Question 1

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations?
A) selection for drab coloration of the algae-eaters
B) selection for nocturnal algae-eaters (active only at night)
C) selection for larger female algae-eaters, bearing broods composed of more, and larger, young
D) selection for algae-eaters that become sexually mature at smaller overall body sizes
E) selection for algae-eaters that are faster swimmers

Accepted Answer

Predation pressure from pike-cichlids would favor traits that increase the survival of the algae-eaters. A drab coloration or being active only at night would decrease the chances of being seen by visual predators. Being a faster swimmer would also increase the likelihood of escaping predation. Selection for larger females with more and larger young could potentially increase the population size and buffer the effects of predation. Sexual maturity at smaller overall body sizes would allow for earlier reproduction and potentially increase the population's chances of survival. However, there is no clear advantage to having larger broods composed of more and larger young, making it the least likely outcome of predation pressure from pike-cichlids.

Question 2

Which of the following statements best describes theories?
A) They are nearly the same things as hypotheses.
B) They are supported by, and make sense of, many observations.
C) They cannot be tested because the described events occurred only once.
D) They are predictions of future events.

Accepted Answer

Theories are broader explanations or frameworks that unify and make sense of many observations and experiments within a field. Hypotheses are specific, testable predictions about phenomena that can support or disprove theories. Theories are constantly tested and refined, and they are supported by evidence from multiple sources. Theories are not predictions of future events, nor are they descriptions of events that occurred only once, as they are meant to be generalizable explanations.

Question 3

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?
A) Larger doses of DDT should have been applied.
B) All habitats should have received applications of DDT at about the same time.
C) The frequency of DDT application should have been higher.
D) None of the individual insects should have possessed genomes that made them resistant to DDT.
E) DDT application should have been continual.

Accepted Answer

The presence of individual insects with genomes that made them resistant to DDT was the main reason for the failure of DDT to permanently eradicate insect pests. Without resistant individuals present, DDT would have been a more effective solution in the long run. Thus, the successful eradication effort would have required that none of the individual insects possess genomes that made them resistant to DDT.

Question 4

Charles Darwin was the first person to propose
A) that evolution occurs.
B) a mechanism for how evolution occurs.
C) that Earth is older than a few thousand years.
D) a mechanism for evolution that was supported by evidence.
E) that population growth can outpace the growth of food resources.

Accepted Answer

The answer of Charles Darwin was the first person to...

Question 5

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?
A) Technological innovation in agricultural practices will permit exponential growth of the human population into the foreseeable future.
B) Populations tend to increase at a faster rate than their food supply normally allows.
C) Earth changed over the years through a series of catastrophic upheavals.
D) The environment is responsible for natural selection.
E) Earth is more than 10,000 years old.

Accepted Answer

Darwin learned from Malthus that populations tend to increase faster than their food supply, leading to competition for resources and ultimately, the selection of traits that allow for survival and reproduction in a given environment.

Question 6

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?
A) Characteristics acquired during an organism's life are generally not passed on through genes.
B) Spontaneous mutations can result in the appearance of new traits.
C) Only favorable adaptations have survival value.
D) Disuse of an organ may lead to its eventual disappearance.
E) If the giraffes did not have to compete with each other, longer necks would not have been passed on to the next generation.

Accepted Answer

This statement, known as Lamarckism, suggests that an organism can pass on characteristics it acquired during its lifetime to its offspring, which is not true according to the principles of genetics and evolution. Option A correctly states that acquired traits are not passed on through genes.

Question 7

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of
A) Cuvier.
B) Hutton.
C) Lamarck.
D) Darwin.
E) Lyell.

Accepted Answer

Lysenko's beliefs about the inheritance of acquired characteristics, where traits gained during an organism's lifetime could be passed on to its offspring, align with the ideas proposed by Lamarck. This is also known as Lamarckism or the theory of use and disuse.

Question 8

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?
A) All variation between individuals is due only to environmental factors.
B) The environment is changing at a relatively slow rate.
C) The population size is large.
D) The population lives in a habitat where there are no competing species present.

Accepted Answer

In order for natural selection to occur, there must be genetic variation between individuals. If all variation between individuals is due only to environmental factors, there is no genetic variation to act upon, and therefore no natural selection can occur.

Question 9

The role that humans play in artificial selection is to
A) determine who lives and who dies.
B) create the genetic variants, which nature then selects.
C) choose which organisms breed, and which do not.
D) train organisms to breed more successfully.
E) perform artificial insemination.

Accepted Answer

Humans choose which organisms breed in artificial selection, giving certain traits a selective advantage over others.

Question 10

Natural selection is based on all of the following except
A) genetic variation exists within populations.
B) the best-adapted individuals tend to leave the most offspring.
C) individuals who survive longer tend to leave more offspring than those who die young.
D) populations tend to produce more individuals than the environment can support.
E) individuals adapt to their environments, and thereby evolve.

Accepted Answer

Individuals do not actively adapt to their environment, but rather those who are already better adapted to their environment are more likely to survive and reproduce, passing on their favorable traits to their offspring.

Question 11

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?
A) If natural selection can change one gene's frequency in a population over the course of generations, then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones.
B) If an individual's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring.
C) If an individual acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will be the result.
D) A single mutation in a single gene in a single gamete will, if perpetuated, produce a new species within just two generations.

Accepted Answer

Darwin's theory of natural selection emphasized on the gradual accumulation of small genetic changes over a long period of time leading to the formation of new species. With the knowledge of genes and their typical mode of inheritance, Darwin would have agreed that natural selection can cause sufficient genetic change to produce new species over time, given enough time and enough genes. Therefore, option A is the most likely statement with which Darwin would have been in agreement. Option B is incorrect as somatic cell changes acquired during an individual's lifetime are not inherited by their offspring. Option C is incorrect as acquiring new genes by engulfing or being infected by another organism does not lead to the formation of a new genetic species. Option D is incorrect because forming a new species within just two generations with a single mutation is highly unlikely, and it would require several additional evolutionary processes beyond mutation and natural selection.

Question 12

Which of the following must exist in a population before natural selection can act upon that population?
A) genetic variation among individuals
B) variation among individuals caused by environmental factors
C) sexual reproduction
D) Three of the responses are correct.
E) Two of the responses are correct.

Accepted Answer

Natural selection depends on there being genetic differences between individuals, which allow some individuals to survive and reproduce more successfully than others.

Answer: D) Three of the responses are correct 
 Natural selection requires genetic variation among individuals, variation in traits that affects survival or reproduction, and inheritance of those traits. Sexual reproduction is not a requirement for natural selection, as it can also act on asexual populations through mutations and other mechanisms.

Question 13

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?
A) Species X and Y are not related to species Z.
B) Species X and Y share a greater number of homologies with each other than either does with species Z.
C) Species X and Y share a common ancestor that is still extant (in other words, not yet extinct).
D) Species X and Y are the result of artificial selection from an ancestral species Z.
E) Species X, Y, and Z share a common ancestor, but nothing more can be claimed than this.

Accepted Answer

Since species X and Y are placed in the same genus, they share a greater number of homologies with each other than either does with species Z. This choice is the best fit. Choice A is incorrect because all three species share a common ancestor. Choice C is also incorrect because the common ancestor of species X and Y is no longer extant. Choice D is incorrect because there is no evidence of artificial selection in the origin of these species. Choice E is too general and does not address the relationship between the species in question.

Question 14

Which of the following is the most accurate summary of Cuvier's consideration of fossils found in the vicinity of Paris?
A) extinction of species yes; evolution of new species yes
B) extinction of species no; evolution of new species yes
C) extinction of species yes; evolution of new species no
D) extinction of species no; evolution of new species no

Accepted Answer

Cuvier believed in extinction of species, but he did not believe in evolution of new species.

Question 15

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals.
2) A change occurs in the environment.
3) Genetic frequencies within the population change.
4) Poorly adapted individuals have decreased survivorship.
A) 2 → 4 → 1 → 3
B) 4 → 2 → 1 → 3
C) 4 → 1 → 2 → 3
D) 4 → 2 → 3 → 1
E) 2 → 4 → 3 → 1

Accepted Answer

Natural selection starts with a change in the environment (2), which then affects the survival of individuals based on their adaptations, leading to decreased survivorship of poorly adapted individuals (4). Well-adapted individuals then leave more offspring (1), resulting in a change in genetic frequencies within the population (3).

Question 16

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because
A) humans purposefully raise MRSA in large fermenters in an attempt to make the bacteria ever-more resistant.
B) S. aureus is cultivated by humans to replenish the soil with nutrients.
C) humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin.
D) Humans are becoming resistant to bacteria by taking methicillin.

Accepted Answer

Methicillin is a drug created by humans to combat bacterial infections, but frequent exposure to this drug in hospitals and other environments has led to the emergence of MRSA, which is resistant to methicillin. This can be considered artificial selection because humans are inadvertently selecting for bacteria with this resistance trait by creating an environment in which they are exposed to methicillin frequently. Choices A, B, and D are not correct because they do not accurately describe the process by which MRSA emerged.

Question 17

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier's attempt to explain the existence of
A) evolution.
B) the fossil record.
C) uniformitarianism.
D) the origin of new species.
E) natural selection.

Accepted Answer

Catastrophism was Cuvier's attempt to explain the existence of fossils in different layers of rock, which he believed were caused by catastrophic events such as floods or earthquakes. Therefore, B is the best choice as it directly relates to the concept of the fossil record.

Question 18

Which of Darwin's ideas had the strongest connection to Darwin having read Malthus's essay on human population growth?
A) descent with modification
B) variation among individuals in a population
C) struggle for existence
D) the ability of related species to be conceptualized in "tree thinking"
E) that the ancestors of the Galápagos finches had come from the South American mainland

Accepted Answer

Darwin's concept of struggle for existence, in which individuals with advantageous variations are more likely to survive and reproduce, was strongly influenced by Malthus's essay on human population growth. This idea was a key component of Darwin's theory of natural selection.

Question 19

What was the prevailing belief prior to the time of Lyell and Darwin?
A) Earth is a few thousand years old, and populations are unchanging.
B) Earth is a few thousand years old, and populations gradually change.
C) Earth is millions of years old, and populations rapidly change.
D) Earth is millions of years old, and populations are unchanging.
E) Earth is millions of years old, and populations gradually change.

Accepted Answer

Prior to the time of Lyell and Darwin, the prevailing belief was that Earth is a few thousand years old, and populations are unchanging. This view was largely influenced by religious beliefs and the interpretation of the Bible, which taught that all species had been created separately and did not change over time.

Question 20

A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true?
A) The amount of available food may have increased.
B) The parental generation of squirrels developed better eyesight due to improved diet; the subsequent squirrel generation inherited better eyesight.
C) The number of predators that prey upon squirrels may have decreased.
D) A and C could be true.
E) A, B, and C could be true.

Accepted Answer

From the given information, it is clear that the survival rate of squirrels increased from 50% to 90% in a single generation, and the population increased to 80. This suggests that either the amount of available food may have increased or the number of predators that prey upon squirrels may have decreased, or both. Therefore, options A and C could be true. However, there is no evidence to support the idea that the parental generation of squirrels developed better eyesight due to improved diet, and the subsequent squirrel generation inherited better eyesight, so option B is not supported by the given information. Therefore, the answer is D.

Quiz 19: Descent With Modification

Which of the following statements best describes theories?

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?

Charles Darwin was the first person to propose

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

The role that humans play in artificial selection is to

Natural selection is based on all of the following except

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

Which of the following must exist in a population before natural selection can act upon that population?

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Which of the following is the most accurate summary of Cuvier's consideration of fossils found in the vicinity of Paris?

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes) , was Cuvier's attempt to explain the existence of

Which of Darwin's ideas had the strongest connection to Darwin having read Malthus's essay on human population growth?

What was the prevailing belief prior to the time of Lyell and Darwin?