Topic 1b Flashcards
What is diffusion
The spreading out of particles from an area of higher concentration to lower concentration
What type of molecule can fit through the cell membrane?
Very small molecules
What affects the rate of diffusion(3)
Concentration gradient
Temperature
Surface area
What is the net movement
The overall movement of particles from one side in diffusion
The bigger the concentration gradient the __________ the rate of diffusion
Why?
Faster
The net movement from one side is greater
The higher the temperature the _________ the rate of diffusion
Why
Faster
The particles move around quicker as they have more energy
The larger the surface area the _________ the rate of diffusion
Why
Faster
More particles can pass through at once
What is osmosis
The movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower concentration
What is water trying to do during osmosis?
‘Even up’ the concentration either side of the membrane
What is active transport?
The movement of particles against a concentration gradient ( lower concentration to higher)
Do each of these require energy or not?
Diffusion
Osmosis
Active transport
No
No
Yes
Why do multicellular organisms need exchange surface for efficient diffusion
Small surface area compared to volume
Where does gass exchange happen
Lungs
What are alveoli specialised to do
How? (3)
Maximise diffusion of oxygen and co2
Large surface area
Thin walls
Good blood supply
Where are villi located
Small intestine
What are villi used for (2)
Increasing surface area
Good blood supply for quick absorption
How is the structure of leaves good at diffusion (3)
The underneath is an exchange surface with stomata
Stomata size controlled by guard cells
Shape increases area of exchange surface
