6.1.2. Patterns of Inheritance

• What is the definition of phenotype?

  The expression of an organism's genetic constitution
• How does phenotype relate to the environment?

  It combines genetic constitution with environmental interaction
• How does meiosis contribute to genetic variation?

  Through random arrangement of chromosomes and crossing over
• What role does random fertilization play in genetic variation?

  It combines different DNA from haploid gametes
• What is monogenic inheritance?

  One phenotypic characteristic controlled by a single gene
• What is dihybrid inheritance?

  Two phenotypic characteristics determined by different genes
• What is sex-linkage?

  Allele located on a sex chromosome
• What are multiple alleles?

  A gene with more than two alleles
• What are codominant alleles?

  Two dominant alleles contributing to the phenotype
• What is autosomal linkage?

  Genes located on the same non-sex chromosome
• What is epistasis?

  Interaction where one gene masks another
• What is the chi-squared test?

  A statistical test for observed vs expected data
• How is a chi-squared test performed?

  Compare calculated number to critical value
• How do genes influence variation?

  • Discontinuous variation: One gene (monogenic)
  • Continuous variation: More than one gene (polygenic)
• What is stabilising selection?

  Selection favoring individuals closest to the mean
• What is directional selection?

  Selection favoring phenotypes suited to new conditions
• What is genetic drift?

  Change in allele frequencies due to chance
• What is a genetic bottleneck?

  Catastrophic event reducing population size
• What is the founder effect?

  Isolation of a small number of individuals
• What is the Hardy-Weinberg principle?

  Estimates allele frequency in a population
• What does the Hardy-Weinberg equation for allele frequency state?

  p + q = 1, where p is dominant allele
• What does the Hardy-Weinberg equation for genotype frequency state?

  p² + 2pq + q² = 1 for genotype frequencies
• What is speciation?

  Population split leading to separate species
• What is allopatric speciation?

  Speciation due to a physical barrier
• What is sympatric speciation?

  Speciation due to non-physical barriers
• What is artificial selection?

  Humans breed organisms for desired traits
• Why is it important to keep genetic material in selective breeding?

  To reintroduce traits bred out accidentally
• What are ethical issues around artificial selection?

  • Anatomical changes causing health issues
  • Higher disease susceptibility in plants and animals