Week 3 Quiz

Question 1

Which events that occur in meiosis increase genetic diversity in sex cells?
* independent assortment
* genetic recombination
* horizontal gene transfer
* alternative splicing
* somatic mutation

Answer 1

• independent assortment
• genetic recombination

Question 2

Which of the following statements are correct?

• Expression of genes in one cell cannot affect the expression of genes in another cell of the same organism.
• Identical twins have the same genotype but differ in environmental effects on phenotype.
• Sometimes, gene expression is simply a cell’s response to the presence or absence of polyphyletic groups.
• Environmental conditions can influence gene expression within a cell by activating molecules that regulate the transcription or translation of genes.

Answer 2

• Identical twins have the same genotype but differ in environmental effects on phenotype.
• Environmental conditions can influence gene expression within a cell by activating molecules that regulate the transcription or translation of genes.

Question 3

How is the Hardy–Weinberg theorem used as a null hypothesis for evolution?
* Scientists use the theorem as a null hypothesis to determine if evolution by natural selection will drive an allele to fixation or extinction.
* Scientists accept the null hypothesis when the predicted and observed allele frequencies are statistically different and evolution has occurred.
* Scientists use the theorem as a null hypothesis for evolution because the theorem describes the conditions under which allele frequencies do not change.
* Scientists apply the theorem as a null hypothesis to estimate the degree of evolution caused by inbreeding of harmful alleles within a population.

Answer 3

• Scientists use the theorem as a null hypothesis for evolution because the theorem describes the conditions under which allele frequencies do not change.

Question 4

Suppose a population of organisms is in Hardy–Weinberg equilibrium. In the population, a gene has two alleles, B and b. If the frequency of B is 0.72 and the frequency of b is 0.28
what are the expected genotype frequencies of BB, Bb, and bb? Calculate each frequency to two decimal places.

Answer 4

BB = 0.72 x 0.72

Bb = 2 x 0.72 x 0.28

bb = 0.28 x 0.28