Fossils are most likely to be found in _____________.

A. Volcanic rock.

B. Volcanic archipelagos, such as the Galapagos and Hawaiian Islands.

C. Igneous rock.

D. Sedimentary rock.

E. Glaciers.

D. Sedimentary rock.

Sedimentary rock is formed from layers of minerals that settle out of water. When aquatic life-forms and terrestrial organisms swept into the seas and swamps die, they settle along with the sediments.

Why is it that isolated islands, such as the Hawaiian islands, often have many endemic organisms (found nowhere else)?

A. Islands are inhospitable to organisms from other geographical locations.

B. Islands have unique ecological niches.

C. Immigration and gene flow from other locations results in the evolution of unique species.

D. Organisms evolve in isolation because of the difficulty of genetic exchange with other populations in distant locations.

E. Organisms can reproduce faster on islands.

C. Organisms evolve in isolation because of the difficulty of genetic exchange with other populations in distant locations.

Isolated islands have limited immigration and interaction with species in other locations, which limits gene flow.

An important challenge to tradition (pre-1860) ideas about species was the observation that seemingly dissimilar organisms, such as hummingbirds, humans, and whales, have similar skeletal structures. This most directly suggested to biologists that _______________________.

A. Advantageous changes can be passed along to offspring.

B. Only the best-adapted organisms can survive.

C. The geographical locations of organisms can provide clues to their evolution.

D. Most evolution occurs rapidly following a mass extinction.

E. Dissimilar organisms might have evolved from a distant, common ancestor.

E. Dissimilar organisms might have evolved from a distant, common ancestor.

Similarity in characteristics resulting from a common ancestor is known as homology, and such anatomical signs of evolution are known as homologous structures.

Animals that possess homologous structures probably ________________.

A. Are headed for extinction.

B. Evolved from the same ancestor.

C. Had similar mutations by chance in the past.

D. Are not related.

E. Have increased genetic diversity.

B. Evolved from the same ancestor.

"Homology" refers to similarity attributable to common ancestry.

"Homo"="same."

The bones of the wings of bats are homologous to the bones of the ________ of their ancestors.

A. Brain Case.

B. Front Limbs.

C. Jaws.

D. Ribs.

E. Hind Limbs.

B. Front Limbs.

Similarity in characteristics resulting from a common ancestor is known as homology, and the anatomical signs of evolution are called homologous structures.

The approach to evolution that involves the study of similar structures that appear during the development of different organisms is known as the study of ________________.

A. Cladistics.

B. Comparative Embryology.

C. Biogeography.

D. Molecular Biology.

E. Comparative Anatomy.

B.Comparative Embryology.

This is the study of similar structures appearing during the embryonic development of related organisms.

All known organisms transcribe genetic information to protein molecules via the same genetic code. This finding strongly supports the hypothesis that _________________.

A. The genetic code will never be broken.

B. There is not a single common ancestor for all organisms.

C. Life arose through spontaneous generation.

D. There is only one possible way to encode information in a macromolecule.

E. All organisms are descended from a single common ancestor.

E. All organisms are descended from a single common ancestor.

A common genetic code is overwhelming evidence that all life is related.

Evidence from molecular biology supports the theory of evolution by showing that ________________.

A. Closely related organisms have more similar DNA and proteins.

B. Closely related organisms have similar physical characters.

C. Homologous proteins have arisen separately in many different animal groups.

D. Closely related organisms have similar stages of development.

E. Closely related animal species have similar geographic distributions.

A. Closely related organisms have more similar DNA and proteins.

Evolutionary relationships among species are reflected in their DNA and proteins. If two species have similar libraries of genes and proteins, with sequences of monomers that match closely, the sequences must have descended from a common ancestor.

Biologists have noticed that most human beings enjoy sex. How would they explain this in evolutionary terms?

A. If sex were not enjoyable, the human species would have died out.

B. Only body structures evolve, not behavior, so enjoyment cannot evolve.

C. This was due to a random mutation, so it did not affect evolution.

D. Early humans who enjoyed sex had the most babies.

E. Biologists are baffled by the phenomenon of sex.

D. Early humans who enjoyed sex had the most babies.

This is likely, and so it must be likely that the enjoyment of sex could have a genetic origin.

Assume there are two varieties of mice, brown and gray, living on an island. They are the prey for the hawks on the island. They are distributed through rocky areas in the north part of the island and across the fields in the south part. Which of the following is predicted by natural selection?

A. Because brown mice blend better with the ground and gray mice blend better with the rocks, these are the ones that will be missed by the hawks and the mouse distribution will tend to indicate this.

B. If they stay as a mixed population, they will remain mixed because the two varieties will not interbreed with each other.

C. A mouse population that starts as a random mixture will never adapt to the environment.

D. The hawks will starve to death because they get confused.

E. Hawks find the mice by movement, so it will not matter.

A. Because brown mice blend better with the ground and gray mice blend better with the rocks, these are the ones that will be missed by the hawks and the mouse distribution will tend to indicate this.

The hawks will catch the mice they see best, creating two mouse distributions.

"Differential success in reproduction" is just another way of saying _________________.

A. Natural Selection.

B. Genetic Drift.

C. Recombination.

D. Variation.

E. Mutation.

A. Natural Selection.

Natural selection is differential success in reproduction: the unequal ability of individuals to survive and reproduce.

Which one of the following statements most closely agrees with the theory of evolution by means of natural selection, as put forth by Darwin?

A. Organisms deliberately evolve the structures they need to survive.

B. Only the best-adapted organisms will survive.

C. Organisms better adapted to their immediate environment are most likely to survive and reproduce.

D. Humans arose from chimpanzees.

E. Organisms mutate under unfavorable conditions to become better adapted.

C. Organisms better adapted to their immediate environment are most likely to survive and reproduce.

Success in the struggle for survival is not random but depends in part on the hereditary constitution of the surviving individuals. Those individuals whose inherited characteristics fit them best to their environment are likely to leave more offspring than are less fit individuals.

"Natural selection" and "evolution" are two terms that are sometimes confused, even by freshman biology students. What is the relation between natural selection and evolution?

A. Any phenomenon that causes evolution is natural selection.

B. Evolution is the mechanism of natural selection.

C. They are the same thing.

D. When natural selection is occurring, evolution is not, and vice versa.

E. Natural selection is one of several mechanisms of evolution.

E. Natural selection is one of several mechanisms of evolution.

Modern species evolved from ancestral forms, and natural selection is the main mechanism for this evolution.

In natural selection, ____________ determines which phenotypes are successful.

A. Genetic Drift.

B. Human Intervention.

C. Sample Size.

D. Chance.

E. The Environment.

E. The Environment.

Natural selection occurs through an interaction between the environment and the variability inherent among individual organisms making up a population.

Which of the following is a requirement for natural selection?

A. Low numbers of individuals.

B. Greater numbers of offspring from those that do not survive.

C. Variation in individuals.

D. Non-heritable traits.

E. A long period of time.

C. Variation in individuals.

Variation means that some organisms may be better adapted to their environment than others and thus survive and reproduce with greater frequency.

If members of a population have traits that are both heritable and variable among individuals, then ___________________.

A. Advantageous traits may become more widespread in subsequent generations.

B. No evolutionary change is likely to occur over time.

C. Genes will have no influence on an organism's physical appearance.

D. The environment will have no influence on phenotypes.

E. Only mutations can cause changes over time.

A. Advantageous traits may become more widespread in subsequent generations.

Survival in the struggle for existence is not random, but depends in part on the hereditary constitution of the surviving individuals. Those individuals whose inherited characteristics fit them best to their environment are likely to leave more offspring than are less fit individuals.

When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Today, some 30 years later, a much smaller proportion of these insects die when sprayed. The reason fewer insects are being killed is that ______________________.

A. The original spraying has caused a permanent mutation, giving the insects genetic resistance to the spray.

B. Many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics.

C. Mosquitoes that survive spraying develop an immunity to the insecticide.

D. Over time, evolution produces stronger insects.

E. Mosquitoes are deliberately adapting themselves to this man-made change in the environment.

B. Many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics.

Individuals whose characteristics best fit them to their environment are likely to leave more offspring than are less fit individuals. This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over the generations.

Scientists have warned doctors of the danger of their increasing use of antibiotics (for instance, penicillin) for treating minor illnesses. They are concerned because ______________.

A. The drugs will be metabolized more quickly by our bodies, decreasing their effectiveness.

B. Humans will become tolerant to the effects of drugs.

C. Strains of microorganisms that are resistant to these drugs will increase.

D. Excessive use of these drugs leads to a diminished sensitivity to them.

E. The drugs are not meant to treat minor illnesses and have numerous side effects.

C. Strains of microorganisms that are resistant to these drugs will increase.

A new mutation that happens to be beneficial can increase in frequency in a bacterial population very rapidly. If a single individual in the population harbors a mutation that renders it resistant to an antibiotic, there may be millions of resistant bacteria a few hours after antibiotic treatment.

One conclusion that can be drawn from predator-prey studies such as the shrike and its prey, the flat-tailed horned lizard, is ________________.

A. Individuals can evolve.

B. Horns are used only for defense.

C. Evolution is independent of genetics.

D. Any species will prey on flat-tailed horned lizards.

E. Evolution is actually observable and measurable in the world around us.

C. Evolution is actually observable and measurable in the world around us.

Contrary to some misconceptions, evolution is not merely observable in historical records such as fossils.

Similar to the branching pattern of a tree, the fork of an evolutionary tree indicates a(n) _________ of all species emanating from that fork.

A. Extinction.

B. Descendent.

C. Homology.

D. Analogy.

E. Common Ancestor.

E. Common Ancestor.

Everything that emanates from a fork on an evolutionary tree is a descendent of an ancestral species at the fork.

According to the modern synthesis of evolutionary theory, which of the following is true?

A. Segregation and independent assortment explain evolution of the individual and not the species.

B. Evolution is independent of genetics.

C. Only certain animal species are sexual.

D. Individuals can pass on non-heritable traits.

E. Populations are the units of evolution.

E. Populations are the units of evolution.

This is a basis of modern evolutionary thought.

A population is _____________.

A. A group of individuals of the same species occupying a given area.

B. The number of organisms in a particular habitat.

C. The number of humans per unit area.

D. All living organisms on Earth.

E. Organisms of different species that live together.

A. A group of individuals of the same species occupying a given area.

A population is a localized group of individuals belonging to the same species.

The smallest unit that can evolve is a __________.

A. Species.

B. Gene.

C. Genotype.

D. Morph.

E. Population.

E. Population

Populations, the simplest units of organization that exhibit variation, are acted on by the environment and can therefore evolve.

What is the term for a change in the relative frequencies of alleles in a population over several generations?

A. Microevolution.

B. Reservoir.

C. Independent Assortment.

D. Gene Pool.

E. Macroevolution.

A. Microevolution.

Microevolution is a generation-to-generation change in alleles.

Members of the same population __________.

A. Cannot interbreed under natural conditions.

B. Are interbred.

C. Share the same genotype.

D. Share a common gene pool.

E. Are in reproductive isolation from one another.

D. Share a common gene pool.

A population is a group of interbreeding individuals belonging to the same species.

The major weakness of Darwin's theory (as it existed in 1859) was that it could notexplain ____________.

A. Why different parts of the world have different plants and animals.

B. The evolution of a new species.

C. Why vestigial structures exist.

D. How advantageous traits can be passed to offspring.

E. Why species become extinct.

D. How advantageous traits can be passed to offspring.

Darwin was unable to account for the genetics of variation.

The original source of all genetic variation is _______.

A. A need for new traits.

B. Mutation.

C. Meiosis.

D. Recombination.

E. Natural Selection.

B. Mutation.

Mutation is, in itself, very important to evolution because it is the original source of the genetic variation that serves as the raw material for evolution.

Bacteria can adapt to changes in the environment by means of mutation alone because __________.

A. Their populations are very isolated from one another.

B. Their populations are so large.

C. A bacterium is much more likely to mutate than a larger organism.

D. They are so small.

E. They multiply so rapidly.

E. They multiply so rapidly.

This means that more mutations can occur in a given period of time, and it increases the chances that a beneficial mutation will result.

Each of us is part of the ongoing evolution of the human species. Which of the following occurrences would have the greatest impact on the future biological evolution of the human population?

A. You work out every day so that you stay physically fit and healthy.

B. You move to Hawaii, the state with the longest life expectancy.

C. A mutation occurs in one of your sperm or egg cells.

D. You encourage your children to develop their intellectual abilities.

E. A mutation occurs in one of your skin cells.

C. A mutation occurs in one of your sperm of egg cells.

However, considering the huge size of the human gene pool, it probably won't have much of an impact.

Critics like to point out that the theory of evolution is flawed because it is based on random changes: mutations. they say that a random change in an organism (or a car or a TV set) is likely to harm it, not make it function better. What logical statement refutes these critics?

A. This is a weak spot in the theory that remains to be worked out.

B. Mutations are not random.

C. Mutation has little to do with evolution.

D. Mutation is random; natural selection is not.

E. Fossils prove without a doubt that mutations drive evolution.

D. Mutation is random; natural selection is not.

Natural selection results in those best suited to the environment producing the most offspring.

In the Hardy-Weinberg formula, p2 represents ________.

A. The total alleles in the gene pool.

B. All of the possible phenotypes in the gene pool.

C. The frequency of homozygous dominants in the gene pool.

D. The frequency of homozygous recessives in the gene pool.

E. The frequency of heterozygous dominants in the gene pool.

C. The frequency of homozygous dominants in the gene pool.

p = the frequency of the dominant allele (A); thus p2 represents the frequency of homozygous dominants. (AA: p x p = p2).

In the Hardy-Weinberg theorem, 1 represents _______.

A. The frequency of homozygous dominants in the gene pool.

B. The frequency of heterozygous dominants in the gene pool.

C. The frequency of homozygous recessives in the gene pool.

D. The sum of all frequencies of all the alleles of a particular gene that exists in a gene pool.

E. All the possible phenotypes in the gene pool.

D. The sum of the frequencies of all the alleles of a particular gene that exists in a gene pool.

Regardless of the percentages of different alleles, they must always add up to 100%.

Suppose that, with regard to a particular genetic locus with two alleles, A and a, we know that 60% of the alleles in the gene pool of a particular large population are A. Suppose further that we observe this population for five generations, during which we know that no mutation, selection, or migration has occurred. After this period, the frequency of the a allele is expected to be _____.

A. 0.4.

B. 0.16.

C. 0.6.

D. 0.5.

E. 0.25.

A. 0.4

If 60% of the alleles are A, p = 0.6. Because q = 1, the frequency of the a allele must be 0.4. The conditions are compatible with equilibrium, so those frequencies should be maintained.

Approximately one out of every 2.500 Caucasians in the United States is born with the recessive disease cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately how many people are carriers?

A. 1 in 25.

B. 1 in 50.

C. 1 in 10.

D. 96 in 100.

E. 1 in 2,500.

A. 1 in 25.

If q2 equal 1/2,500, then q equals 1/50, p equals 49/50, and 2pq equals approximately 1/25.

If a population is in Hardy-Weinberg equilibrium and remains in equilibrium, which of the following will be true?

A. Asexual organisms will not evolve.

B. Allelic and genotypic ratios will gradually change from one generation to the next.

C. There will be no mutations.

D. The relative frequencies of three genotypes (AA, Aa, aa) will gradually become stabilized at 1.

E. Sexual organisms will evolve.

C. There will be no mutations.

Absence of mutation is a condition of the Hardy-Weinberg equilibrium.

If an earthquake hit a small island so that all but a tiny group of lizards were eliminated and the survivors spread out over the island and the population increased, this would be an instance of __________.

A. Mutation.

B. Gene Flow.

C. The Bottleneck Effect.

D. Nonrandom Mating.

E. The Founder Effect.

C. The Bottleneck Effect.

This is a description of the bottleneck effect.

The evolutionary effects of genetic drift are greatest when __________.

A. Sexual selection occurs.

B. The population size is large.

C. Intra-specific competition is weak.

D. The population size is small.

E. Intra-specific competition is intense.

D. The population size is small.

Changes in the gene pool of a small population are frequently due to genetic drift.

The severe reduction in genetic variability seen in the endangered cheetah is probably attributable to __________.

A. Gene Flow.

B. Having gone through at least one bottleneck.

C. Mutation.

D. Natural Selection.

E. Sexual Selection.

B. Having gone through at least one bottleneck.

Along with reducing the size of a population, a bottleneck reduces genetic variation.

Which of the following is the best example of gene flow?

A. An earthquake results in the formation of a canyon, splitting a population of toads apart.

B. All the mutations in a population were neutral.

C. Genes are shuffled by the crossing over of chromosomes during meiosis.

D. Wind blows pollen from one population of plants to another, and cross-fertilization occurs.

E. A polyploid plant develops.

D. Wind blows pollen from one population of plants to another, and cross-fertilization occurs.

Over several generations, the two populations will become more similar.

A geneticist studied a grass population growing in an area of erratic rainfall and found that plants with alleles for curled leaves reproduced better in dry years, and plants with alleles for flat leaves reproduced better in wet years. This situation would __________.

A. Lead to uniformity in the grass population.

B. Preserve the variability in the grass population.

C. Cause genetic drift in the grass population.

D. Lead to directional selection in the grass population.

E. Cause gene flow in the grass population.

B. Preserve the variability in the grass population.

Both types survive in approximately equal numbers over several years.

Which of the following statements best describes how the process of natural selection works to change allele frequencies?

A. The best-adapted organisms will survive.

B. Allele frequencies will change in response to changes in population size.

C. Beneficial mutations will arise in response to a new environment.

D. The best-adapted organisms will leave behind more offspring.

E. A small population size encourages genetic diversity.

D. The best-adapted organisms will leave behind more offspring.

Natural selection is differential reproductive success, with the most fit individuals contributing disproportionately more offspring to the next generation than do less fit individuals.

In a population of bears, which is most likely to be considered to have the greatest Darwinian fitness?

A. The bear having the largest number of mutations.

B. The strongest, fiercest bear.

C. The biggest bear.

D. The bear that leaves the most descendants.

E. The bear that blends in with its environment the best.

D. The bear that leaves the most descendants.

That is the definition of fitness in the Darwinian sense.

Birds with average-sized wings survived a sever storm more successfully than other birds in the same population with longer or shorter wings. This illustrates __________.

A. Gene Flow.

B. Artificial Selection.

C. The Founder Effect.

D. Stabilizing Selection.

E. Disruptive Selection.

D. Stabilizing Selection.

Stabilizing selection favors the intermediate type.

A population of squirrels is preyed on by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large. What process is responsible for this outcome?

A. Disruptive Selection.

B. Hardy-Weinberg Equilibrium.

C. Stabilizing Selection.

D. Artificial Selection.

E. Directional Selection.

A. Disruptive Selection.

Disruptive selection favors individuals at both ends of the phenotypic spectrum.

In a large population of randomly breeding individuals, the frequency of a recessive allele is initially 0.3. There is no migration and no selection. Humans enter this ecosystem and selectively hunt individuals showing the dominant trait. When the gene frequency is reexamined at the end of the year, ________________________________.

A. The frequency of the homozygous dominants will go down, the frequency of the heterozygous genotype will remain the same, and the frequency of the homozygous recessives will go up.

B. The frequency of the homozygous dominants will go up, the frequency of the heterozygous genotype will go down, and the frequency of the homozygous recessives will go up.

C. The frequency of the homozygous dominants will go up, the frequency of the heterozygous genotype will go down, and the frequency of the homozygous recessives will go down.

D. The frequency of the homozygous dominants will go down, the frequency of the heterozygous genotype will go up, and the frequency of the homozygous recessives will remain the same.

E. The frequency of the individuals who express the dominant phenotype will go down and the frequency of the homozygous recessive individuals will go up.

E. The frequency of the individuals who express the dominant phenotype will go down and the frequency of homozygous recessive individuals will go up.

The frequency of individuals who express the dominant phenotype should decline, and the proportion of individuals who express the recessive phenotype (homozygous recessives) should increase.

Antibiotic resistance in bacteria is an example of which of the following?

A. Stabilizing Selection.

B. Hardy-Weinberg Equilibrium.

C. Directional Selection.

D. Disruptive Selection.

E. Sexual Selection.

D. Directional Selection.

Directional selection favors those individuals at one end of the spectrum that best adapt to a new situation-- in this case, the presence of an antibiotic.

Stabilizing selection ___________________.

A. Can take place only in species exhibiting sexual dimorphism.

B. Occurs only in plants.

C. Favors intermediate variants in a population.

D. Prevents mutations from occurring.

E. Occurs when some individuals migrate to an area with different environmental conditions.

C. Favors intermediate variants in a population.

Stabilizing selection culls extreme variants from the population.

Sexual selection is a form of _____________.

A. Gene Flow.

B. Mating.

C. Gigantism.

D. Natural Selection.

E. Disruptive Selection.

D. Natural Selection.

Sexual selection is a special type of natural selection where mates do the selecting. Because it is a type of natural selection, sexual selection is a mechanism of evolution.

Tay Sachs disease, which is lethal, results from having the homozygous recessive condition of the responsible gene. Which one of the following statements is true?

A. Because homozygous recessive individuals die, the recessive allele will eventually be lost from the population.

B. Heterozygous individuals will survive and be able to pass the recessive allele on to their offspring.

C. Homozygous dominant individuals will be more likely to reproduce than heterozygous individuals.

D. Only homozygous dominant individuals will be able to survive and reproduce.

E. In the heterozygous condition, the dominant allele will overcome the recessive allele and only the dominant allele will be passed on to offspring.

B.

The diploid nature of most eukaryotes hides a considerable amount of genetic variation from selection, in the form of recessive alleles in heterozygotes.