Fertilisation

• How does fertilisation occur

  • sperm + egg cell fuses together to produce zygote (fertilised egg)
  • each gamete produces 23 chromosomes
  • zygote undergoes mitosis to develop into embryo
  • inherits features from both parents
• what are the advantages of asexual reproduction

  • population can increase rapidly when conditions are favourable
  • only needs 1 parent
  • more time + energy efficient (dont need mate)
  • faster than sexual reproduction
• what are the advantages of sexual reproduction

  • variation in offspring
  • species can adapt to new environments
  • disease less likely to affect whole population
  • humans can speed up natural selection through selective breeding -> increase population
• what are the disadvantages of asexual reproduction

  • no variation
  • species may only suit one type of habitat -> mass extinction
  • disease can affect all individuals in a population
• what are the disadvantages of sexual reproduction

  • time + energy needed to find a mate
  • not possible for isolated individual
• what's sexual reproduction

  • involves joining of 2 sex cells during fertilisation
  • mixing of 2 parents -> genetic variation
  • eg. pollen + egg cells in plants
• what's asexual reproduction

  • reproduction by a single parent
  • offspring are clones