Solutions Solute – The substance that dissolves to form a solution eg salt Solvent – The...

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Transcript of Solutions Solute – The substance that dissolves to form a solution eg salt Solvent – The...

SolutionsSolute – The substance that dissolves to form a solution eg saltSolvent – The substance in which a solute dissolves eg waterSolution – A mixture of one or more solutes dissolved in a solvent eg sea water

Solute

Solvent

DIFFUSION & OSMOSIS

DIFFUSION• Diffusion animation

Diffusion is the net movement of particles from a region of higher concentration to a region of relatively lower

concentration. No input of energy is required.

DIFFUSION & OSMOSISOSMOSIS• Osmosis animation

Osmosis is the net movement of a solvent, usually water, across a

differentially permeable membrane. The net movement of water occurs

from the side of the membrane where there is a weak solution (high

water concentration, low solute concentration) to the side of the

membrane where there is a strong solution(low water concentration,

high solute concentration).Osmosis does not require energy

input.

Amoeba are small unicellular organismswith a large SA:V

Amoeba in action 1Amoeba in action 2

Some substances can diffuse into /out of these cells very efficiently as a result of the large SA: V ratioLarger food particles can be engulfed: phagoctosis

Plasma Membranes

Functions of the cell membrane include:1. It gives a definite shape to the cell.2. It contains and provides protection to the internal contents of the cell.3. It is selectively permeable.4. It can take in solid and liquid materials by in folding.5. In animal cells, it is involved in the formation of vesicles, cilia, flagella, microvilli, etc. Plasma Membrane overview 5 min

Passive diffusion across a membrane

Openings both sides eg channels for ion transfer

Binds hormones and other substances

Attach to carbohydrates act as antigens

Link cells together

Fluid Mosaic model of plasma membranes

Web page including good animation

Cell-Membrane-Function