Question 1

Spontaneous mutation is the result of

Accepted Answer

Spontaneous mutations occur naturally without any external influence, often due to errors in DNA replication or natural chemical changes in DNA.

Question 2

What effect does natural selection have on population variation?

Accepted Answer

Natural selection favors certain traits within a population, leading to a decrease in variation as those traits become more common. This is because individuals with favorable traits are more likely to survive and produce offspring with those traits, while individuals with less favorable traits are less likely to survive and pass on their genes. Over time, this process can lead to a reduction in diversity within a population.

Question 3

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

Accepted Answer

The Hardy-Weinberg equilibrium assumes random mating and no other evolutionary forces acting on the population. In this case, the gene frequencies have changed from one generation to the next, which suggests that either random mating is not occurring or that other evolutionary forces are at play.

Question 4

Patrilocal societies are expected to display

Accepted Answer

In patrilocal societies, women move to live with their husband's family, leading to greater mtDNA diversity as women from different lineages mix, while men remain in their birthplace, resulting in less Y chromosome diversity.

Question 5

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

Accepted Answer

Trisomy 21 is more commonly known as Down syndrome.

Question 6

Transposable elements are DNA sequences that

Accepted Answer

Transposable elements are DNA sequences that have the ability to copy themselves and move to new locations within the genome. They do not necessarily contain point mutations or code for proteins, and they can occur on any chromosome, not just the X and Y. Therefore, the best choice is D - can copy themselves into entirely new areas of the chromosomes.

Question 7

Frameshift mutations are more likely to have an impact at the phenotypic level because they

Accepted Answer

Frameshift mutations alter the reading frame of the genetic code, often leading to a completely nonfunctional protein due to the introduction of premature stop codons or extensive missense mutations.

Question 8

Over a period of two generations, the frequency of green dung beetles in a population shifts from 75% to 71%, while the frequency of brown dung beetles within this population shifts from 25% to 29%.This is an example of

Accepted Answer

Microevolution refers to small-scale changes in allele frequencies within a population over a short period, such as a few generations. The change in frequency of green and brown dung beetles is an example of microevolution.

Question 9

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

Accepted Answer

The Hardy-Weinberg equilibrium assumes random mating, no mutations, large population size, no migration, and no selection. The unchanged genotype frequencies suggest these conditions are met, particularly random mating.

Question 10

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 11

You are reading a scientific article about cheetahs that have stripes instead of spots.The article refers to this as a genetic mutation.Though they have no negative impact on the cheetahs' fitness, why are the stripes nevertheless considered a genetic mutation?

Accepted Answer

Mutations are changes in the DNA sequence, and they can be neutral, beneficial, or harmful. In this case, the stripes are a neutral mutation with no impact on fitness.

Question 12

Familial hypercholesterolemia, an autosomal dominant disease, is five times more frequent in the Afrikaner population of South Africa than in the original population of Europe from which the ancestors to the Afrikaners emigrated.This represents an example of

Accepted Answer

The founder effect occurs when a small group of individuals becomes isolated from a larger population, leading to a higher frequency of certain genetic traits in the new population, as seen in the Afrikaner population with familial hypercholesterolemia.

Question 13

The best-documented case of industrial melanism involves

Accepted Answer

The case of industrial melanism in peppered moths is well-documented, showing how pollution affected their coloration and survival.

Question 14

Fitness trade-off refers to selection favoring which genotype?

Accepted Answer

Fitness trade-off often refers to the advantage of heterozygous genotypes in certain environments, where they may have higher fitness than either homozygous genotype.

Question 15

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, the percentage of genotypes was found to be as follows:

Accepted Answer

The answer of In a classroom taste test for PTC...

Question 16

The absence of the A and B blood type alleles in Native American populations is a result of

Accepted Answer

The founder effect occurs when a small group of individuals becomes isolated from a larger population, leading to a reduced genetic diversity. Native American populations likely descended from a small group of ancestors who did not carry the A and B blood type alleles, resulting in their absence in these populations.

Question 17

The evolution of the modern horse with a single hoof on each limb from a dog-sized ancestral species with multiple digits is an example of

Accepted Answer

The evolution of the modern horse from a multi-digit ancestor to a single-hoofed species is a large-scale evolutionary change over a long period, which is an example of macroevolution.

Question 18

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

Sickle-cell anemia is caused by inheriting two recessive alleles, one from each parent, making the individual homozygous recessive.

Question 19

A random change in allele frequencies over time is known as

Accepted Answer

Genetic drift is a random change in allele frequencies over time. It can occur due to a number of factors, including natural disasters, population bottlenecks, and founder effects.

Question 20

Which of the following is a good definition of natural selection?

Accepted Answer

Natural selection is the process where certain alleles become more common in a population due to nonrandom elimination, as individuals with advantageous traits are more likely to survive and reproduce.

Quiz 4: Genes and Their Evolution: Population Genetics