Movement in and out of Cells

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Diffusion is the net movement of molecules from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement,

Particles more until they reach a state of dynamic equilibrium = particles are still moving but are evenly spread out even in motion

Diffusion is fastest in air

Diffusion in the body

- oxygen goes in lungs

- diffuses into bloodstream until respiration

- carbon dioxide diffuses from bloodstream to lungs

Diffusion of water molecules from a region of their higher concentration (dilute solution) to a region of their lower concentration (concentrated solution) through a semi-permeable membrane

W

Water molecules are small - are able to go through partially-permeable membrane

Wate

Water potential gradient exists between the two sides of the semi-permeable membrane

Root Hair Cells

water moves from soil through cell membrane and into root cells by osmosis

- moves from cell to cell by osmosis until it reaches the xylem

- if then carried up the plant by transpiration

In a concentrated solution

- animal cells shrivel up as water leaves them by osmosis

- plant cells also shrivel up (become flaccid)

- shrivel up and wilt

In a dilute solution

- animal cells burst as water enters them and they don't have a cell wall to support them

- plant cells become turgid (full of water)

DIffusion

Osmosis