CELL DIVISION
The nucleus is the site of RNA synthesis.
The nucleolus is the site of one type of RNA.
A fertilised cell divides to make two daughter cells. which are identical. These divide to make four identical cells, which divide again and again to make a ball of cells. Some cells in the ball grow and change shape to do a particular job. These specialized cells group together to form tissues.
Red and white blood cells form tissue which can carry oxygen and kill germs. This is called blood.
Substances pass in and out of cells as tiny particles known as molecules. Molecules are the smallest particles of a substance.
The movement of molecules is called diffusion.
Osmosis is a special kind of diffusion which occurs when a molecule has tiny holes which allow water molecules to pass through, but which prevent larger molecules, like sugar, from passing through.
Water moves from cell to cell in plants by osmosis. The cell membrane of a plant cell is semi-permeable.
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