GCSE Biology (AQA)

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Sexual Reproduction

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Inheritance, Variation and Evolution Reproduction

Sexual Reproduction

1:49 Sexual and Asexual Reproduction
Spec 4.6.1.1 4.6.1.2
Previous Gametes Next Sexual Reproduction in Plants
  • Sexual reproduction occurs in eukaryotic organisms, including animals and plants.
  • Involves the fusion of male and female gametes.
  • In animals, sperm and egg cells join inside the female's reproductive system.
  • Fertilization occurs when sperm and egg cells join, restoring the normal chromosome number.
  • Sperm and egg cells each contain 23 chromosomes; after fertilization, the embryo has 46 chromosomes or 23 pairs.
  • Gametes are haploid cells, containing half the number of chromosomes of an adult cell.
  • When gametes combine, they form a diploid organism.
  • The specific chromosome numbers mentioned are unique to humans; different species have different numbers.
  • After fertilization, the new cell divides by mitosis, forming many new cells and eventually an embryo.
  • As the embryo develops, cells differentiate, transforming the embryo into a fetus, which grows in the mother's womb until birth.

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