genetics chapter 6 practice problems

Why is knowledge of population genetics clinically important?

B. It helps estimate the risk of certain conditions based on ancestral origins.

A small group migrates from a larger population and establishes a new community with only part of the original population's genetic variation. Which concept best describes this?

C. Founder effect

Researchers observe an association between ancestry and disease, but an environmental factor related to both may explain the association. What is the main concern?

B. The environmental factor may create a spurious association.

Two individuals share an allele because they inherited it from a recent common ancestor. What is this called?

C. Identity by descent

Which of the following is an assumption of Hardy-Weinberg equilibrium?

B. Individuals mate randomly.

In a population, allele A has frequency p = 0.7 and allele a has frequency q = 0.3. Assuming Hardy-Weinberg equilibrium, what is the expected frequency of genotype Aa?

C. 0.42 (2pq = 2 × 0.7 × 0.3)

If allele a has frequency q = 0.2, what is the expected frequency of genotype aa at Hardy-Weinberg equilibrium?

A. 0.04 (q² = 0.2²)

Researchers compare the frequency of alleles in affected individuals with the frequency in unaffected controls from the same population. Which approach are they using?

B. Genome-wide association study (GWAS)

Researchers follow a disease through several generations of a family to see whether it is repeatedly inherited with a particular genomic region. Which approach is this?

B. Linkage analysis

Two loci are so close together that crossovers between them never occur. What is expected?

B. No recombination is expected, and the loci are transmitted together.

When two loci are far apart and at least one crossover occurs between them, what is expected on average?

C. Recombinant and non-recombinant genotypes occur in equal proportions.

A linkage analysis produces a LOD score of 3.2. How should this result be interpreted according to the lecture?

C. Strong evidence of linkage

Which LOD score provides strong evidence against linkage?

D. −2.5 (a LOD score of −2 or lower)

In genetic linkage analysis, what does phase describe?

B. Whether alleles are on the same chromosome (cis) or opposite homologous chromosomes (trans)

Which method is designed to identify the specific causative variant by examining variation across the genome or coding sequences?

C. Direct genome-wide sequencing