The Stomata of Leaves

Stomata are small pores on plant leaves and stems, crucial for gas exchange. In dicots, they are mostly on the lower leaf surface, while in monocots, they are evenly distributed. Stomata open and close due to guard cell movements, influenced by environmental conditions. They allow carbon dioxide in for photosynthesis and release oxygen and water vapor. Factors like light, humidity, and carbon dioxide levels affect stomatal behavior. Abscisic acid, a plant hormone, also plays a role in closing stomata to prevent water loss.

Where are stomata primarily located in dicot plants?

• Equally on both sides of the leaves

• On the lower surface of the leaves

• Only on the stems

• On the upper surface of the leaves

What is the primary function of stomata in plants?

• To absorb nutrients from the soil

• To facilitate gas exchange with the atmosphere

• To protect the plant from pests

• To store water for the plant

What causes the guard cells to swell and open the stomatal pore?

• Uptake of potassium ions and water by osmosis

• Release of abscisic acid

• Decrease in potassium ions

• Increase in carbon dioxide

Under what condition do potassium ions exit the guard cells?

• When the plant is in shade

• During strong light

• When carbon dioxide is abundant

• When humidity is high

What role does abscisic acid play in stomatal function?

• It opens the stomata

• It closes the stomata to prevent water loss

• It enhances nutrient absorption

• It increases photosynthesis