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 two factors contribute to the variation between organisms? 

  • The genes that individuals inherit 
  • That environment that individuals are exposed to
• A change in the DNA code is called a mutation.
• What factor(s) are involved in determining body mass?

  Both genetic factors and environmental factors

  Our genes influence our size and mass, but environmental factors, such as how much we eat, will also impact it.
• Which of the following are determined entirely by genetic factors?

  Biological sex (male or female)

  Natural eye colour
• A change in the genetical material of an organism is called a mutation.
• statement about mutations?

  They generally have no effect, but are occasionally harmful, and very occasionally advantageous 
• What does the phrase '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. In some cases this may result in the formation of a new species.
• Who is credited with developing and proposing the theory of evolution?

  Charles Darwin
• Which of the following provide evidence for the theory of evolution?

  • Fossil records
  • The spread of antibiotic resistance
• Describe a series of events that might result in zebras evolving to run more quickly.

  • There is variation among the zebra population so that some can run faster than others 
  • A mutation arises that allows some zebras to run faster
  • Those zebras that can run fastest are more likely to survive and are therefore more likely to reproduce and pass on their advantageous alleles 
  • This repeats over multiple generations 
  • So the advantageous allele spreads throughout the population, until the species has 'evolved' to run faster
• Speciation is the evolutionary process by which populations evolve to become distinct species.