Question 1

Explain how the founder effect can lead to a descendant population that differs greatly from its parent population over a relatively short period of time.

Accepted Answer

The answer of Explain how the founder effect can lead...

Question 2

An individual who displays the disease sickle-cell anemia must have inherited the deleterious allele from both phenotypically normal parents.This individual is therefore

Accepted Answer

A person with sickle-cell anemia must inherit two copies of the recessive allele, one from each parent, making them homozygous recessive for this trait.

Question 3

A study of Darwin's finches after a long period of drought found that all species of finch on one of the islands developed wide beaks in order to break open seeds.The type of evolution that leads to this phenotype distribution is

Accepted Answer

Directional selection occurs when one extreme phenotype is favored over others, leading to a shift in the population's trait distribution, such as the development of wide beaks in finches to adapt to environmental changes.

Question 4

A genetic study conducted over multiple generations found that the frequency of genotypes in the first generation were AA: 0.36, Aa: 0.48, aa: 0.16.In the second generation, genotype frequencies shifted to AA: 0.16, Aa: 0.48, aa: 0.36.According to the Hardy-Weinberg equilibrium, we can assume

Accepted Answer

The Hardy-Weinberg equilibrium predicts that allele and genotype frequencies will remain constant over generations in the absence of evolutionary forces such as mutation, selection, gene flow, and nonrandom mating. Since the genotype frequencies have shifted between the first and second generation, we can rule out option A. Option B suggests that gene flow may have played a role in the change, but we cannot confirm this without further evidence. Option C suggests that there was nonrandom mating, which could also have affected the genotype frequencies, but we cannot confirm this without further information. Therefore, the best option is D, which suggests that either gene flow or nonrandom mating, or both, could have caused the change in genotype frequencies.

Question 5

Familial hypercholesterolemia, an autosomal dominant disease, is five times more frequent in the Afrikaner population of South Africa than in the population of Europe or the United States.This represents an example of

Accepted Answer

The higher frequency of familial hypercholesterolemia in the Afrikaner population of South Africa is an example of the founder effect, which occurs when a small group of individuals break off from a larger population and establish a new population with limited genetic diversity. Since the Afrikaner population is descended primarily from Dutch and German settlers, it is likely that a high number of individuals in the founding group carried the autosomal dominant gene for familial hypercholesterolemia, leading to a greater frequency of the disease in this population. Natural selection, kin selection, and bottleneck do not accurately describe this phenomenon.

Question 6

Why is a frameshift mutation far more likely to lead to a defective protein compared with a point mutation?

Accepted Answer

The answer of Why is a frameshift mutation far more...

Question 7

In a classroom taste-test for PTC, the genotype frequency was determined to be P = 0.35 and Q = 0.65.After applying the Hardy-Weinberg equation, which of the following was found to be the percentage of genotypes?

Accepted Answer

The answer of In a classroom taste-test for PTC, the...

Question 8

Why is the incidence of sickle-cell anemia an excellent example of a "balanced polymorphism," in which two or more alleles are maintained by natural selection in a population?

Accepted Answer

The answer of Why is the incidence of sickle-cell anemia...

Question 9

Why is the peppered moth an excellent example of directional selection?

Accepted Answer

The answer of Why is the peppered moth an excellent...

Question 10

The mutation known as trisomy 21, in which an extra copy of chromosome 21 is present, is more commonly known as

Accepted Answer

Trisomy 21, also known as Down syndrome, is a genetic condition in which an individual has an extra copy of chromosome 21. Turner syndrome (A) results from a missing or partially missing X chromosome in females. Klinefelter's syndrome (C) is caused by an extra X chromosome in males. Williams syndrome (D) is a genetic condition caused by a deletion of genetic material on chromosome 7.

Question 11

A genetic study conducted over two generations found that the frequency of genotypes in the first generation were AA: 0.36, Aa: 0.48, aa: 0.16.In the second generation, genotype frequencies remained the same.According to the Hardy-Weinberg equilibrium, we can assume

Accepted Answer

According to the Hardy-Weinberg equilibrium, if the frequencies of genotypes remain constant, then mating within the population is random and no other factors (such as mutations or assortative mating) are at play. Therefore, the best choice is C that states mating in this population is random.

Quiz 4: Genes and Their Evolution: Population Genetics