Question 1

Which of the following is required for natural selection to occur in a population?

Accepted Answer

All of the choices listed are required for natural selection to occur in a population. Variation in the population provides the raw material for selection to act upon, genetics ensure that these variations are passed on to future generations, differential reproduction ensures that the fittest individuals have more offspring that survive to reproduce, and the accumulation of adaptive traits means that the population gradually becomes better adapted to its environment over time.

Question 2

In the case of the peppered moths in England,when Kettlewell set up cameras to document that more white or black moths were eaten by birds on clean or sooty trees,he was verifying which factor involved in evolution by natural selection?

Accepted Answer

Kettlewell was testing the idea that some individuals (in this case, moths) are better adapted to a particular environment (sooty or clean trees) than others. This is the key concept of evolution by natural selection. The other choices (A, B, and C) are also important concepts in evolution, but they are not directly related to what Kettlewell was testing with the peppered moth experiment.

Question 3

Gene mutation occurs at any time,without respect to the mutation's adaptive value or benefit to the organism.

Accepted Answer

Gene mutations can occur randomly, without any selection pressure or benefit to the organism. However, whether or not the mutation confers an advantage to the organism in its environment will determine if it becomes more common in subsequent generations through natural selection.

Question 4

While studying gull egg laying abilities a researcher noted that the birds laid an average of 7 - 9 eggs per clutch at the beginning of the study.After studying the population for 15 generations the researcher noted that the birds now laid an average of 3- 4 eggs per clutch.What type of natural selection is occurring in the population of gulls?

Accepted Answer

Stabilizing selection occurs when individuals with intermediate traits have higher fitness than those with extreme traits. In this case, the gulls that lay an intermediate number of eggs (between 3 and 9) may have higher fitness than those laying fewer or more eggs. Over time, this could lead to the population evolving to have an average clutch size in the intermediate range.

Question 5

In a population,the allele frequency for red flower color remained at 0.7 and the allele frequency for white flower remained at 0.3 for six generations.This ____ an example of a Hardy-Weinberg equilibrium in that ___________.

Accepted Answer

In a population in Hardy-Weinberg equilibrium, the allele frequencies should remain constant from generation to generation. Therefore, the fact that the allele frequencies for red and white flower colors remained unchanged for six generations suggests that there was no evolution occurring. So, it is an example of a Hardy-Weinberg equilibrium. The correct option is B.

Question 6

What type of selection is occurring in a population if the distribution graph shifts from the left end of the spectrum to the far right end?

Accepted Answer

A shift from the left end of a spectrum to the far right end indicates a directional selection, where selection pressures are favoring individuals with extreme traits at one end of the spectrum over the other.

Question 7

The northern elephant seal was hunted almost to extinction during the 18^th and 19^th centuries.Less than 100 seals were left to contribute to the gene pool of their future generations.Since the early 20^th century,the elephant seals have been protected by law in both the U.S.and Mexico.Over 100,000 seals now inhabit the western shores of North America,all related to the small population that survived the slaughter of hunters. Scientists fear the elephant seals may be more susceptible to disease and pollution due to a ______.

Accepted Answer

The Northern elephant seals were almost hunted to extinction during the 18th and 19th centuries, leaving less than 100 seals to contribute to the gene pool of their future generations. This led to a bottleneck effect, where the genetic diversity of the population was drastically reduced. As a result, scientists fear that the elephant seals may be more susceptible to disease and pollution. Therefore, the best choice is D, the bottleneck effect.

Question 8

Over the course of millions of years various environments have changed.As grasslands slowly took the place of forests the inhabitants were forced to adapt or they went extinct.During this time period the horse evolved from a small cat sized creature to the size of the modern horses we see today.This is an example of which type of natural selection?

Accepted Answer

Directional natural selection occurs when a certain trait is favored over others, leading to a shift in the population towards that trait. In this case, the shift towards larger size in horses was favored as the environment changed from forests to grasslands, allowing for greater speed and agility in open spaces. This resulted in the evolution of larger horses over millions of years.

Question 9

Another student proposes that handedness could just as easily be passed to children by how the parents carry the child and interact with it,a learning process that may perpetuate from the parents' handedness.Assuming all parents and children are expressing their "true handedness," the occurrence of which case below would cast the most serious doubt on a simple genetic basis for handedness,with left-handedness recessive?

Accepted Answer

Two left-handed parents having a right-handed child would cast the most serious doubt on a simple genetic basis for handedness with left-handedness being recessive, because if left-handedness were recessive, two left-handed (recessive) parents would not typically produce a right-handed (dominant) child.

Question 10

A population of organisms that reproduce asexually without gametes from other individuals will display more variation than a population that reproduces sexually.

Accepted Answer

A population that reproduces sexually will have more genetic variation because the offspring inherit traits from both parents, which can lead to new combinations of genes. In asexual reproduction, the offspring are genetically identical to the parent, so there is no potential for genetic variation to arise from mixing of genes from multiple individuals.

Question 11

While we have seen how natural selection and the use of pesticides can lead to the development of resistant varieties of insects,two economically important flies,the Mediterranean fruit fly (Medfly)and the screwworm fly,can be driven to local extinction by the continuous release of sterile flies of those species.The critical factor is that the female of these species only mates once.But which of the following is/are also necessary for sterile release to work?

Accepted Answer

All of the choices are correct. In order for sterile release to work, it is important that the target species is one defined species, so that the sterile males do not mate with other species. Additionally, the insects must be able to be raised artificially in large numbers to ensure a sufficient release population. The insects to be released must also be sterilized without affecting their ability to attract a mate in the wild, which is achieved through radiation.

Question 12

British land snails are an example of disruptive selection.In the grassy fields,the light-banded snails escape bird predators.In the darker forest,the dark snails survive and the light-banded snails are eaten.As long as the snails continue to cruise across the British landscape mating at the same season,why doesn't this "disruptive selection" eventually lead to two separate species?

Accepted Answer

Disruptive selection alone is not enough to lead to the formation of two separate species unless there is some kind of reproductive isolation that prevents gene flow between the light-banded and dark snails. Without reproductive isolation, the light-banded and dark snails will continue to mate and exchange genetic material, preventing them from evolving into two separate species.

Question 13

Social research indicates that a person is most likely to marry someone from the same village or city,or a high school or college classmate.Therefore,the Hardy-Weinberg equilibrium does not apply well to human populations because

Accepted Answer

The Hardy-Weinberg equilibrium assumes random mating across the whole population, which is not the case in human populations where individuals tend to marry someone from the same village or city, or a high school or college classmate. Therefore, the random pairing assumption does not apply, and the Hardy-Weinberg equilibrium does not hold true.

Question 14

If early Viking explorers in Greenland and North America had survived and become the main ancestors of early North American settlers,rather than the mixture of immigrants from across Europe and other continents,today there would be a much higher incidence of Nordic traits in the U.S.population.Such a scenario would demonstrate

Accepted Answer

The scenario described in the question represents the Founder Effect, where a small group of individuals becomes the founding population of a new area, leading to a limited genetic diversity and a higher incidence of certain traits. In this case, the early Viking explorers represents the founding population of North America, leading to a hypothetical higher incidence of Nordic traits if they had become the main ancestors of early North American settlers.

Question 15

The Hardy-Weinberg equilibrium is usually met in populations in changing environments.

Accepted Answer

The Hardy-Weinberg equilibrium assumes that there is no selection, mutation, migration, or genetic drift in the population, which is unlikely to occur in changing environments. Therefore, the Hardy-Weinberg equilibrium is usually not met in such populations.

Question 16

The bottleneck effect is thought to be responsible for the loss of variability and loss of fertility in the cheetah species.

Accepted Answer

The cheetah species experienced a bottleneck event in the past, resulting in a significant loss of genetic diversity. This loss of variability is likely responsible for the high incidence of genetic disorders and reduced fertility observed in cheetah populations today.

Question 17

Which of the following reflect(s)the likely presence of (a)gene mutation(s)?

Accepted Answer

All the choices describe scenarios where gene mutations are likely present: A) radiation causing variability in offspring, B) a chemical causing a physical mutation, C) bacteria developing resistance to an antibiotic, and D) a direct observation of a change in the DNA sequence.

Question 18

An allele becomes the most common allele in a population by becoming the dominant allele.

Accepted Answer

An allele becoming the most common allele in a population does not necessarily mean it is the dominant allele. It can be due to factors such as genetic drift, natural selection or migration.

Question 19

Perissodus are small,scale-eating fish that live in Lake Tanganyika in Africa.They attack larger fish from behind.The right-mouthed Perissodus attack on the left side of the larger fish and the left-mouthed Perissodus attack on the right side of the larger fish.The existence of the right-mouthed variety ensures the equally successful existence of the left-mouthed variety.This is an example of:

Accepted Answer

This is an example of frequency dependent selection because the success of each variety depends on the frequency of the other variety. If one variety becomes too common, its success decreases as the larger fish learn to recognize and avoid its attack. Therefore, to maintain balance and success, the frequency of each variety must remain relatively equal.

Question 20

The Founder Effect is an example of genetic drift in which rare alleles occur at a higher frequency in a population isolated from the general population.

Accepted Answer

The statement is correct, as the Founder Effect is a type of genetic drift that occurs when a small group of individuals from a larger population establishes a new population in a different location, resulting in a different allele frequency from the original population. This can lead to the increased prevalence of certain rare alleles in the new population.

Quiz 16: How Populations Evolve