diffusion

diffusion

the speading out of molecules from a region of high concentration to lower concentration.

takes place…..

diffusion takes place along a concentraion gradiet (high to low concentration)

passive…

diffusion is a passive process, molecules do not need energy to move

everyday examples of diffusion

smell of perfume, baking bread

biological examples

carbon dixoide diffusing into a leafe, oxygen diffusing out of a leafe, oxygen diffusion from the blood into muscle cell.

permeable

the substance can pass through the membrane

impermeable

the substance can not pass thorugh the membrane

selectivly permeable

allows some not all molecules pass through the membrane

substances can pass through freely

water, oxygen, carbon dixoide

substances to big to pass through

sugar starch protein

protein channels

cells have specail channel proteins to transport substances when neccesary e.g glucose in respiration

solevant

a soloution that can disslove other substances

solute

a substance that has been dissolved e.g sugar

soloution

a mixture of the solute and solouton e.g salt water

osmosis

the spreading out of water concentration from an area of high concentration to a region of lower concentration across a selectivly permeable membrane

what is osmois a special type of

a specail type of diffusion involves only water and a selectivly permeable membrane

Osmosis - animal cells in a soloutioon as the same concentration as their cytoplasam (3)

1. water will move in and out at a constant rate in the cell membrane

2. the volume of the cell with remain the same

3. note - seawater is usally the same concentration as the cytoplasams in aquatic animals.

animal cells in a soloution that is less concentrate then their cytoplasam

1. water will move into the cell due to osmosis, the high concentration of water is outside the cell

2. water moves from an area of high to lower concentration

3. the cell will enlarge and may burst and die due to lack of cell wall

4. this can happen to red blood cells if plasma is too dilute

5. some organisms have a way to prevent bursting

6. amoeba is a unicellullar organism that lives in fresh water ponds/pools

7. they have contractile vacuoles to collect water like a sponge and expel it to prevent bursting, in this way they can cantrol osmoregulation

animal cells in a soloution higher concentrated then their cytoplasm

1. water will movie out of the cell as the higher concentration is outside of the cell

2. water movies from high to lower concentration so water moves out

3. this can cause cell to shivel + possibly die

4. can happenn to red blood cells if plasma is to concentrated