Variation and Evolution

• What is variation in organisms?

  Differences in the characteristics of organisms
• What causes genetic variation within a population?

  Differences in the genes individuals inherit
• How extensive is genetic variation usually?

  It is usually extensive
• Give an example of genetic variation.

  Eye colour
• What causes mutations in genes?

  Mutations continuously occur
• What is the effect of most mutations on phenotype?

  Most mutations have no effect
• What is the effect of some mutations on phenotype?

  Some mutations cause slight changes
• What is the result of very few mutations?

  They can create a new phenotype
• What causes environmental variation?

  Differences in conditions during development
• Give an example of environmental variation.

  Leaf colour
• What causes variation in most characteristics?

  Both genetics and the environment
• Give an example of a characteristic influenced by both genetics and environment.

  Plant height
• Who proposed the theory of evolution by natural selection?

  Charles Darwin
• What does Darwin's theory state about today's species?

  They evolved from simple life forms
• How long ago did simple life forms start to develop?

  Over three billion years ago
• What does limited resources lead to among organisms?

  Competition among organisms
• What characteristics help organisms survive in their environment?

  Most suitable characteristics for the environment
• What happens to organisms with beneficial characteristics?

  They are more likely to survive and breed
• How are beneficial characteristics passed on in a population?

  They gradually become more common
• What can happen to two populations of a species over time?

  They can evolve in different ways
• What defines two populations as separate species?

  They can no longer produce fertile offspring
• What are the key concepts of natural selection?

  • Organisms compete for limited resources
  • Variation exists within species
  • Beneficial traits enhance survival and reproduction
  • Traits are passed to offspring
  • Over time, beneficial traits become common