More On Exchanging Substances Flashcards
Where are villi found?
In the small intestine.
What job does the villi do and how?
They increase surface area so food is absorbed quickly into the blood.
What are the features of villi?
- They have a single layer of surface cells.
- They have a very good blood supply to assist quick absorption.
Where is the exchange surface on a leaf and what is covered all over it?
The exchange surface of a leaf is underneath and it’s covered in tiny holes called stomata.
Name three gases that diffuse through the stomata.
- Carbon dioxide
-Oxygen
-Water vapour
What opens and closes the stomata and why?
Guard cells open close to stomata so that if there is a shortage of water and more is being lost and retained, less water diffuses out through the stomata.
How does the flattened shape of a leaf help gas exchange become more effective?
This increases the exchange surface.
Why are there air spaces between cells in a leaf?
To increase the surface area so that there is more of a chance that carbon dioxide will be absorbed.
Why does water vapour evaporate/diffuse through the leaf?
Because there are lots of water molecules inside the leaf but less outside the leaf, in the air.
What are gills on a fish?
They are the gas exchange surface area in the fish
What is the process of gas exchange, referring to oxygen and carbon dioxide, in a fish?
Water enters the fish through its mouth and passes out through the gills. While this happens, oxygen diffuses out of the water into the blood and carbon dioxide diffuses from the blood into the water.
What are girls made of and what are they for?
Each gill is made of plates called gill filaments which are there to increase surface area for gas exchange.
What structures cover gill filaments?
Lamellae cover filaments and increase surface area of more.
What do lamellae have that speeds up diffusion?
Lots of blood capillaries.
How do lamellae minimise the distance that gases have to diffuse through?
They have a very thin surface layer.
