Gas and Solute Exchange Flashcards
What three ways to substances move?
Diffusion, Osmosis and Active Transport
Life processes need [ ]` before they can happen
gases or other dissolved substances
What is diffusion?
Where particles move from an area of high concentration to an area of low concentration.
What is an exchange surface, what do they do?
In life processes, the gases and dissolved substances have to move through some sort of exchange surface. The exchange surface structures have to allow enough of the necessary substances to pass through.
How are exchange surfaces adapted? [4]
Thin - so substances have a short distance to diffuse
Large surface area - so lots of a substance can diffuse at once
Lots of blood vessels (in animals) - to get stuff into and out of the blood quickly
Ventilated (in animals) - air moves in and out
Where on the plant is the exchange surface?
The underside of the leaf
Where does the carbon dioxide diffuse through?
The stomata
What diffuses out of the stomata?
Water vapour and carbon dioxide
What controls when stuff goes in and out of stomata? Why do they do this?
Guard cells
They close the stomata if the plant is losing water faster than it is being replaced by the roots. Without these guard cells the plant would soon wilt
Why is a flat leaf good?
Increases the area of the exchange surface so that it is more effective
Why are air spaces inside the leaf good?
Increase the surface area so there’s more chance for CO2 to get into cells
When is evaporation quickest?
Hot, dry, windy conditions
Water vapour evaporates fro the cells inside the leaf. Why does it then escape?
It then escapes through diffusion because there’s a lot of water inside the leaf and less of it in the air outside.
