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S.Wang




Biology Revision
B2.1 ­ Cells
Key Words
Light microscopes ­ an instrument used to magnify specimens using lenses and light
Electron microscopes ­ an instrument used to magnify specimens using a beam of electrons
Specialised ­ adapted for a particular function
Tissue ­ a group of specialised cells all…

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S.Wang




Contains cell sap, use to storage and exerts a pressure which supports the cell
Specialised Cells
Blood Diffusion in cells
Red blood cells ­ carries oxygen from lungs to the rest of the body tissues
Cytoplasm contains haemoglobin which carries the oxygen
No nucleus so there are more space…

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Diffusion
Diffusion is the net movement of molecules move from an area of high concentration to an
area of low concentration. They are said to move down a concentration gradient. Diffusion only
happens in gas and solid.
Diffusion is a passive process which means that no energy is needed…

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Dilute solution have a high concentration of water molecules.
Concentrated solution has a low concentration of water molecules.
Osmosis in plant cell
If the plant cell is in a concentrated solution...
The vacuole loses water by osmosis therefore it loses pressure. The cytoplasm has
pulled away from the cell…

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