B3 - Gas and Solute Exchange Flashcards
What substances are involved in respiration and what do they do?
Glucose and oxygen move in and out of cells.
What do exchange surfaces do?
Allow enough of a substance through.
What are the 4 factors of a good exchange surface and how do they help?
Thin: shorter diffusion distance.Large surface area: lots at once.Blood vessels: in/out of blood quickly.Ventilated.
Do bigger organisms find it easier or harder to exchange substances and why?
Harder, because they’re more spread out and further apart.
How does diffusion work in a plant?
It diffuses into air spaces in the underside of the leaves through the stomata. It then diffuses into cells for photosynthesis.
What are the role of stomata?
They let water vapour and oxygen out.
What are the role of guard cells?
They control the stomata size.
What would happen if plants didn’t have guard cells?
They would wilt.
What happens if a plant is losing too much water?
The guard cells will close.
What sort of shape do leaves have and why does this help?
They have a flattened shape which increases their area, making them more effective.
What does photosynthesis need in regards to substances?
CO2 and water in cells.