Evolution EOC Review

Multiple Choice

Scientists lack enough evidence to conclude how the first organic molecules formed or arrived on Earth. However, the results of the Miller-Urey experiment and related experiments support which of these mechanisms for organic molecule synthesis?

• As Earth cooled, amino acids and other compounds fell to the surface in raindrops.

• During a volcanic eruption, gases from Earth's interior reacted with one another to form amino acids.

• During a lightning strike, chemicals in the atmosphere reacted to form amino acids.

• As the first cells formed, they released urea and other organic wastes into the surrounding water

Multiple Choice

Scientists have proposed that on early Earth, gases in the atmosphere reacted to form simple organic molecules. Does evidence exist for this proposal?

• Direct evidence exists. Scientists have discovered examples of the first organic molecules.

• Indirect evidence exists. Scientists have re-created conditions of the early atmosphere and observed reactions among the gases.

• Indirect evidence exists. The earliest fossils reveal traces of the earliest organic molecules.

• No evidence exists. Scientists have tried to re-create conditions of the early atmosphere, but they have failed to observe chemical reactions.

Multiple Choice

Which of these events occurred, according to endosymbiotic theory?

• Chloroplasts and mitochondria originated as free-living prokaryotic organisms.

• Cell nuclei originated as free-living prokaryotic organisms.

• Mitochondria attached to the cell membranes of single-celled prokaryotes to form multicellular eukaryotes.

• Chloroplasts were expelled from eukaryotic cells to become free-living algae.

Multiple Choice

Endosymbiotic theory is most useful for explaining the development of which of these organisms?

• prokaryotes that could perform photosynthesis 

• single-celled eukaryotes that could gain energy by combining food with oxygen

• multicellular plants and animals that could live either on land or in the water

• single-celled eukaryotes that kept their DNA in a membrane-bound nucleus

Multiple Choice

The endosymbiotic theory provides an explanation for the development of eukaryotic cells. Which observation provides the strongest evidence in support of the endosymbiotic theory?

• Mitochondria do not survive when they are removed and separated from a eukaryotic cell.

• Bacteria and algae have been observed to live inside eukaryotic cells.

• The cell membranes of prokaryotes and eukaryotes have a similar structure, including proteins embedded in a lipid bilayer.

• Chloroplasts are found in plant cells, but not animal cells.

Multiple Choice

The diagram describes a proposed evolutionary relationship among three ancient species, all of which were relatives of modern whales.

What evidence would MOST STRONGLY support the evolutionary relationship described in the diagram?

• data from experiments on whale behavior

• the number of fossil discoveries of each species

• a comparison of the fossil skeletons of the species

• a comparison of the ages of the fossils of each species

Multiple Choice

The diagram supports which of these conclusions about the three ancient species?

• Similar body parts among the three species, such as the mouth, legs, and tail, are examples of homologous structures.

• Similar body parts among the three species, such as the mouth, legs, and tail, are examples of analogous structures.

• The hip and shoulder bones in each of the three species are examples of vestigial structures.

• The hip and shoulder bones in each of the three species are examples of analogous structures.

Multiple Choice

A scientist claims that after the first single-celled organisms formed on Earth, conditions would not sustain multicellular organisms for millions of years. Which statement provides the STRONGEST evidence to support this claim?

• Earth's early atmosphere lacked oxygen, which multicellular organisms need to break apart food.

• Earth's early atmosphere lacked nitrogen, which multicellular organisms need to synthesize proteins.

• Earth's surface was much too hot to support liquid water, which multicellular organisms need to survive.

• Earth's surface was much too cold to support liquid water, which multicellular organisms need to survive.

Multiple Choice

Scientists have proposed the RNA World hypothesis to explain how information-carrying molecules developed. The hypothesis states that RNA existed before DNA. Eventually, several steps led to DNA-directed protein synthesis.

Which observation of RNA provides the strongest evidence in support of the RNA World hypothesis?

• Under certain circumstances, RNA molecules can act to replicate themselves.

• Generally, DNA acts as a template to synthesize RNA, which then directs protein synthesis.

• RNA is similar to DNA, but contains uracil instead of thymine.

• Both RNA are made of the same elements, including carbon, oxygen, nitrogen, and phosphorus

In 1953, Stanley Miller and Harold Urey hypothesized that organic compounds could have been produced from the inorganic gases that made up Earth's early atmosphere. The results of an experiment provided evidence in support of the hypothesis.

In the years that followed, scientists conducted similar experiments to test a variety of possible conditions on the early Earth. The results of some of these experiments are shown in the table. 

Multiple Choice

Taken together, the results of the experiments provide the STRONGEST support for which of these conclusions?

• Earth's early atmosphere contained compounds of carbon, nitrogen, oxygen, and hydrogen, which are component elements of amino acids.

• Amino acids may have formed in the atmosphere of early Earth, assuming that the atmospheric gases included the necessary elements.

• Most amino acids formed in the atmosphere of early Earth, and not on the surface or in liquid water.

• If amino acids formed in the atmosphere of early Earth, they were the first organic molecules to form there.

Multiple Choice

The wings of ostriches are examples of vestigial structures. The wings provide evidence for which of these evolutionary relationships?

• A new bird species without wings will evolve from ostriches.

• A new bird species that has useful wings will evolve from ostriches.

• An ancestor of ostriches had useful wings.

• An ancestor of ostriches had vestigial structures.

Multiple Choice

The wing of a bird and the front limb of a mammal have a similar number and arrangement of bones. Which evolutionary relationship explains these similarities?

• The wing and front limb are homologous structures; each evolved from a common ancestor.

• The wing and front limb are analogous structures; each evolved from a common ancestor.

• The wing and front limb are analogous structures; each evolved independently.

• The wing and front limb are vestigial structures; one evolved from the other.

Multiple Choice

A scientist argues that the hair of mammals and the feathers of birds are analogous structures. If the scientist is correct, what is the evolutionary relationship between hair and feathers?

• Either hair evolved from feathers, or feathers evolved from hair.

• Both hair and feathers evolved from the same structure in a common ancestor of birds and mammals.

• Hair evolved in mammals at the same time as feathers evolved in birds.

• The evolution of hair in mammals occurred independently of the evolution of feathers in birds.

Multiple Choice

John states the following claim.

"Biogeography provides evidence for the theory of evolution."

To support this claim, which evidence would be MOST useful for John to cite?

• A sequence of fossils shows that horses became smaller over time.

• Polar bears and grizzly bears are similar in many ways, but are adapted to live in different regions.

• Farm crops developed in Asia are now raised successfully in regions all over the world.

• Fossils of plants and animals have been found on Antarctica, which now is covered in ice.

Multiple Choice

Tiktaalik was an ancient fish that could support its weight as land animals do. Scientists claim that Tiktaalik is a representative of an evolutionary stage between fishes and tetrapods, or four-legged land animals. Which is one way that fossils of Tiktaalik support this claim?

• Tiktaalik fossils are found in rock layers that also hold modern tetrapods.

• Tiktaalik fossils are found in rock layers that also hold modern fishes.

• Tiktaalik fossils have been dated to a wide variety of periods of geologic time.

• Tiktaalik fossils date to the period of geologic time when the first tetrapods appeared.

Multiple Choice

A team of scientists discovers a fossil of an ancient plant species. They report that the plant developed from an embryo and had vascular tissues, but it did not have seeds. The ancient plant might have been an ancestor of which set of plants?

• mosses only

• ferns only

• mosses or ferns only

• ferns, cone-bearing plants, or flowering plants

Multiple Choice

Do fossils provide a complete record of all the extinct species that lived on Earth? Why or why not?

• Yes, because all species left fossils behind.

• Yes, because the traits of many species can be inferred from a single fossil.

• No, because many species went extinct without leaving fossils behind.

• No, because fossils break apart after about 65 million years.

Multiple Choice

A team of scientists is excavating fossils from a rock layer. They discover fossils of trilobites, which are useful as index fossils. Which information about the rock layer is provided by the trilobite fossils?

• the absolute age of the rocks

• the absolute age of the fossils contained in the rocks

• the number of fossils that the rocks contain

• the approximate or relative ages of the rocks and the fossils they contain

Multiple Choice

Fossil evidence shows that some species changed very little over geologic time, while others changed gradually and at a relatively constant rate. In many cases, however, species changed very rapidly during relatively brief time spans.

The pattern of punctuated equilibrium applies to the evolution of which group of species?

• all species that developed new adaptations over time

• species that evolved very rapidly during relatively brief time spans

• species that evolved gradually and at a relatively constant rate

• species that changed very little over geologic time.

Multiple Choice

The diagram shows the rock layers of two mountains, labeled A and B. The two mountains are located thousands of kilometers apart, on different continents. Both mountains have a layer of limestone, as shown by the labels.

Janice claims that the limestone layers of the two mountains are in fact part of the same layer. She thinks that after the limestone formed, tectonic forces broke apart and separated the layer.

Which observation would provide the strongest evidence in support of Janice's claim?

• Fossils of marine animals are found in the limestone of Mountain A, but not Mountain B.

• Index fossils are found in many layers of Mountain A, but not Mountain B.

• Matching index fossils are found in the limestone layers of both mountains.

• Fossils from both layers contain small amounts of carbon-14.

Multiple Choice

A scientist is studying the fossil record to construct an evolutionary lineage for an order of fishes. The scientist proposes that the lineage involves long periods of little change to species and then brief periods of significant changes. Is the scientist’s proposal consistent with modern evolutionary theory?

• Yes, the scientist is describing a pattern of punctuated equilibrium.

• Yes, but only if the brief periods of significant changes occurred after mass extinctions.

• No, species evolve only gradually and at a relatively constant rate of change.

• No, species evolve only gradually, although the rate of change may vary among evolutionary lineages.

Multiple Choice

According to one scientific study, the ancient ancestor of all placental mammals was about the size of a shrew or rat. It climbed trees and ate insects. It evolved soon after the mass extinction that killed the dinosaurs.

As shown by the cladogram, several classes of mammals evolved from the common mammal ancestor. Each line in the diagram represents an evolutionary lineage.

The cladogram describes an example of which macroevolutionary pattern, and for what reason?

• coevolution, because all of the evolutionary lineages led to mammals that are alive today

• coevolution, because similar changes occurred in each evolutionary lineage

• adaptive radiation, because an ancient ancestor gave rise to many species with diverse adaptations

• No. They are not adaptations because they evolved by chance, and not by natural selection.

Multiple Choice

According to the cladogram, which set of traits occurs in cone-bearing plants, but not ferns?

• seeds only

• seeds and flowers

• embryo and vascular tissues

• embryo, vascular tissues, and seeds

Multiple Choice

What conclusion about embryos is supported by the evidence in the cladogram?

• Embryos evolved at the same time as vascular tissues, seeds, and flowers.

• Embryos became less common as plants evolved over time, and are not present in modern plant groups.

• An embryo evolved in an ancient ancestor of mosses, ferns, cone-bearing plants, and flowering plants.

• ferns, cone-bearing plants, or flowering plants

Multiple Choice

The cladogram shown below describes the evolutionary relationship among several species, labeled A to F. The five dots represent derived characters.

The cladogram supports which of these predictions about the genomes of the six species?

• The genome of species E is equally similar to the genomes of species D and F.

• The genome of species E is more similar to the genome of species F than to any of the other species.

• The genomes of species C and D are nearly identical because neither species has a derived character.

• The genomes of the six species share few, if any, DNA sequences.

Multiple Choice

DeMarco is comparing the bodies of a typical bird and winged insect, as shown in the diagram. 

DeMarco is constructing an argument that the wings of the bird and insect are analogous structures. Which statement provides the STRONGEST evidence for this argument?

• The two types of wings grow and develop from similar or identical embryonic tissues.

• The two types of wings grow and develop from different embryonic tissues.

• The two types of wings have different shapes and sizes.

• The two types of wings are covered in different materials.

Multiple Choice

Darwin developed and proposed the Theory of Evolution during the 1800s. Since that time, due in part to advances in technology, scientists have expanded their knowledge and ideas about biological systems. Which statement describes an example of evidence acquired in the past 100 years and its relationship to the Theory of Evolution?

• New evidence from molecular biology provides overwhelming support that all life evolved from a single ancestor.

• New evidence from molecular biology provides evidence that life evolved from many ancestors, not a single ancestor.

• New evidence from fossils provides evidence that one species does not descend from another.

• New evidence from biogeography provides evidence that one species does not descend from another.

Multiple Choice

Bats and birds are often cited as an example of convergent evolution. Which statement explains this example?

• Wings evolved in a common ancestor of bats and birds.

• Vertebrae evolved in a common ancestor of bats and birds.

• Flight evolved separately and independently in the ancestral lineages of bats and birds.

• Bats are classified in a clade with other mammals, while birds are classified in a clade with reptiles.

Multiple Choice

Wolbachia pipentis is a species of bacteria that infect fruit flies. When the genome of the fruit fly was sequenced, it was found that most of the genome of the bacteria had been integrated into the fruit fly genome.

Describe what has happened between these two organisms.

• This passing of genes between organisms of different species is caused by mutations. This type of gene transfer can increase genetic variation only, if it happens in the cells that produce eggs and sperm.

• This passing of genes between organisms of different species is called gene recombination and happens during sexual reproduction. This type of gene transfer has no effect on genetic variation.

• This passing of genes between organisms of different species is caused by gene duplications. This type of gene transfer can increase genetic variation, if the duplicated genes acquire new functions.

• This passing of genes between organisms of different species is called lateral gene transfer. This type of gene transfer can increase genetic variation, and therefore diversity.

Multiple Choice

A plant called a heliconia has flower parts that form an unusual curved shape. Vera claims that the evolution of the flower shape is an example of coevolution. Which of the following observations would provide the STRONGEST evidence in support of Vera's claim?

• A plant that is not closely related to heliconia also has flower parts that form a curved shape. 

• A recent ancestor of the heliconia had flower parts that formed a more common shape.

• Close relatives of the heliconia have flower parts that form curved shapes.

• Bats are classified in a clade with other mammals, while birds are classified in a clade with reptiles.

Multiple Choice

Which of the following observations is most likely to be explained by the concept of coevolution?

• The bright-red color of male cardinals attracts female cardinals.

• Markings on flower petals attract bees that pollinate the flower.

• A dog learns to run toward the sound of a can opener, which generally precedes feeding time.

• An insect lays thousand of eggs at once, only a few of which will develop into adults.

Multiple Choice

When is adaptive radiation most likely to occur, and for what reason?

• after a mass extinction, because the survivors give rise to species that fill new niches

• just before a mass extinction, because species are competing intensely for limited resources

• when the climate is warmest, because high temperatures act to increase the rate of evolutionary change

• when the climate is stable, because a stable environment tends to decrease the rate of evolutionary change

Multiple Choice

Cory states the following argument about the evolution of aardvarks and anteaters.

"Aardvarks and anteaters both use long, sticky tongues to capture and eat ants or termites. Aardvarks are native to Africa, while anteaters are native to the Americas. However, their similarities provide evidence that both groups of species evolved from a common ancestor that used its tongue to eat ant-like insects."

Which claim, if supported by evidence, would provide the strongest counter-argument AGAINST Cory's argument?

• The tongues and diet of aardvarks and anteaters are an example of convergent evolution.

• The tongues and diet of aardvarks and anteaters are an example of adaptive radiation.

• The Americas and Africa were once joined together, and animals roamed freely between the two lands.

• A long, sticky tongue evolved in response to the tunneling behavior of ants, an example of coevolution.

Multiple Choice

Giraffes, camels, and horses share some traits, although they vary in other traits. Which statement accurately describes the evolution of these species?

• Each species descended from an ancient common ancestor.

• All three species evolved from three unrelated ancient ancestors.

• Each species evolved uniquely, without any ancestors.

• Two of the species descended from the other species.

Multiple Choice

Charles Darwin applied a wide variety of observations to help him develop his ideas about evolution. Which general statement describes several of the observations that Darwin made and considered, and later incorporated into his Theory of Evolution?

• Species may vary from place to place, but most species are distributed widely on all continents.

• Fossils show that ancient species were identical or nearly identical to modern species.

• All species use DNA to carry and translate genetic information.

• Species on islands tend to resemble mainland species, yet differ from them in many ways.

Multiple Choice

Scientists before Darwin had proposed that living things could change over time. Why was Darwin's theory of evolution more powerful and useful than the proposals of the other scientists?

• Darwin explained the mechanism by which evolution occurred.

• Darwin cited examples from nature that were based on observations.

• Darwin used logical reasoning to argue that living things could change.

• Darwin hypothesized that evidence from DNA and genes would explain how evolution occurs.

Multiple Choice

Artificial selection has produced a wide variety of crop plants, livestock, and pets. Which characteristic of artificial selection makes it different from natural selection?

• Humans, not the environment, select which organisms survive and reproduce.

• Adaptations develop gradually over many generations.

• The stock that are reproduced are genetically identical.

• All offspring are allowed to survive and reproduce.

Multiple Choice

A female fish may lay thousands of eggs at once. Which additional statement about fish is most useful for explaining how fish species can evolve by natural selection?

• All of the fish eggs are genetically identical with one another and with the female parent fish.

• The environment cannot support unlimited growth of the fish population, so only some fish eggs will mature to adults.

• After the female fish lays a clutch of eggs, neither parent tends to or cares for the eggs or offspring.

• Fish eggs will develop into embryos only if they are fertilized by sperm from the male fish.

Multiple Choice

Darwin collected and studied a variety of fossils. The fossils provided clues to ancient organisms. As Darwin concluded, how did ancient organisms compare to modern species?

• The ancient organisms were identical to modern species.

• The ancient organisms were larger or smaller than modern species, but otherwise identical.

• The ancient organisms were similar to modern species, but differed in several ways.

• All offspring are allowed to survive and reproduce.

Multiple Choice

The adaptations of a pelican include its long, pouch-like beak. Why is the beak of the pelican an example of an adaptation?

• The beak is a unique feature that is found only in pelicans.

• All birds have beaks, but the beaks vary among different species.

• The shape and structure of the beak have remained the same over many generations.

• The shape and structure of the beak are inherited and help the pelican survive in its environment.

Multiple Choice

A variety of plants and animals live in a meadow ecosystem. According to Darwin's ideas about evolution, which of these meadow organisms has the greatest fitness?

• a snake that eats many mice, and then is eaten by a hawk

• a large, healthy hawk that does not find a mate

• a female mouse that has many offspring

• a lone tree that grows in the middle of the meadow

Multiple Choice

Edwin is studying a population of rabbits in the neighborhood that surrounds his home. He observes a variety of fur colors among the rabbits, including gray, white, and brown. The rabbit fur also has a variety of markings, including spots and bands.

Edwin argues that natural selection will occur on the rabbit population. It will result in a change in the distribution of fur colors and markings.

Which observation would provide the STRONGEST evidence in support of Edwin's argument?

• Neighborhood plants can support a large increase in the rabbit population.

• Fur color and markings do not affect the running speed of a rabbit.

• A new predator tends to hunt more white rabbits than gray or brown rabbits.

• Most of the rabbits are wildlife, while some are pets.

Multiple Choice

A population of male and female goats is stranded on a large island. The goats differ from one another in several ways, including fur color, ear shape, and preferred food.

A scientist predicts that the average ear shape of the goats will change gradually over time. According to Darwin's ideas about evolution and natural selection, the accuracy of the prediction depends on which of these conditions?

• Certain ear shapes allow the goats to hear a wider variety of sounds.

• Certain ear shapes help the goats survive and reproduce on the island.

• The island provides enough food to support an increase in the goat population.

• The hip and shoulder bones in each of the three species are examples of analogous structures.

Multiple Choice

On his visit to the Galapagos Islands, Darwin observed a variety of similar birds that lived either on the ground or in trees. Later, experts classified these birds as finches. Darwin had identified 14 distinct finch species, each different from one another and different from finch species that lived on the mainland.

The diagram shows four of the Galapagos finches, each of which has a different type of beak. The insets compare the beaks to a type of tool.

According to Darwin's theory of evolution, each beak shape is the result of the process of natural selection. Which statement is MOST USEFUL for explaining why different beak shapes evolved in each of the four finch species?

• The food supply selected for beak shape as the finch species descended from a common ancestor.

• The common ancestor of the finch species displayed the same four beak shapes of its descendants.

• Ancestors of the finch species mated with other bird species that had variable beak shape.

• Each finch species evolved from a different ancestor, each with a unique beak shape.

Multiple Choice

A scientist suggests that the first finch species to arrive on the Galapagos Islands was an insect-eating finch, similar to the modern warbler finch (Certhidea olivacea). If the scientist’s suggestion is correct, then how many of the four finch species shown in the diagram could have evolved from the first finch species?

• 1 of the 4 species

• 2 of the 4 species

• 3 of the 4 species

• Fish eggs will develop into embryos only if they are fertilized by sperm from the male fish.

Multiple Choice

Populations of two species of grasshoppers are introduced to a meadow ecosystem. Each species is adapted to eat grass and similar plants of the meadow, and they fill the same niche. According to Darwin’s ideas about competition, which of the following changes is most likely to occur?

• Only one population will thrive in the meadow; the other population will decrease to zero.

• Either both populations will thrive in the meadow or neither population will thrive there.

• Both populations will eventually remain constant at the same nonzero number.

• Both populations will eventually remain constant, but at different nonzero numbers.

Multiple Choice

A population of a species of butterfly is released on a tropical island. Which of the following conditions is necessary for evolution by natural selection to alter the butterfly population over time?

• genetic variation among the members of the population

• a lack of competitors for food, water, and other resources

• relatively stable weather on the tropical island

• genetic uniformity among the members of the population

Multiple Choice

Darwin developed a concept called geographic isolation to explain how species developed. Which observation below provides the strongest evidence for this concept and Darwin's explanation?

• Species that evolved on an island tend to be identical to species on the mainland and on neighboring islands.

• Species that evolved on an island tend to be different from related species on the mainland and from neighboring islands.

• Fossils show that ancient species differed in many ways from species today.

• The bacteria use circular DNA.

Multiple Choice

Darwin proposed that the Galapagos Islands were settled by a small population of a single species of finches. This species was the ancestor of all the finch varieties that Darwin had observed on the islands. According to the modern theory of evolution, what was the role of mutations and sexual reproduction in this process?

• an island predator killing and eating 50 mice

• Mutations and sexual reproduction increased the genetic variation among the population and allowed new adaptations to evolve.

• Mutations and sexual reproduction increased the genetic variation among the population and determined which adaptations increased fitness.

• Mutations and sexual reproduction decreased the genetic variation among the population, allowing only the most fit to survive.

Multiple Choice

Over the past 80 years, changes have occurred to the bacteria populations that commonly cause infectious diseases. The drug penicillin once killed most of these bacteria. Now, the original form of penicillin kills a very low percentage of the bacteria population.

How does evolution by natural selection explain this change to the bacteria population?

• The bacteria became resistant to penicillin as a side effect of their evolution into more complex, more successful species.

• Repeated use of penicillin selected for bacteria that were resistant to it, and these bacteria passed resistance to penicillin to the next generations.

• The bacteria responded to penicillin in their environment by releasing chemicals that reacted with penicillin and made it less effective.

• The bacteria responded to penicillin in their environment by developing resistance to it and passing the resistance to the next generations.

Multiple Choice

Which statement below best describes the role of mutations in evolution by natural selection?

• Mutations increase the genetic variation within a population, and each of the variants provides an advantage under different circumstances.

• Mutations increase the genetic variation within a population, and some of the variants may provide an advantage to individuals over time.

• Mutations help stabilize the genetic variation within a population, and only one or two variants generally provide an advantage to individuals.

• Mutations help reduce the genetic variation within a population, and thus increase the rate that new adaptations develop.

Multiple Choice

In many animal species, males attract female mates with behaviors such as singing, dancing, or giving a gift. As explained by Darwin’s theory of natural selection, are these behaviors examples of adaptations?

• Yes. They are adaptations because they help animals with high fitness reproduce.

• Yes. They are adaptations because they help animals survive, regardless of whether the animal has offspring.

• No. They are not adaptations because they do not help animals survive in their environment.

• No. They are not adaptations because they evolved by chance, and not by natural selection.

Multiple Choice

Which is an example of evolution by genetic drift, and NOT by natural selection?

• A small population of bark beetles is carried in driftwood to a new island, where the members reproduce rapidly.

• A population of lizards develops longer tongues when their food source changes.

• The bright red feathers of a male cardinal helps it attract a female mate.

• A female frog lays hundreds of eggs in a clutch, but only a few of the eggs hatch and develop into adult frogs.

Multiple Choice

Fifteen iguanas survived a hurricane on a raft of uprooted trees. After a month at sea, they colonized an island. They were the first of their species to arrive there. Evolutionary biologists predict that this group of iguanas could become a new species.

Which statements explain why the iguanas would become a new species? Select two answers.

• The island iguanas fill exactly the same niche on the island as they did before.

• The island iguanas are geographically isolated from the original population.

• The island iguanas evolve through favorable adaptations and natural selection.

• The island iguanas have more genetic variation than the original population.

Multiple Choice

Western and Eastern meadowlarks look very similar and it is difficult to tell them apart, until they sing. Their mating songs are quite different. The Western meadowlark has a melodious song, whereas the song of the Eastern meadowlark sounds more like a whistle. Even though their ranges overlap in the central United States, they do not interbreed and are two different species. How would speciation most likely have occurred in these two species of meadowlarks?

• Reproductive isolation occurred through behavioral isolation.

• Reproductive isolation occurred through temporal isolation.

• Populations were separated through geographical isolation.

• Populations were separated through competition.

Multiple Choice

Robins typically lay four eggs. Four eggs allow the offspring to be well fed, whereas larger clutches may result in malnourished chicks that have a lower chance of survival. Fewer than four eggs per clutch may result in no surviving offspring if the eggs are preyed upon. Which pattern of natural selection most likely acts to keep four eggs the most common clutch size?

Multiple Choice

In a population of goats, both beige-coated and brown-coated goats are better able to blend with the rocky environment than white-coated goats. In this case, the beige and brown coat colors are favored by natural selection over the white color.

Which type of pattern of natural selection would occur in this scenario?

Multiple Choice

Two species of fruit flies whose ranges overlap have different periods of mating activity. Drosophila persimilis breeds early in the morning, while Drosophila pseudoobsura breeds in the afternoon.

Identify the mechanism of isolation between these two species.

• Behavioral isolation: Each species has a courtship pattern that allows males and females to recognize each other.

• Temporal isolation: The species remain separate because the period of most active mating differs.

• Geographical isolation: The species remain separate because they have different breeding sites.

• If amino acids formed in the atmosphere of early Earth, they were the first organic molecules to form there.

Multiple Choice

A population of domesticated sheep becomes stranded on a rocky island. Over many years, the physical traits of the sheep population are altered. Their wool became thicker and darker, their hooves became deeper and sturdier, and their ears became smaller and rounder.

These changes are an example of which process?

• evolution by artificial selection, because the changes in traits are unrelated to fitness

• evolution by artificial selection, because sheep are domesticated animals that were bred by humans

• evolution by natural selection, because the environment influenced the fitness of the sheep

• Some island species arrived naturally, while others were introduced through human activity.

Multiple Choice

A scientist proposes that a certain species of bacteria has an unusually high rate of evolutionary change, allowing them to develop new adaptations relatively quickly. Which observation about the bacteria would most strongly support the scientist’s proposal?

• The bacteria have a high rate of mutation.

• The bacteria have a low rate of mutation.

• The bacteria generally reproduce asexually.

• Mutations and sexual reproduction decreased the genetic variation among the population, allowing only the most fit to survive.

Multiple Choice

A population of warblers lives in a forest. Which of these events would cause an evolutionary change in the warbler population, yet most likely does not involve natural selection?

• A mutation introduces a new, advantageous trait to the warbler population.

• A forest fire kills about one third of the warbler population.

• The removal of a predator allows the warbler population to increase.

• The introduction of a new competitor causes the warbler population to decrease.

Multiple Choice

A team of scientists is studying a population of lizards. The team reports that very short lizards tend to be caught and eaten, while very long lizards tend to become weak and listless when they cannot find enough food. Medium-length lizards have neither of these problems, and they tend to live longer and remain healthier than the shorter and longer lizards.

Which prediction about the lizard population is most strongly supported by the scientists’ report? Assume that body length in lizards is inherited as a polygenic trait.

• The population will experience stabilizing selection, but a variety of lizard lengths will still appear in the population.

• The population will experience stabilizing selection, and eventually all the lizards will be medium length.

• The population will experience directional selection, causing medium-length lizards to become more common.

• The population will experience disruptive selection, causing medium-length lizards to become more common.

Multiple Choice

A population of mice lives on an island in the Pacific Ocean. From year to year, the size of the adult population remains at about 300 individuals, and the variety and frequency of the traits of the mice change very little.

Which of these events would be most likely to cause an evolutionary change to the mouse population on the island?

• an island predator killing and eating 50 mice

• a storm that drowned about 50 mice all across the island

• a mutation in the skin cells of an adult mouse

• a drought that reduced and altered the food supply of the mice