This GCSE Biology quiz on making gametes (higher tier) explores meiosis, chromosome halving, and how sperm and egg cells are produced to create genetic variation.
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You can find more about this topic by visiting BBC Bitesize - Gamete production and fertilisation
This is the type of cell division that occurs to produce cells with the full number of chromosomes
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This type of cell division forms cells with only half of the genetic information
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In the first stages of meiosis, chromosomes make copies of themselves so (in humans) there are a total of 4 sets of chromosomes in the cell. These then separate, during two sets of cell division, into unpaired chromosomes so meiosis therefore creates 4 gametes.
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Before genetics and cell division was understood, scientists were completely puzzled about what made gametes different to other cells
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It is for that reason that variation of inherited features occurs.
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Different species have different chromosome numbers. For example, chimpanzees have 48 chromosomes in each body cell
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Each gamete contains half of the genetic material of the new individual
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Before any cell can divide, the chromosomes replicate and make an extra copy of the DNA. This maintains the chromosome number for the species. One arm of each chromosome duplicates an exact copy forming an X-shaped structure
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If every organism was identical to every other organism of the same species, it is possible that disease or a change in the environment would cause extinction
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At fertilisation, an egg containing 23 single chromosomes joins with the sperm also containing 23 single chromosomes to form a zygote with 46 chromosomes (23 pairs)
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