Cards (14)

  • What was Darwin's theory of natural selection?
    If an organism changes during it's life in order to adapt to it's environment, those changes are passed onto it's offspring
  • What happens during natural selection?
    1. A population has genetic variation and mutations lead to new alleles.
    2. A change in the environment leads to a change in the selection pressures on the population
    3. An allele that was of no advantage becomes favourable
    4. Organisms with the allele are more likely to survive, reproduce and pass on the advantageous allele to their offspring
    5. The offspring are more likely to have the advantageous allele so its frequency increases in the population
  • Which main words need to be included in an answer on Natural Selection?
    1. mutation/ variation
    2. advantage (selection pressure)
    3. survival
    4. reproduction
    5. greater allele frequency
  • What is selection pressure?
    Environmental factors that influence the survival of individuals, leading to certain traits becoming more or less common in a population over time.
  • What causes speciation?
    Natural selection- leads to the formation of a new species
  • How can speciation occur?
    Through species isolation
  • What does speciation provide evidence for?
    Natural selection
  • Which factors lead to sexual reproduction of fertile offspring?
    1. Looks ie colourful feathers
    2. Behaviour ie bird songs
    3. Time/ seasonality ie pollination season
    4. Anatomy
    5. Gamete compatibility
    6. Hybrid inviability
    7. Hybrid being fertile
  • What can cause speciation?
    Reproductive isolation due to geographical barriers/ changes
  • How did the experiment result in speciation (EQ)?

    The population was split up and geographically separated, leading to no gene flow between the two groups.
    • Mutations/ gene variation led to a change in the allele frequencies between the populations
    • The species became reproductively isolated and their offspring could no longer breed to make fertile offspring
  • Why may populations not be able to breed together?
    • Mechanical changes/ Physical incompatibility
    • Seasonal changes
    • Behavioural changes
  • What is a species?

    A group of organisms that can breed to produce fertile offspring
  • What is the heterozygozity index?

    A measure of genetic diversity within a population.
  • What is species richness?

    The different number of species in a habitat