Question 1

Which of these conditions are always true of populations evolving due to natural selection?
Condition 1: The population must vary in traits that are heritable.
Condition 2: Some heritable traits must increase reproductive success.
Condition 3: Individuals pass on most traits that they acquire during their lifetime.

Accepted Answer

For natural selection to occur, there must be variation in heritable traits within a population (Condition 1). Some of these heritable traits must confer a greater ability to survive and reproduce, leading to higher reproductive success for individuals carrying those traits (Condition 2). Condition 3, on the other hand, is not always true, as not all traits acquired during an individual's lifetime can be passed down to offspring.

Question 2

A farmer uses triazine herbicide to control pigweed in his field. For the first few years, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. Which of these statements explains why the pigweed reappeared?

Accepted Answer

The increasing number of pigweed suggests that triazine-resistant weeds were more likely to survive and reproduce, leading to the emergence of a population with resistance to the triazine herbicide.

Question 3

The following questions refer to the figure below, which shows an outcrop of sedimentary rock whose strata are labeled A-D.

If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?

Accepted Answer

C

Question 4

What are adaptations?

Accepted Answer

Adaptations refer to inherited characteristics of organisms that enhance their survival. These traits have evolved over time through the process of natural selection, allowing them to better compete for resources, evade predators, or survive in changing environments. Options A, B, and D do not accurately describe adaptations.

Question 5

Darwin and Wallace's theory of evolution by natural selection was revolutionary because it ________.

Accepted Answer

Darwin and Wallace's theory of evolution by natural selection challenged the idea of species being fixed and unchanging, and emphasized the importance of variation and change in populations. It did not prove that individuals acclimated to their environment over time, nor was it the first time a biologist had proposed that species changed through time (several scientists before Darwin had suggested similar ideas). While it did refute the idea of special creation, this was not the only nor the most revolutionary aspect of the theory.

Question 6

For which one of the following observations were both Lamarck's hypothesis and Darwin's hypothesis in complete agreement?

Accepted Answer

Both Lamarck's hypothesis and Darwin's hypothesis agree on the concept of gradual evolutionary change, which explains why organisms are well-suited to their environments. However, Lamarck's hypothesis also included the concept of acquired characteristics being inherited, which Darwin's hypothesis did not support.

Question 7

Fossils found in strata reveal that ________.

Accepted Answer

Fossils found in older strata show significant differences from living organisms, indicating that there has been significant evolutionary change over time. This supports the theory of evolution and contradicts the idea of innate drive towards complexity. It also indicates that geologic changes occur slowly over time, rather than quickly as option B suggests. The idea of unused body parts decreasing in size is also not supported by the fossil record.

Question 8

The cow Bos primigenius (which is bred for meat and milk) has a smaller brain and larger eyes than closely related wild species of ungulates. These traits most likely arose by ________.

Accepted Answer

The traits of smaller brain and larger eyes are not typical of wild ungulates, and their co-occurrence with human selection for high milk output and high muscle content strongly suggests that they arose through artificial selection.

Question 9

The following questions refer to the evolutionary tree in the figure below.
The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.

In Darwin's tree of life, each fork in the tree represents ________.

Accepted Answer

Each fork in the tree represents the most recent common ancestor of the subsequent branches. This is the basis of the concept of common descent, which forms the foundation of Darwin's theory of evolution. The branches themselves represent the lineages of descendants that have diverged and evolved over time.

Question 10

Starting from the wild mustard Brassica oleracea, breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Therefore, which of the following statements is correct?

Accepted Answer

The fact that breeders were able to create different strains from wild mustard suggests that there is heritable variation in this plant species that allows for the creation of different varieties.

Question 11

If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata?

Accepted Answer

The fossils of two closely related species can be found in two different strata because they must have existed at different times but still be closely related. Therefore, their remains must be found in two different layers of rock.

Question 12

Which of the following statements best explains why modification or change in an organ or tissue during the lifetime of an individual is not inherited?

Accepted Answer

Characteristics acquired during an organism's life, such as changes in organs or tissues through use or disuse, are not typically caused by changes in genes and are therefore not inherited.

Question 13

The Linnaeus classification system grouped organisms by ________.

Accepted Answer

Linnaeus classified organisms using a hierarchical system where each level of classification became increasingly more general.

Question 14

Prior to the work of Lyell and Darwin, the prevailing belief was that Earth is ________.

Accepted Answer

Prior to the work of Lyell and Darwin, the prevailing belief was that Earth is only a few thousand years old, and populations are unchanging, as held by the Biblical account of creation.

Question 15

Which statement illustrates the connection between natural selection and overreproduction of a population?

Accepted Answer

The answer of Which statement illustrates the connection between natural...

Question 16

After the drought of 1977, researchers hypothesized that on the Galápagos Island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?

Accepted Answer

The reliable feeding stations set up by the tourist company provide a consistent and abundant food source, which reduces selection pressure for larger, deeper beaks to crack tough fruits. As a result, there may be increased variation in beak size and shape over time as different beak types are favored by different seed types available at the feeding stations. This could lead to the emergence of new beak morphologies or the maintenance of existing variation in the population.

Question 17

When Cuvier considered the fossils found in the vicinity of Paris, he concluded that the extinction of species ________.

Accepted Answer

Cuvier concluded that the fossils he analyzed indicated that species had become extinct, but he did not believe in the idea of evolution.

Question 18

Which one of the following statements best defines artificial selection?

Accepted Answer

Artificial selection is a process by which humans intentionally breed plants or animals to produce offspring with selective traits, such as larger fruits or faster running speeds. This is different from natural selection, where traits that aid in survival and reproduction are naturally passed on to offspring. Option A describes natural selection, B is describing controlled breeding without the intention of selective traits, and D is describing another type of natural selection that favors beneficial mutations.

Question 19

The following question is based on information from Frank M. Frey, "Opposing Natural Selection from Herbivores and Pathogens May Maintain Floral-Color Variation in Claytonia virginica (Portulacaceae)," Evolution 58(11), 2004: 2426-37.
Claytonia virginica is a woodland spring herb with flowers that vary from white, to pale pink, to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time?

Accepted Answer

With the removal of slugs, the selective pressure against pink flowers due to herbivory is eliminated. Since bees prefer pink flowers, leading to greater fruit set, the percentage of pink flowers is expected to increase over time.

Question 20

Which pair of scientists below would probably have agreed with the process that is depicted by this tree?

Accepted Answer

Darwin and Wallace are associated with the theory of evolution through natural selection, which is represented by the branching and divergence of species in the tree.

Quiz 22: Descent with Modification: A Darwinian View of Life