Variation & Evolution

• What does the term ‘phenotype‘ mean?


  The observable characteristics of an organism.
• Differences in the characteristics of individuals within a population is called variation.
• Which 2 factors contribute to the variation between organisms?

  Genes that individual inherits.

  Environment individuals are exposed to.
• A change in the DNA code is called a mutation.
• What factor(s) are involved in determining body mass?

  Genetic factors

  Environmental factors
• What can be determined entirely by genetic factors?

  Biological sex

  Natural eye colour
• What can be determined by environmental factors?

  Skin colour (amount of sun time)

  Height (eat or sleep more)
• A change in the genetic material of an organism is called a..

  Mutation
• Mutations..

  Generally have no effect, but are occasionally harmful, and very occasionally advantageous.
• What does ‘survival of the fittest’ mean?

  The individuals with the most favourable characteristics are most likely to survive.
• Evolution is the process by which the inherited characteristics of a population change over time due to natural selection. Can result in formation of new species.
• Who is credited with developing and proposing the theory of evolution?

  Charles Darwin
• Evidence for the theory of evolution:

  Fossil records

  The spread of antibiotic resistance
• Describe a series of events that may result in zebras evolving to run more quickly?

  Variation so some can run faster.

  A mutation arises that allows some zebras to run faster.

  Those zebras that can run fastest more likely to survive.

  And are therefore more likely to reproduce and pass on advantageous alleles.

  Repeats over generations.

  Advantageous allele spreads through population, until species ‘evolved‘ to run faster.
• Speciation is the evolutionary process by which populations evolve to become distinct species.