Osmosis and diffusion

Permeable

All substances can pass through

selectively permeable

Only allows some substances through but not all

Impermeable

Does not allow any substances to pass through

Diffusion

The movement of molecules from a region of high concentration to a region of low concentration

Diffusion example

Carbon dioxide diffusing out of a leaf and oxygen diffusing in

active transport

The movement of molecules from a region of low concentration to a region of high concentration using energy

Osmosis

The movement of water molecules across a semi permeable membrane from a region of high water concentration to a region of low water concentration

Animal cells in less concentrated solution

The water from the outside will move into the cell and may cause it to burst and die

more concentrated solution

The water will leave the animal cell and the cells shrivel up and may die

a solution of equal concentrations as their cytoplasm

The water will move in and out at the same rate

Turgor

Is the pressure of the cell contents against the wall of a plant

Plant cells in less concentrated solution

When plants are fully swelled they are described as fully turgid

Plant cells in more concentrated solution

The water will leave the plant cell and the cells shrivel up causing the cell membrane to move away from the cell wall this is called plasmolysis

Osmosis and food preservation

If food is placed in sugary or salty solution then any bacteria or fungi present will lose their water in their cells by osmosis and will shrivel up and die

Salting examples

Fish and meat may be stored in a salty solution

Sugaring

Jams and tinned fruits are stored in sugary solutions