Diffusion, Osmosis and Active Transport Flashcards
(12 cards)
Define diffusion
The movement of particles from a high concentration to a lo concentration
What can increase the rate of diffusion?
Greater concentration gradient
Higher temperature so particles have more energy to move
Where does diffusion occur
Diffuse through cell membrane for molecules like oxygen, glucose, amino acids and water
What is osmosis
Movement of water from a high concentration to a low concentration through a semi-permeable membrane
Practical for osmosis
Cut a potato into a cube and measure the mass using a scale
Add the potato to a sugar solution with a defined concentration
Remove the potato and pat dry with a paper towel before recording the new mass and calculate the percentage mass change
If the mass increased water entered the potato as osmosis
Define active transport
The movement of particles from a low concentration to a high concentration using energy
Example of active transport
Root hair cells absorb minerals from the soil from a low concentration to a high concentration
Absorbing glucose from digestion in the small intestine
How are cells adapted to be more efficient as exchanging surfaces
Thin cell membranes for a short diffusion pathway
Large surface ares
Lots of blood vessles for a constant blood supply
How are aveoli specialised to maximise diffusion
Large surface area
Moist lining for dissolving gases
Thin walls
Constant blood supply
How are villi specialised to maximise diffusion
Single layer surface cells
Good bloos supply
How are leaves specialised to maximise diffusion
Stomata are where carbon dioxide enter the leaf and where oxygen and water vapour exit the leaf
Flat leaf shape for increased surface area
Large air spaces
How are gills specialised to maximise diffusion
Oxygen diffuses into the gills whilst carbon dioxide diffuses into the water
Covered in lamellae which increase the surface area and have a constant blood supply
