Topic 3 - GENETICS

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  • Created by: Aamna.M
  • Created on: 14-05-17 12:13

3.1b - asexual reproduction

Advantages

  • Asexual reproduction can produce lots of offspring very fast can produce offspring very quickly because the reproductive cycle (the time it takes to produce independant offspring) is so fast. 
  • This can allow organisms to colonise a new area rapidly - large colonies can out compete other organisms for resources
  • Only one parent is needed - this means that organisms can reproduce whenever conditions are favourable, without having to wait for a mate
  • Therefore they can also conserve resources as they don't need to find a partner.

Disadvantages

  • There is no genetic variation between offspring in the population - vunerable to disease
  • So, if the environment changes and conditions become unfavourable, the whole population may be affected
  • Unfavourable mutations are passed on to future generations
  • No competiton for breeding so increased competition for resources as population booms

3.2b - sexual reproduction

Advantages

  • sexual reproduction creates genetic variation within the population, which means that different individuals have different characteristics.
  • This means that if the environmental conditions change, it's more likely that some individuals in the population will have the characteristics to survive the change
  • This can lead to natural selection and evolution as species become better adapted to their new environment

Disadvantages

  • It takes more time and energy than as.rep. so offpring produce fewer offspring in their lifetime
  • Two parents are needed for sexual reproduction. This can be a problem if the individuals are isolated.

3.3b - The role of Meiosis

  • ONLY takes place in the reproductive organs.
  • Cells divide here to make gametes.
  • The gametes only contain one chromosome from each pair (haploid).
  • One gamete from each of your parents fuses to make a zygote.
  • It doesn't produce identical cells

DIVISION 1

  •  Before division the cell duplicates it's DNA.
  • The chromosomes line up in pairs in the centre of the cell; one came from

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