Chapter 13: Variation & Evolution

• What is variation?

  differences in the characteristics of individuals in a population
• What can cause variation?

  genetic causes, environmental causes, and a combination of genes and the environment
• How do new phenotype variants occur?

  mutations
• What is selective breeding?

  breeding plants and animals for particular characteristics
• Describe the process of selective breeding (4)

  1. choose parents with the desired characteristic
  2. breed them together
  3. choose offspring with the desired characteristic and breed again
  4. continue over many generations until all offspring show the desired characteristic
• What are the consequences of inbreeding?

  inherited defects and disease
• What is genetic engineering?

  modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
• How have plant crops been genetically engineered?

  to be resistant to diseases/herbicides/pesticides, to produce bigger fruits, to give higher yields
• How have bacteria been genetically engineered?

  to produce useful substances, such as human insulin to treat diabetes
• What are enzymes used for in genetic engineering?

  cut out the required gene
• What is used to transfer the required gene into the new cell in genetic engineering?

  vector (e.g., bacterial plasmid or virus)