Question 1

Which statement about evolution is false?

Accepted Answer

This statement is false because evolution occurs at the population level, not the individual level. An individual organism may have traits that make it better suited to survive and reproduce, but that does not necessarily mean those traits will become more common in the population over time.

Question 2

A1 and A2 are different forms of the same gene.These are thus different

Accepted Answer

A1 and A2 are different forms of the same gene, therefore they are different alleles of a single gene.

Question 3

Which is usually the easiest to examine without specialized equipment?

Accepted Answer

Phenotypes are physical or observable traits of an organism, such as hair color or height, and can be examined without the need for specialized equipment. In contrast, examining alleles and genotypes often requires genetic analysis, and examining gene pools requires an understanding of population genetics.

Question 4

Females preferring male bowerbirds with large bowers is an example of _______ selection.

Accepted Answer

The preference of females for males with larger bowers is an example of intersexual selection, where individuals of one sex choose mates based on their physical or behavioral characteristics. This is in contrast to intrasexual selection, where individuals of the same sex compete for access to mating opportunities. Purifying, stabilizing, and disruptive selection refer to other types of natural selection that act on the overall genetic makeup of a population, rather than on individual mate choice.

Question 5

The generation of broccoli from the ancestral Brassica oletracea was achieved by _______ selection for specific features of the _______.

Accepted Answer

Broccoli was developed from the wild cabbage Brassica oleracea through artificial selection, specifically targeting the enlargement of stems and flowers. This selective breeding process was carried out by humans to enhance certain desirable traits.

Question 6

High-throughput sequencing reveals that 30 new mutations have occurred in the coding regions of genes in an individual lizard.If the coding regions of this lizard comprise 150 million nucleotides per haploid genome, what is the mutation rate per nucleotide?

Accepted Answer

The answer of High-throughput sequencing reveals that 30 new mutations...

Question 7

Small populations are _______ likely to be near Hardy-Weinberg equilibrium than large populations, because genetic drift is _______ important in small populations.

Accepted Answer

Small populations are more likely to be affected by genetic drift because there are fewer individuals available to contribute to the gene pool. As a result, random fluctuations in allele frequencies are more likely to occur, leading to deviations from Hardy-Weinberg equilibrium. In contrast, large populations are less likely to experience genetic drift because there are more individuals available to contribute to the gene pool, which can help to buffer against random changes in allele frequencies. Therefore, small populations are less likely to be near Hardy-Weinberg equilibrium than large populations.

Question 8

A genetic locus has two alleles.One has a frequency of 0.12; the other has a frequency of _______.

Accepted Answer

The frequency of the two alleles must add up to 1, so the other allele must have a frequency of 1 - 0.12 = 0.88.

Question 9

What is the primary distinction between artificial selection and natural selection?

Accepted Answer

The primary distinction between artificial selection and natural selection is that artificial selection involves purpose, whereas natural selection does not. Artificial selection is performed by humans with the intention of producing and selecting for specific traits, while natural selection occurs in nature based on an organism's ability to survive and reproduce in their environment.

Question 10

Male mallards fighting with one another for access to females is an example of _______ selection.

Accepted Answer

Intrasexual selection involves competition between members of the same sex for access to the opposite sex, and male mallards fighting with one another for access to females falls under this category.

Question 11

Which statement about mutations is true?

Accepted Answer

Environmental changes can create new environments or alter existing ones, which can make previously neutral mutations advantageous. This is one possible way that mutations can lead to genetic changes within a population over time. The other statements are false. Most mutations are neutral or deleterious, rather than advantageous, and mutations do not occur in response to an organism's needs. Mutations can increase genetic variation within a population rather than decrease it.

Question 12

Suppose males of a bird species have much more colorful plumage than the females and that the intensity of red color varies in males.Which would be the best evidence that intrasexual selection was occurring?

Accepted Answer

Intrasexual selection involves competition among the same sex for access to mates. If brighter red males outcompete paler males for access to females, it indicates intrasexual selection.

Question 13

Suppose a hard frost in southern Florida wipes out nearly all of a population of plants.Even though the plant population recovers in numbers after a couple of decades, the genetic variation within that population remains much reduced.Which is the most likely cause of the diminished genetic variation?

Accepted Answer

The scenario described fits the definition of a population bottleneck, where a severe reduction in population size can lead to decreased genetic variation due to the loss of alleles. The loss of variation is not likely due to founder effect, which occurs when a new population is established by a few individuals with lower diversity than the original population. Purifying selection removes deleterious mutations but does not necessarily lead to decreased genetic variation. Gene flow, the movement of genes between populations, can actually increase genetic variation. Muller's ratchet refers to the gradual accumulation of deleterious mutations in asexual populations, and is not relevant in this scenario where the population size eventually recovers.

Question 14

In a population of hamsters, some individuals have the nucleotide G at a locus and some have the nucleotide A.Stating that an individual has copies of both G and A characterizes that individual's _______, and that individual is a _______.

Accepted Answer

The term "genotype" refers to an individual's genetic makeup at a specific locus, while "heterozygote" describes an individual who has two different alleles at a particular locus (in this case, G and A). Therefore, stating that an individual has both G and A nucleotides characterizes their genotype, and they are a heterozygote. The term "gene pool" refers to the total collection of alleles present in a population, so choices A and B are incorrect. The terms "allele frequency" and "homozygote" are not relevant to the given scenario, so choices D and E are incorrect.

Question 15

There are three isolated populations of garter snakes: population A has had a constant population size of about 50,000, population B has had a constant population size of about 12,000, and population C has had a constant population size of about 2,000.We would expect to see the greatest fluctuations of allele frequencies in population _______ because this population would experience the _______ genetic drift.

Accepted Answer

According to the Hardy-Weinberg principle, genetic drift occurs more dramatically in smaller populations. Population C has the smallest population size, so it would experience the most genetic drift and fluctuations in allele frequencies.

Question 16

Genetically identical roundworms are raised in two different environments.In the warmer environment, the worms are shorter than they are in the cooler one.What can we infer from this observation?

Accepted Answer

The fact that genetically identical roundworms raised in different environments have different phenotypes (shorter in warmer environment) implies that different phenotypes can arise from the same genotype. This could be due to the expression of certain genes being influenced by environmental factors, which can result in different physical characteristics even in genetically identical individuals.

Question 17

A windstorm transports a gravid fly to an island.Having only a small subset of the genetic variation in the mainland population, the offspring of this fly are somewhat different from the mainland population.This is an example of

Accepted Answer

The scenario described is an example of the founder effect, which occurs when a small subset of a population colonizes a new area and the genetic variation of that population differs from the original population due to chance. The fly being transported by a windstorm and establishing a new population on an island is consistent with this situation. The fact that the new population has only a small subset of the genetic variation in the mainland population further supports the idea of a founder effect.

Question 18

It may be that red hair evolved in Neanderthals and then was introduced into human populations via interbreeding.If this is so, this would be an example of

Accepted Answer

Gene flow refers to the movement of genes from one population to another. In the context of the question, the interbreeding between Neanderthals and humans allowed for the introduction of the gene for red hair into human populations.

Question 19

In a population of pitcher plants, 200 individuals are sampled for variation at a locus.Sixteen are heterozygous for the X1 allele, and four are homozygous for it.What is the frequency of the X1 allele?

Accepted Answer

The answer of In a population of pitcher plants, 200...

Question 20

Three different alleles (c1, c2, and c3) at the c locus exist in a hypothetical population of juniper trees.If the frequency of c1 is 0.3, what can be said about the frequency of c2?

Accepted Answer

The frequency of c2 cannot be determined with the information given because we also need to know the frequency of c3 to calculate the frequency of c2. The sum of the frequencies of all alleles at a locus must equal 1, but without the frequency of the third allele, c3, we cannot determine the frequency of c2.

Quiz 20: Mechanisms of Evolution