Question

Stomata are usually found in higher numbers on the abaxial or bottom surface of a leaf. Demonstrate why this is the case by explaining the advantage of such an arrangement.

a) The bottom surface protects stomata from direct sunlight, reducing water loss.
b) The underside allows for better gas exchange due to cooler temperatures.
c) The bottom placement prevents excessive transpiration and desiccation.
d) The abaxial surface enhances photosynthetic efficiency by minimizing water loss.

Answer 1

Stomata are commonly located on the underside of leaves to protect them from direct sunlight, minimize water loss, and ensure more efficient gas exchange. Guard cells regulate the opening and closing of stomata based on environmental conditions, balancing photosynthesis and water loss.

Coreect option is c) The bottom placement prevents excessive transpiration and desiccation.

Step-by-step explanation:

Stomata are typically found in greater numbers on the abaxial or bottom surface of a leaf. This arrangement has several advantages:

• The bottom surface protects stomata from direct sunlight, which reduces water loss through transpiration, thus minimizing water loss.
• This placement allows the leaf to maintain a cooler temperature on the underside, which is conducive for efficient gas exchange.
• By having stomata on the abaxial surface, the plants also prevent excessive transpiration and potential desiccation, contributing to better water balance within the plant.

Guard cells play a crucial role as they open and close the stomata in response to various environmental factors to balance the need for CO₂ for photosynthesis with the need to minimise water loss.