B1- More On Exchangijg Substances Flashcards
What gas diffuses into the air spaces within the leaf?
Carbon dioxide
What are the small holes on the underside of the leaf called?
Stomata
What two substances diffuse out of the leaf through the stomata?
Oxygen and water vapour
What controls the size of the stomata?
Guard cells
True or False: The guard cells close the stomata if the plant is losing water faster than it is being replaced by the roots.
True
What is the effect of the flattened shape of the leaf on gas exchange?
Increases the area of the exchange surface
What structure inside the leaf increases the surface area for carbon dioxide to enter?
Air spaces
Fill in the blank: The gills are the _______ exchange surface in fish.
gas
What enters the fish through its mouth?
Water (containing oxygen)
What are the thin plates in the gills called that provide a large surface area for gas exchange?
Gill filaments
What structures cover the gill filaments to further increase surface area?
Lamellae
What do the lamellae contain that speeds up diffusion?
Blood capillaries
What is the purpose of the thin surface layer of cells on the lamellae?
Minimise the distance that gases have to diffuse
How does blood flow through the lamellae compared to water?
Blood flows in one direction and water flows in the opposite direction
What maintains a large concentration gradient between the water and the blood in fish gills?
The opposite flow of blood and water
