Variation

• What is a key idea in biology discussed in relation to genetics?

  Variation
• What is defined as all the differences in the characteristics of individuals in a population?

  Variation
• How many main causes of variation are mentioned within any population?

  Three
• What is the first cause of variation mentioned in the study material?

  The alleles individuals have inherited
• What kind of cause is the alleles that individuals have inherited?

  Genetic
• What is another cause of variation besides inherited alleles?

  The environment
• What is the third cause of variation discussed?

  A combination of genes and environment
• Why is diet mentioned in the context of height variation?

  Sufficient calcium is needed for bone development
• What is responsible for the massive amount of genetic variation in any population of a species?

  Mutations
• What are mutations described as?

  Random changes to DNA
• What effect do most mutations have on the phenotype?

  No effect at all
• What happens if someone has alleles for tallness and a suitable diet?

  They may lead to tallness
• What does the study material say about how many mutations determine phenotype?

  A small number
• What key idea about mutation is crucial to understand?

  Very rarely can lead to a new phenotype
• What can a new phenotype lead to if the environment changes?

  A rapid change in the species
• In what decade did a virus kill 99% of wild rabbits in the UK?

  1950s
• What is the status of the beneficial phenotype in the UK rabbit population after the virus outbreak?

  It is widespread
• What is a phenotype?

  The observable characteristics of an organism