Diffusion is one of the ways that substances ener and leave cells.
- In an animal cell, oxygen and glucose diffuse throught the membrane (controls leaves the cell) into the cell. This is because there is more oxygen and glucose outside the cell than there is inside.
- In a plant cell, carbon dioxide diffuses in. Oxygen and glucose diffuse out.
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Unicellular organisms have just one cell.
- Euglena has a long whip-like structure to help it move through water
- Amoeba can make finger-like projections to catch food
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Organisations of cells
- Cells of the same type carrying out the smae function are usually grouped together to form a tissue.
- Different types of tissue are grouped together to form organs.
- Different types of organs are grouped together to form organ systems
- Different types of organ systems work together to form the organism, e.g. a human being
Examples of a cell and organ systems include:
- Bone cells in the skeletal system
- Blood cells in the transport system
- Nerve cells in the nervous system
- Sperm cells in the reproductive system
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