B4.8 Flashcards
Q: What are the small openings on the leaf surface called?
A: Stomata
Q: When do stomata open?
A: When the plant needs to allow air into the leaves.
Q: How does CO2 enter the leaf?
A: Diffuses from the atmosphere into the air spaces and then into the cells down a concentration gradient.
Q: What happens to oxygen produced by photosynthesis in leaves?
A: It is removed by diffusion into the surrounding air.
Q: Why is it important for oxygen to diffuse out of the leaf?
A: To maintain a concentration gradient for oxygen to diffuse from the cells into the air spaces of the leaf.
Q: What controls the size of the stomata and their opening and closing?
A: Guard cells
Q: What happens when stomata are open?
A: Plants lose water vapour.
Q: How does water vapour leave the leaf?
A: Water vapour evaporates from the cells lining the air spaces and then passes out through the stomata by diffusion.
Q: What is the process called when plants lose water vapour?
A: Transpiration
Q: What happens as water evaporates from the surface of the leaves?
A: More water is pulled up through the xylem to take its place.
Q: What is the constant movement of water molecules through the xylem from the roots to the leaves called?
A: Transpiration stream
Q: What drives the transpiration stream?
A: The evaporation of water from the leaves.
Q: What affects the rate of transpiration?
A: Anything that affects the rate of evaporation.
Q: What maintains the concentration gradient for oxygen in the leaf?
A: The diffusion of oxygen from the cells into the air spaces and out through the stomata.
Q: What role do guard cells play in plant respiration?
A: They control the opening and closing of stomata.
