Gas exchange - plants

What are the pores in the epidermis of the leaf through which gas exchange takes place called?

• Phloem

• Chloroplasts

• Xylem

• Stomata

Why do stomata need to be open all the time?

• To prevent transpiration

• To allow gas exchange and photosynthesis

• To regulate temperature

• To conserve water

What causes water loss through stomata?

• Photosynthesis

• Transpiration

• Respiration

• Abscisic acid

Which plant hormone signals stomata to close during water deficiencies?

• Gibberellin

• Cytokinin

• Abscisic acid

• Auxin

What active process makes guard cells turgid and opens stomata?

• Uptake of sodium ions

• Uptake of potassium ions

• Uptake of magnesium ions

• Uptake of calcium ions

In what conditions do stomata close?

• Low temperature

• High humidity

• Darkness

• High wind speed

How does temperature affect the rate of transpiration?

• Increases water evaporation

• Decreases water evaporation

• Increases water retention

• Decreases water absorption

What effect does lower humidity have on transpiration?

• Stops transpiration

• No effect on transpiration

• Decreases transpiration

• Increases transpiration

What happens to the rate of transpiration with increased air movement?

• Stops completely

• Decreases

• Remains constant

• Increases

What is the role of light in the opening and closing of stomata?

• Has no effect on stomata

• Stimulates transpiration

• Causes stomata to close

• Causes stomata to open