Question 1

Several dozen different proteins comprise the prokaryotic flagellum and its attachment to the prokaryotic cell, producing a highly complex structure. Certain proteins of the complex motor that drives bacterial flagella are modified versions of proteins that had previously belonged to plasma membrane pumps. This evidence best supports which of the following claims?
A) Natural selection produces organs that will be needed in future environments.
B) The motors of bacterial flagella must have originated in other organisms.
C) Natural selection can favor new structures that have been coupled together from parts of other structures.
D) Bacteria that possess flagella must have lost the ability to pump certain chemicals across their plasma membranes.

Accepted Answer

The evidence that certain proteins in the complex motor of bacterial flagella are modified versions of proteins from plasma membrane pumps supports the idea that natural selection can favor the development of new structures through the modification and repurposing of parts of other structures.

Question 2

The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?
A) the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
B) the persistence of some animal groups in anaerobic habitats
C) the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
D) the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria

Accepted Answer

The evolution of cellular respiration is directly linked to the use of oxygen to harvest energy from organic molecules, which became a fundamental process for most life forms following the increase in atmospheric oxygen. This process allowed organisms to efficiently produce ATP, the energy currency of the cell, using oxygen.

Question 3

If one organ is an exaptation of another organ, then which of the following statements is most accurate?
A) The two organs are homologous.
B) The two organs are undergoing convergent evolution.
C) The two organs occur in the same species.
D) The two organs have the same function.

Accepted Answer

Exaptation refers to a trait that has been co-opted for a use other than the one for which natural selection has built it, often implying that the trait is a modified form of an existing trait (organ) in an organism. Therefore, if one organ is an exaptation of another, the two organs are homologous, meaning they share a common ancestral origin but may have diverged in function.

Question 4

The prokaryotic flagellum is a complex structure consisting of several dozen different proteins. Which of the following statements best describes the origin of flagella in prokaryotes?
A) Natural selection cannot account for the evolution of the prokaryotic flagellum.
B) Ancestral versions of this protein assemblage were either less functional or had different functions than modern prokaryotic flagella.
C) Flagella could not have arisen by evolution because the structure is too complex to have evolved gradually.
D) The need for more complex structure must have driven evolution.

Accepted Answer

The evolution of the prokaryotic flagellum is best explained by the concept that ancestral versions of the proteins involved were either less functional or served different functions, which gradually evolved into the highly specialized and complex structure seen today. This is consistent with the principle of gradual evolution and natural selection, where simple structures evolve over time into more complex ones as mutations and natural selection act on variations within populations.

Question 5

Which of the following statements best explains how gene duplication events, such as those seen in the Hox gene complex, may have allowed the evolution of new morphological forms?
A) There are more copies of genes, meaning speciation had occurred by polyploidy.
B) The original gene copy is the outgroup, and the new gene copies are the adaptive radiation.
C) Without duplicated genes, species would be vulnerable to extinction.
D) One copy of a gene can perform the original function, while other copies are available to take on new functions.

Accepted Answer

Gene duplication events provide a mechanism for evolutionary innovation. When a gene is duplicated, one copy can continue to perform its original function, ensuring the organism's viability, while the other copies are free to accumulate mutations. These mutations can lead to new gene functions, potentially giving rise to new morphological features and contributing to the diversity of life. This process allows organisms to adapt to new environments or to exploit new ecological niches, driving evolutionary change.

Question 6

A female fly, carrying fertilized eggs, is hypothetically swept by high winds to an island far out to sea. She is the first and only fly to arrive on this island. Thousands of years later, her numerous descendents occupy the island and have overlapping geographic ranges. They are separated into several different species with different foods, mouthparts, egg-laying sites, and egg shapes. None of the species can fly and their balancing organs (halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. Which of these fly organs, as they exist in the description, best illustrates an exaptation?
A) the wings in the ancestral species
B) the halteres
C) the mouthparts
D) the eggs

Accepted Answer

Exaptation refers to a trait that has been co-opted for a use other than the one for which natural selection has built it. In this scenario, the halteres, originally used for balance during flight, have been repurposed for use in courtship displays, making them an example of exaptation.

Question 7

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of ________.
A) exaptation
B) changes in Hox gene expression
C) paedomorphosis
D) adaptive radiation

Accepted Answer

Exaptation refers to a trait that has been co-opted for a use other than the one for which natural selection has built it. The swim bladder is an example of exaptation, as it evolved from the air-breathing organ of an ancestral fish and was co-opted for buoyancy control.

Question 8

Insect wings may have begun to evolve as lateral extensions of the body that dissipated heat for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air. Additional selection resulted in refinement as flight-producing wings. If this hypothesis is correct, modern insect wings would be an example of which of the following?
A) loss of Hox genes in the evolution of new forms
B) mutation
C) exaptation
D) adaptive radiation

Accepted Answer

The hypothesis suggests that insect wings initially evolved for a purpose other than flight (thermoregulation) and later became adapted for flight. This is an example of exaptation, where a trait that originally served one function becomes co-opted for another function through natural selection.

Question 9

Which of the following statements best explains the existence of evolutionary trends, such as increasing body sizes among horse species?
A) A larger volume-to-surface area ratio is adaptive in many mammals.
B) Evolution generally progresses toward some goal.
C) Evolution tends toward increased complexity or increased size.
D) In particular environments, similar adaptations can be beneficial to more than one species.

Accepted Answer

Evolutionary trends, like increasing body size, occur because certain adaptations can be advantageous in specific environments, leading to similar traits evolving in different species.

Question 10

Which of the following statements best describes the evolution of complex eyes?
A) Complex eyes evolved through a series of steps that improved the functioning of the eyes.
B) Eyes in mollucs and vertebrates are descended from the same common ancestor.
C) Complex eyes arose fully formed.
D) The evolution of mollusc eyes was dependent on the evolution of vertebrate eyes.

Accepted Answer

Complex eyes evolved through a series of incremental modifications, each of which provided a survival advantage. This gradual improvement in function supports the idea that complex eyes did not appear suddenly but evolved over time through natural selection.

Question 11

Many species of snakes lay eggs. However, in the forests of northern Minnesota, where the growing season is short, only live-bearing snake species are present. Which of the following processes most likely resulted in the differences in snake reproduction?
A) natural selection leading to exaptations
B) sexual selection
C) species selection
D) goal direction in evolution

Accepted Answer

Species selection is the process where certain traits become more common in a population because they provide a survival advantage in a specific environment. In this case, live-bearing snakes are more suited to the short growing season in northern Minnesota, leading to their prevalence.

Question 12

Fossilized stromatolites ________.
A) formed around deep-sea vents
B) resemble structures formed by bacterial communities that are found today in some shallow marine bays
C) provide evidence that plants moved onto land in the company of fungi around 500 million years ago
D) contain the first undisputed fossils of eukaryotes

Accepted Answer

Stromatolites are layered structures formed by the mineralization of bacterial communities, particularly cyanobacteria. These communities are found today in shallow marine environments, such as bays, where they continue to form similar structures. This resemblance helps scientists understand the conditions under which ancient stromatolites formed and the role of microbial life in Earth's history.

Question 13

Scientists studying the origin of life have accomplished which of the following steps?
A) abiotic synthesis of protocells with self-replicating, catalytic RNA
B) formation of vesicles that use RNA as a template for DNA synthesis
C) formation of protocells that use DNA to direct the polymerization of amino acids
D) abiotic synthesis of RNA's bases (A, C, G, U)

Accepted Answer

Scientists have successfully demonstrated the abiotic synthesis of RNA's bases (adenine, cytosine, guanine, and uracil), which are fundamental components of RNA molecules.

Question 14

Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia?
A) The species became separated by convergent evolution.
B) The climates of the two regions are similar.
C) India is in the process of separating from the rest of Asia.
D) India was a separate continent until 45 million years ago.

Accepted Answer

India was a separate continent until about 45 million years ago, which led to a period of isolation. During this time, species in India evolved differently from those in Southeast Asia, resulting in the significant differences observed today.

Question 15

Large-scale, worldwide adaptive radiations have occurred in which of the following situations?
A) when there are no available ecological niches
B) after each of the big five mass extinctions
C) after colonization of an isolated island that contains suitable habitat and few competitor species
D) whenever an evolutionary innovation was needed for organisms to thrive

Accepted Answer

The answer of Large-scale, worldwide adaptive radiations have occurred in...

Question 16

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative of ________.
A) the influence of environment on development
B) paedomorphosis
C) a change in a developmental gene or in its regulation that altered the spatial organization of body parts
D) heterochrony

Accepted Answer

This is an example of a change in a developmental gene or its regulation that altered the spatial organization of body parts, which is what Hox genes influence by determining the body plan of an organism during embryonic development.

Question 17

A swim bladder is a gas-filled sac that helps fish maintain buoyancy and evolved from the lungs of ancient fish. This evolutionary change is an example of which of the following processes?
A) exaptation
B) changes in Hox gene expression
C) paedomorphosis
D) adaptive radiation

Accepted Answer

Exaptation refers to a trait that has been co-opted for a use other than the one for which natural selection has built it. The swim bladder is an example of exaptation, as it evolved from the lungs of ancient fish to help modern fish maintain buoyancy.

Question 18

Evolutionary biologists claim that the complex eyes in some molluscs (e.g., squids and octopuses) and vertebrates evolved independently. Which of the following observations, if made, would support this claim?
A) The lens structures of mollusc and vertebrate eyes are similar.
B) The light-sensing cells of both molluscs and vertebrates are structurally different.
C) The proteins that absorb light in both molluscs and vertebrates have almost identical amino acid sequences.
D) The bones to which the eyes of molluscs and vertebrates attach are different.

Accepted Answer

The structural difference in light-sensing cells between molluscs and vertebrates supports the idea of independent evolutionary paths for complex eyes in these groups, indicating convergent evolution rather than a shared ancestral trait.

Quiz 25: Macroevolution

The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?

If one organ is an exaptation of another organ, then which of the following statements is most accurate?

The prokaryotic flagellum is a complex structure consisting of several dozen different proteins. Which of the following statements best describes the origin of flagella in prokaryotes?

Which of the following statements best explains how gene duplication events, such as those seen in the Hox gene complex, may have allowed the evolution of new morphological forms?

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of ________.

Which of the following statements best explains the existence of evolutionary trends, such as increasing body sizes among horse species?

Which of the following statements best describes the evolution of complex eyes?

Many species of snakes lay eggs. However, in the forests of northern Minnesota, where the growing season is short, only live-bearing snake species are present. Which of the following processes most likely resulted in the differences in snake reproduction?

Fossilized stromatolites ________.

Scientists studying the origin of life have accomplished which of the following steps?

Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia?

Large-scale, worldwide adaptive radiations have occurred in which of the following situations?

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative of ________.

A swim bladder is a gas-filled sac that helps fish maintain buoyancy and evolved from the lungs of ancient fish. This evolutionary change is an example of which of the following processes?

Evolutionary biologists claim that the complex eyes in some molluscs (e.g., squids and octopuses) and vertebrates evolved independently. Which of the following observations, if made, would support this claim?