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B3 Revision:Reproduction, DNA (Key words: (Zygote (A fertilised egg, Ends…

- - - - Gametes are produced by meiosis
      - Produces four daughter cells which have half the normal number of chromosomes
      - Forms genetically different haploid gametes
      - In humans, meiosis only takes place in the reproductive organs(ovaries and testes)
    - - Produces genetic variation in the offspring, increasing the chances of survival in a change of environment, more likely to breed successfully and and pass on the genes for the characteristic (natural selection leading to evolution)
    - - Need to find and attract mates to reproduce
      - Takes more time and energy
      - Produces fewer offspring
  - - - Only needs 1 parent
      - Reproductive cycle quicker than sexual reproduction
      - Can produce lots of offspring very quickly
      - Can reproduce whenever conditions are favourable without having to wait for a mate
    - - No genetic variation between offspring so if environment changes and conditions become unfavourable, the population may be unable to cope
- - - - Held together by weak hydrogen bonds (A-T is 2 pairs and C-G is 3 pairs)