Question 1

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 emergence of resistance to DDT in insect populations was the main factor in the failure of DDT to permanently eradicate insect pests. Therefore, the only solution that would have made the eradication effort successful in the long run would have been if none of the individual insects possessed genomes that made them resistant to DDT.

Question 2

Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ?
A) The appendix can be surgically removed with no immediate ill effects.
B) The appendix might have been larger in fossil hominids.
C) The appendix has a substantial amount of defensive lymphatic tissue.
D) Individuals with a larger-than-average appendix leave fewer offspring than those with a below-average-sized appendix.
E) In a million years, the human species might completely lack an appendix.

Accepted Answer

Option C states that the appendix has a substantial amount of defensive lymphatic tissue, indicating that it may still have an important function in the immune system. This contradicts the claim that the appendix is a completely vestigial organ.

Question 3

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D.
  
Figure 22.1
-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?
A) one stratum
B) two strata
C) three strata
D) four strata

Accepted Answer

The only two strata that contain the fossils of x are Stratum B and Stratum D.

Question 4

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?
A) All organisms require energy.
B) All organisms use essentially the same genetic code.
C) All organisms reproduce.
D) All organisms show heritable variation.
E) All organisms have undergone evolution.

Accepted Answer

The fact that all organisms use essentially the same genetic code provides strong evidence for a common origin of all life on Earth. This is because the genetic code is the language by which DNA is read and translated into proteins, and is shared by all living organisms. The similarity in the genetic code across all life forms strongly suggests that they all descended from a common ancestor.

Question 5

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?
A) by identifying the bones as being homologous structures
B) by the principle of convergent evolution
C) by proposing that humans, bats, and dolphins share a common ancestor
D) Three of the statements above are correct.
E) Two of the statements above are correct.

Accepted Answer

The similarities in bone structures among humans, bats, and dolphins are interpreted as evidence of homologous structures (A) and a shared common ancestor (C), indicating evolutionary relationships. Convergent evolution (B) explains similar traits in unrelated species due to similar environmental pressures, not shared ancestry, so it does not apply in this context.

Question 6

What is true of pseudogenes?
A) They are composed of RNA, rather than DNA.
B) They are the same things as introns.
C) They are unrelated genes that code for the same gene product.
D) They are vestigial genes.

Accepted Answer

Pseudogenes are non-functional copies of genes that have become inactive over time through mutations. They are therefore considered vestigial or "dead" genes.

Question 7

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that
A) island forms and mainland forms descended from common ancestors.
B) common environments are inhabited by the same organisms.
C) the islands were originally part of the continent.
D) the island forms and mainland forms are converging.
E) island forms and mainland forms have identical gene pools.

Accepted Answer

The fact that organisms on islands are closely related to similar forms found on the nearest continent suggests that they have descended from a common ancestor. This is known as the theory of evolution, which proposes that all living organisms on Earth share a common ancestry and have evolved over time through natural selection and other selective pressures. The similarity between island and mainland forms is evidence that they share a common ancestry, and that the island forms have evolved in isolation from their mainland counterparts.

Question 8

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D.
  
Figure 22.1
-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?
A) A
B) B
C) C
D) D

Accepted Answer

In stratigraphy, the principle of superposition states that in an undeformed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one below it. Therefore, if fossils of two closely related species are found in a particular stratum, their most recent common ancestor would most likely be found in a lower (older) stratum, which is indicated by option C.

Question 9

Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds)and seals (which are mammals)have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals?
A) homologous; homologous
B) analogous; homologous
C) homologous; analogous
D) analogous; analogous

Accepted Answer

The forelimbs of penguins and seals are homologous because they share a common ancestor that had forelimbs adapted for terrestrial movement. However, the flippers of penguins and seals are analogous because they have evolved convergently for a similar purpose (swimming) despite having different structures and developmental origins.

Question 10

If two modern organisms are distantly related in an evolutionary sense, then one should expect that
A) they live in very different habitats.
B) they should share fewer homologous structures than two more closely related organisms.
C) their chromosomes should be very similar.
D) they shared a common ancestor relatively recently.
E) they should be members of the same genus.

Accepted Answer

The less related two organisms are, the less homologous structures (trait similarities due to shared ancestry) they share. This is because as new species evolve, they develop new traits that may not have been present in their common ancestor.

Answer: D 
 The more distantly related two organisms are, the longer ago they had a common ancestor. Conversely, closely related organisms share a more recent common ancestor.

A, C, and E are not necessarily true statements in all cases of distantly related organisms.

Question 11

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?
A) None of the organisms depicted by the tree ate the same foods.
B) Some of the organisms depicted by the tree had lived in different habitats.
C) The skeletal remains of the organisms depicted by the tree were incomplete (in other words, some bones were missing).
D) Transitional fossils had not been found.
E) Relationships between DNA sequences among the species did not match relationships between skeletal patterns.

Accepted Answer

DNA sequence comparison is considered the most reliable method for constructing evolutionary trees. If the relationships between DNA sequences among the species did not match relationships between skeletal patterns, it casts the most doubt on the accuracy of the evolutionary tree. The other options may affect the accuracy of the tree but to a lesser extent.

Question 12

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?
A) These genes should continue to be maintained in case the antibiotics ever appear.
B) These bacteria should be outcompeted and replaced by bacteria that have lost these genes.
C) The bacteria should try to make the cost worthwhile by locating, and migrating to, microenvironments where traces of antibiotics are present.
D) The bacteria should start making and secreting their own antibiotics.

Accepted Answer

When antibiotics are missing, there is no selection pressure for maintaining antibiotic resistance genes, meaning that the cost of maintenance becomes a burden. In such an environment, bacteria that have lost these genes will have a competitive advantage over those that still carry them, leading to their replacement over time.

Question 13

A high degree of endemism is most likely in environments that are
A) easily reached and heterogeneous.
B) isolated and heterogeneous.
C) isolated and homogeneous.
D) isolated and extremely cold.
E) easily reached and homogeneous.

Accepted Answer

Endemism refers to the occurrence of unique species within a specific geographic area. Isolated environments, by definition, have limited opportunities for species to colonize from other areas, which can lead to the evolution of distinct and unique species. Heterogeneous environments may still allow for some mixing of species, whereas homogeneous environments may have less variation in resources, which can limit the variety of species that can survive. The extreme cold may also limit the number of species that can survive, but it does not necessarily lead to endemism.

Question 14

What must be true of any organ that is described as vestigial?
A) It must be analogous to some feature in an ancestor.
B) It must be homologous to some feature in an ancestor.
C) It must be both homologous and analogous to some feature in an ancestor.
D) It need be neither homologous nor analogous to some feature in an ancestor.

Accepted Answer

A vestigial organ is one that has lost its original function in the course of evolution. If an organ is homologous to a similar feature in an ancestor, but has lost its function, it can be considered vestigial. Analogy refers to a superficial similarity in function or form between different organisms or body parts, which may not have a common ancestry. Therefore, only homology is necessary for an organ to be considered vestigial.

Question 15

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?
A) Natural selection cannot account for losses, only for innovations.
B) Natural selection accounts for these losses by the principle of use and disuse.
C) Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.
D) The ancestors of these organisms experienced harmful mutations that forced them to find new habitats that these species had not previously used.

Accepted Answer

Natural selection accounts for these losses when under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits. In the case of cave-dwelling organisms, eyes were no longer useful because they were in complete darkness, and the energy required to maintain them was not worth it. In tapeworms, the digestive system became unnecessary because they infect the intestines of their hosts, allowing them to directly absorb nutrients, thus making digestion useless. In the case of whales, hind limbs were no longer needed because evolution favored the development of streamlined bodies for efficient swimming in the water, and hind limbs would have only created drag and slowed them down.

Question 16

Of the following anatomical structures, which is homologous to the bones in the wing of a bird?
A) cartilage in the dorsal fin of a shark
B) bones in the hind limb of a kangaroo
C) chitinous struts in the wing of a butterfly
D) bony rays in the tail fin of a flying fish
E) bones in the flipper of a whale

Accepted Answer

The bones in the flipper of a whale are homologous to the bones in the wing of a bird as both are used for propelling through a fluid medium (water and air, respectively). While the other structures listed may have similar functions, they are not homologous to the bird wing bones.

Question 17

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?
A) The two species live at great distance from each other.
B) The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.
C) The sizes of the structures in adult members of both species are similar in size.
D) Both species are well adapted to their particular environments.

Accepted Answer

Homology refers to similarities between species that arise from a common ancestor, which is best supported by genetic evidence such as shared proteins and nearly identical nucleotide sequences. Convergent evolution, on the other hand, refers to the independent evolution of similar traits in species of different lineages, often as a result of adapting to similar environments or ecological niches, without a common genetic basis for the trait.

Question 18

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D.
  
Figure 22.1
-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. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?
A) 
B) 
C) 
D) 
E)

Accepted Answer

The answer of The following questions refer to Figure 22.1,...

Question 19

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are
A) homologous.
B) examples of convergent evolution.
C) adaptations to a common environment.
D) Three of the responses above are correct.
E) Two of the responses above are correct.

Accepted Answer

The dorsal fins and tails of ichthyosaurs and fish are examples of convergent evolution (B) and adaptations to a common environment (C), making them not homologous but rather analogous structures that evolved independently in response to similar environmental challenges.

Question 20

If one wanted to find the largest number of endemic species, one should visit which of the following geological features (assuming each has existed for several millions of years)?
A) an isolated ocean island in the tropics
B) an extensive mountain range
C) a midcontinental grassland with extreme climatic conditions
D) a shallow estuary on a warm-water coast

Accepted Answer

Isolated ocean islands in the tropics are known to have the largest number of endemic species due to their isolation, geological history, and unique climate. These factors have allowed for the evolution of unique species and ecologies that are not found anywhere else in the world. The other options listed may have some degree of endemism but are not as well-known for having the highest number of endemic species.

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

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?

Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ?

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Figure 22.1 -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?

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?

What is true of pseudogenes?

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. Figure 22.1 -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?

If two modern organisms are distantly related in an evolutionary sense, then one should expect that

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?

A high degree of endemism is most likely in environments that are

What must be true of any organ that is described as vestigial?

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

Of the following anatomical structures, which is homologous to the bones in the wing of a bird?

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are

If one wanted to find the largest number of endemic species, one should visit which of the following geological features (assuming each has existed for several millions of years) ?