dissolved particles (molecules and ions) move in and out of cells by diffusion, particles move from an area of high concentration to an area with a lower concentration down a concentration gradient
to get into cells particles must pass through cell membranes which only allow small molecules through, which is fine for co2 and oxygen
diffusion does not use energy because the particles move spontaneously
distance, concentration gradient and surface area affect the rates of diffusion
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osmosis
osmosis is a special kind of diffusion is is diffusion of water
the membrane is passes through is called a partially permeable membrane
in plants when there is a lot of water there is high turgor pressure and when there is a lack of water the cell becomes flaccid, eventually they collapse and it becomes a plasmolysed cell
in animal cells alot of water may cause the cell to burst due to lack of cell wall, this is called lysis, when there is a lack of water the cell becomes crenated and wrinkles
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