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6.1.2: Meiosis

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Cells in reproductive organs divide by meiosis to form gametes.

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Before meiosis, copies of the genetic information are made.

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The cell divides twice to form four gametes, each with a single set of chromosomes.

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All gametes are genetically different from each other.

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Gametes join at fertilisation to restore the normal number of chromosomes.

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The new cell divides by mitosis, the number of cells increases, and cells differentiate as the embryo develops.

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Knowledge of the stages of meiosis is not required.

Common exam mistakes

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Do not use human chromosome numbers automatically; use the chromosome numbers given in the question.

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Meiosis forms gametes with half the normal chromosome number, so fertilisation can restore the normal number.

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Do not say meiosis happens "in gametes"; meiosis produces gametes.

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If the question asks why chromosome number changes, do not give a long mitosis comparison instead.

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