Sexual and asexual reproduction

• Sexual reproduction

  Genetic information from two organisms (a father and a mother) is combined to produce offspring which are genetically different to either parent
• Components of sexual reproduction

  • Mother
  • Father
  • Gametes
  • Fertilised egg
  • Embryo
• Gametes


  • Produced by the mother and father
  • Contain half the number of chromosomes of normal cells
  • Fused together to produce a fertilised egg
• Fertilisation

  A male gamete fuses with a female gamete to produce a fertilised egg
• Fertilised egg

  Ends up with the full set of chromosomes
• Embryo development

  Undergoes cell division (by mitosis) and develops into an embryo
• The embryo inherits characteristics from both parents as it's received a mixture of chromosomes (and therefore genes)
• Asexual reproduction

  Offspring are genetic copies of the parent
• Asexual reproduction


  An ordinary cell makes a new cell by dividing in two
• New cell

  Has exactly the same genetic information (i.e. genes) as the parent cell
• Clones

  Genetic copies of the parent
• Asexual reproduction

  • Bacteria
  • Some plants
  • Some animals
• Reproducing is very important to all organisms - it's how they pass on their genes
• Methods of reproduction

  • Sexual reproduction
  • Asexual reproduction
  • Both sexual and asexual reproduction
• Asexual reproduction advantages

  • Asexual reproduction can produce lots of offspring very quickly
  • Only one parent is needed, allowing reproduction whenever conditions are favourable without waiting for a mate
• Organisms reproducing asexually

  • Bacteria, such as E. coli
  • Aphids during summer when there is plenty of food
• Advantages of sexual reproduction

  • Creates genetic variation within the population, enabling survival in changing environmental conditions and leading to evolution
• Disadvantages of asexual reproduction

  • No genetic variation between offspring, making the whole population vulnerable to environmental changes
• Disease affecting banana plants

  • Black Sigatoka affecting banana plants that reproduce asexually
• Disadvantages of sexual reproduction

  • Takes more time and energy, resulting in fewer offspring produced in a lifetime
  • Requires two parents, which can be challenging if individuals are isolated
• Challenges of finding mates

  • Male bowerbirds building attractive structures and dancing for females
  • Male polar bears having to walk long distances to find a mate
• Asexual reproduction - bacteria's answer to life in the fast lane...