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The Hardy-Weinberg Principle quiz #3

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  • How do you calculate the expected genotype frequencies in a population if the frequency of allele A (p) is 0.3 and the frequency of allele a (q) is 0.7?
    Use the Hardy-Weinberg equation: p² = 0.09 (AA), 2pq = 0.42 (Aa), and q² = 0.49 (aa).
  • How can you determine if a population is in Hardy-Weinberg equilibrium using observed genotype counts?
    Calculate allele frequencies from the observed counts, use them to predict expected genotype frequencies with the Hardy-Weinberg equation, convert these to expected counts, and compare to the observed counts. If they match, the population is in equilibrium; if not, it is not.
  • What is the Hardy-Weinberg equation used for in population genetics?
    It is used to predict genotype frequencies in a diploid population with two alleles, assuming random mating and no evolution.
  • What are the two main assumptions required for a population to be in Hardy-Weinberg equilibrium?
    The population must have random mating and no changes to allele frequencies (no evolution occurring).
  • How do you calculate the expected genotype frequencies if the frequency of allele A (p) is 0.3 and allele a (q) is 0.7?
    Use the Hardy-Weinberg equation: p² = 0.09 (AA), 2pq = 0.42 (Aa), and q² = 0.49 (aa).
  • How can you determine allele frequencies from observed genotype counts in a population?
    Calculate the number of each allele from the genotype counts, divide by the total number of alleles, and use p + q = 1 to find both allele frequencies.
  • What steps do you follow to test if a population is in Hardy-Weinberg equilibrium using observed genotype counts?
    Calculate allele frequencies from observed counts, use them to predict expected genotype frequencies, convert these to expected counts, and compare to the observed counts; if they match, the population is in equilibrium.
  • If 1% of a population is homozygous recessive (aa), how do you find the frequency of the recessive allele (q)?
    Set q² = 0.01, take the square root to get q = 0.1.
  • How do you calculate the frequency of heterozygotes (Aa) in a population using the Hardy-Weinberg equation?
    Use the formula 2pq, where p and q are the frequencies of the two alleles.
  • Why might a population not match Hardy-Weinberg expectations, and what could this indicate?
    If observed and expected genotype frequencies differ, it suggests that at least one assumption (random mating or no evolution) is violated, indicating possible non-random mating or evolutionary forces at work.
  • What does it mean for a population to be in Hardy-Weinberg equilibrium, and what happens to allele and genotype frequencies under these conditions?
    When a population is in Hardy-Weinberg equilibrium, allele and genotype frequencies remain constant from generation to generation. This occurs under the assumptions of random mating and no evolution (no changes in allele frequency). The Hardy-Weinberg equation (p² + 2pq + q² = 1) can be used to predict genotype frequencies, and the population serves as a null model for testing evolutionary changes.
  • What are the implications for a population that matches the predictions of the Hardy-Weinberg equation?
    If a population matches the predictions of the Hardy-Weinberg equation, it indicates that the population is not evolving for the gene in question. This means allele and genotype frequencies are stable, and the population is experiencing random mating with no evolutionary forces (such as selection, mutation, migration, or genetic drift) acting on the gene.