to enter for photosynthesis and oxygen to exit as a byproduct. The opening of the stomata also allows water to evaporate from the leaf’s surface.
At night, when photosynthesis ceases, the guard cells lose water and shrink, closing the stomata to prevent unnecessary water loss. The process of transpiration is essential for nutrient transport, temperature regulation, and maintaining plant turgidity.

 

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  3. Explain the internal structure of root and root hair.
  4. Describe how roots take up water and mineral salts by active and passive absorption.
  5. Describe temperature, wind, and humidity as factors affecting the rate of transpiration.
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  7. Describe the process of gaseous exchange in plants.
  8. Explain osmotic adjustment in plants.
  9. Why do gardeners like to use autumn leaves in their soil?
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  11. Write any three osmotic adjustments in hydrophytes.
  12. What is the pattern of gas exchange between plant and environment at the time of dawn and dusk?
  13. Why do plants absorb carbon dioxide and release oxygen during daytime and dusk?
  14. Define the following terms:
  15. Write the difference between:
  16. What is the role of guard cells in stomatal function?
  17. What are the factors that affect the rate of transpiration?
  18. What is the difference between osmosis and diffusion in plants?
  19. What is the role of phloem in plants?
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