Exam qs

• What does the Hardy-Weinberg principle predict? (3)

  • frequency of alleles
  • will stay constant over generations
  • providing no mutation / no selection / population large / mating at random / no migration
• Individuals in a population show phenotypic variation. Give two types of factor that cause this variation (2).

  • genetic factors
  • environmental factors
• What is allopatric speciation? (2)

  • New species form from different populations / gene pools;
  • In different areas/from isolated populations;
• Explain what is meant by the term phenotype (2)

  • expression / characteristic due to genetic constitution
  • due to the environment
• Explain how resistance to an antibiotic could become widespread in a bacterial population following a gene mutation conferring resistance in just one bacterium (5)

  • frequent use of antibiotic creates selection pressure / antibiotic kills bacteria
  • bacteria with mutation / resistance have selective advantage over others
  • survive to reproduce more than other types pass on advantageous allele
  • frequency of advantageous allele increases in subsequent generations
  • frequency of resistant type increases in subsequent generations