In explaining what we now call evolution, Darwin often used the phrase “descent with modification.” Fundamental to this idea is that
a. species are immutable.
b. natural selection is the primary mechanism of evolution.
c. divergent species share a common ancestor.
d. Earth has been shaped by slow-acting forces that are still at work today.
e. we have knowledge of the genetic basis of evolutionary change.
Mistakes in the replication of DNA
a. occur when an organism requires them.
b. are always repaired.
c. provide genetic variation.
d. are most often beneficial to the individual.
e. are always deleterious to an organism.
Which phenomenon is not an evolutionary mechanism?
a. Mutation
b. Gene flow
c. Genetic drift
d. Random mating
e. Natural selection
Which evolutionary process adapts populations to their environments?
a. Mutation
b. Natural selection
c. Nonrandom mating
d. Gene flow
e. Genetic drift
The frequency of one allele for a given gene locus with two alleles (A at frequency p and a at frequency q) in a population is known. Assume Hardy-Weinberg conditions hold true. Which statement is false?
a. The frequency of heterozygotes is given by (p + q)/N, where N is the number of individuals in the population.
b. There is sufficient information given to calculate the frequency of heterozygotes (Aa).
c. The frequency of a is given by 1 – p.
d. The frequency of A is given by 1 – q.
e. The frequency of a is dependent on that of A.
The frequency of an allele in a population of manatees is 0.15. If the population is at Hardy-Weinberg for this locus, what number of 600 individuals should be homozygous for this allele?
a. 2.25
b. 13.5
c. 27
d. 90
e. 135
The Hardy-Weinberg equilibrium is not applicable under which condition?
a. Random mating
b. Infinite population size
c. No gene flow
d. Asexual reproduction
e. No mutations
You discover a population of seals and find it to be at Hardy-Weinberg equilibrium with respect to the A locus. Suppose that there are two alleles at this locus and the frequency of one of those alleles (the a-6 allele) is 0.4. Of the individuals that carry at least one a-6 allele, what percent are homozygotes?
a. 10
b. 15
c. 25
d. 40
e. 60
Which statement about selection is true?
a. Disruptive selection is the only type of selection that can produce a bimodal distribution.
b. Stabilizing selection increases variation.
c. In directional selection, individuals close to the mean have the highest fitness.
d. Disruptive selection favors individuals close to the mean.
e. Stabilizing selection is the only type of selection that acts on quantitative variation.
_______ selection operates if individuals within a population with the smallest and largest body sizes have fewer offspring than those of average body size.
a. Stabilizing
b. Destabilizing
c. Sexual
d. Directional
e. Disruptive
Suppose the size of a population of mustard plants is 6,000. According to genetic drift theory, what is the probability that a newly-arisen mutation will become fixed in this population?
a. 1/2
b. 1/100
c. 1/3,000
d. 1/6,000
e. 1/12,000
Which statement about synonymous mutations is true?
a. They change the amino acid composition of the protein.
b. They do not change the phenotype.
c. They will affect the structure of the protein.
d. They will likely change the activity of the protein.
e. They will likely be lethal.
A neutral mutation
a. becomes fixed in a large populations more rapidly than in small ones.
b. is subject to strong selection.
c. confers a selective advantage to an organism.
d. is fixed in a population at a rate equal to the mutation rate.
e. confers a selective disadvantage to the organism.
A gene involved in neural development shows three times as many synonymous site substitutions than nonsynonymous ones. A likely explanation is that this gene
a. is under positive selection.
b. is under purifying selection
c. is affected by heterozygote advantage. a neutral gene.
e. has a very high mutation rate.
Which observation would most seriously challenge the hypothesis that most noncoding DNA is slightly deleterious?
a. Species with larger population sizes have more noncoding DNA.
b. Species with smaller population sizes have more noncoding DNA.
c. Species with larger genomes lose DNA more slowly through mutational processes than those with larger genomes.
d. Species with larger genomes lose DNA more quickly through mutational processes than those with smaller genomes.
e. There is an inverse relationship between the total amount of DNA in the genome and the percentage of the DNA that is noncoding.
Which statement about the genomes of organisms is false?
a. Most of the DNA in a bacterium codes for either RNA or protein.
b. The total size of the genome of eukaryotes varies little from organism to organism.
c. There is some correlation between genome size and complexity of the organism.
d. Pseudogenes evolved from functional genes.
e. Noncoding regions of the DNA have higher mutation rates than coding regions.
Sexual recombination
a. increases the overall reproductive rate.
b. can result in the elimination of harmful mutations.
c. decreases the variety of genetic combinations.
d. changes the frequency of alleles in a population.
e. has no influence on evolution.
Gene families are groups of _______ genes that arose by _______ and _______.
a. homologous; speciation; sequence evolution
b. heterologous; gene duplication; sequence evolution
c. homologous; gene duplication; genetic drift
d. heterologous; speciation; genetic drift
e. homologous; gene duplication; sequence evolution
The _______ of a phylogenetic tree represents the common ancestor, the _______ represent events where lineages diverged, and the _______ axis represents time. Assume that the tree is oriented as described in the textbook.
a. node; roots; horizontal
b. root; nodes; horizontal
c. root; nodes; vertical
d. node; branches; vertical
e. root; branches; vertical
A _______ is any group of organisms we name, while a _______ is any _______ that consists of all the evolutionary descendants of a common ancestor.
a. taxon; clade; taxon
b. clade; taxon; sister clade
c. taxon; sister clade; clade
d. taxon; clade; sister clade
e. clade; sister clade; taxon
Which statement about traits is false?
a. A trait may be considered ancestral or derived, depending on the point of reference.
b. Synapomorphies are shared ancestral traits.
c. Derived traits differ from their ancestral forms.
d. Homoplastic traits can arise by convergent evolution.
e. Traits may be lost by evolutionary reversal
The bones in the wings of birds and bats are _______ because they derived from a _______ ancestor, while the wings are _______ traits.
a. homologs; common; nonhomologous
b. homologous; common; homoplastic
c. homoplasies; different; homologous
d. homologous; different; homoplastic
e. homologs; common; homologous
A sea squirt is thought to be more closely related to vertebrates than once thought because
a. both the adult and larval forms of the sea squirt have a notochord.
b. adult sea squirts have a notochord.
c. sea squirt larvae have a vertebral column.
d. both vertebrate embryos and sea squirt larvae have notochords.
e. adult frogs have a notochord.
Three character sets are being considered for inclusion in a phylogenetic analysis of lizards. The first (A) is fossil data on lizards from 10 to 20 million years ago. The second (B) is on a variety of mating behaviors that have been shown to be learned. The third (C) is from a few nuclear genes that have variable rates of evolution. Which is least likely useful to the analysis of phylogenetic relationships, and why?
1) A, because it is fossil data.
2) B, because it involves behavioral data.
3) B, because it involves learned traits.
4) C, because it cannot be put in a maximum likelihood framework.
5) C, because the molecules are evolving at different rates.
The best way to assess the accuracy of methods to reconstruct phylogenetic history is to
a. use maximum likelihood methods.
b. use experimental tests of organisms with known evolutionary histories.
c. use a molecular clock.
d. use sequence genes that evolve at different rates.
e. add fossil data to the analysis.
Phylogenetic analyses of opsin pigments have allowed scientists to infer that ancestral archosaurs
a. could be brought back to life.
b. had a preexisting sensory bias.
c. had yellow eyes.
d. may have been nocturnal.
e. could not see the color blue.
Suppose that mice and humans differ by 30 substitutions in their globin genes, and rats and mice differ by five substitutions. On the basis of other evidence, we know that the ancestor to humans and mice lived 84 million years ago. Assuming the molecular clock is operating, rats and mice split from each other _______ million years ago.
a. 5
b. 14
c. 30
d. 42
e. 70
A molecular clock assumes that the genes used
a. are evolving rapidly.
b. are evolving slowly.
c. are all evolving at the same rate.
d. do not alter their rates in different lineages.
e. alter their rates in different lineages.
The studies of self-incompatible (outcrossing) species of Leptosiphon illustrate
a. how molecular clocks are used in dating past events.
b. how phylogenetic systematics can reveal convergent evolution.
c. how phylogenetic systematics can reconstruct ancestral molecules.
d. biological classification based on phylogenies.
e. that the accuracy of phylogenetic methods can be accessed.
In the classification system devised by Linnaeus, the names of _______ of plants end with the suffix _______, while those of animals end with _______.
a. classes; -idae; -aceae
b. families; -aceae; -idae
c. orders; -idae; -aceae
d. families; -idae; -aceae
e. classes; -aceae; -idae
Which statement about biological classification is false?
a. Taxonomists use biological classification to show evolutionary relationships among organisms.
b. Separate rules for classification have been established by botanists and zoologists.
c. The same binomial name may be given to two different organisms as long as they are in different phyla.
d. Classifications should be monophyletic.
e. A monophyletic group may be removed from a phylogenetic tree with a single “cut.”
A taxon that contains organisms that do not share a common ancestor is referred to as
a. a clade.
b. monophyletic.
c. polyphyletic.
d. homologous.
e. homoplastic.
Ernst Mayr’s biological species concept
a. applies to all organisms.
b. is based only on morphological characters.
c. applies only to animals.
d. applies only to groups of organisms living in the same areas.
e. does not apply to organisms that reproduce asexually
Which statement about the morphological species concept is true?
a. It is easily applicable to cryptic species.
b. It emphasizes the potential to interbreed.
c. It is most applicable when there is variation within species.
d. Linneaus used one.
e. It emphasizes ancestor-descendant relationships.
Which species concept most emphasizes the evolutionary history of species?
a. The morphological species concept
b. Mayr’s biological species concept
c. The lineage species concept
d. The cryptic species concept
e. The polyploidy species concept
The Dobzhansky-Muller model
a. is based on the morphological species concept.
b. emphasizes gene interaction.
c. cannot be applied to chromosomal rearrangements.
d. is an explanation for the origin of physical barriers that separate species.
e. cannot be applied to cryptic species.
In the Dobzhansky-Muller model, an ancestral population (aabb) splits into two lineages. Different mutations produce different new alleles in each population (Aabb in one population, aaBb in the other). All of the following genotypes would be viable except
a. aabb.
b. Aabb.
c. aaBB.
d. AaBb.
e. aaBb.
All of the following statements about speciation are true except
a. evolution always results in speciation.
b. gene flow within a population must be interrupted for speciation to occur.
c. the Dobzhansky-Muller model is based on a minimum of two gene loci.
d. chromosomal rearrangements can lead to speciation.
e. reproductive isolation may take millions of years.
Which of the following is least likely to lead to allopatric isolation?
a. A river dividing a population of small crickets
b. A small lake dividing a population of butterflies
c. A hill dividing a population of desert-dwelling mice
d. A deep gorge dividing a population of slow-moving snails
e. A land bridge dividing a population of tuna
Geographic isolation
a. always results in reproductive isolation.
b. always results in the formation of new species.
c. is required for speciation.
d. may decrease the probability, over time, that members of two separated populations can mate.
e. has the same effects on all organisms.
Which sequence of events is most likely in allopatric isolation?
a. Geographic barrier, reproductive isolation, genetic divergence
b. Geographic barrier, genetic divergence, reproductive isolation
c. Genetic divergence, geographic barrier, reproductive isolation
d. Genetic divergence, reproductive isolation, geographic barrier
e. Reproductive isolation, genetic divergence, geographic barrier
Darwin’s finches on the Galapagos Islands have diverged primarily via _______ speciation, and exhibit diverse morphologies owing to differences in ________.
a. allopatric; predation pressures
b. allopatric; drought tolerance adaptations
c. allopatric; their diets
d. sympatric; predation pressures
e. sympatric; their diets
A butterfly is separating into two different groups—one that lays eggs in the understory of bushes and the other that lays eggs in the tops of bushes. This butterfly species is most likely experiencing
a. allopatric speciation.
b. speciation due to directional selection.
c. sympatric speciation.
d. the formation of new species by polyploidy.
e. the early stages of extinction.
Which statement about polyploidy in plants is true?
a. Polyploidy is rare in plants.
b. Allopolyploids are hybrid plants that result from the mating of two closely related species.
c. Tetraploid plants can mate with other tetraploid plants of the same species, but not with themselves.
d. Tetraploid and diploid plants of a given species can mate to produce viable triploid offspring.
e. Polyploid plants are usually less vigorous than diploid plants of the same species.
The distinction between prezygotic and postzygotic isolation is whether
a. the isolation occurs before or after fertilization.
b. the isolation occurs before or after mating.
c. reinforcement is involved.
d. selection directly favors the reproductive isolation.
polyploidy is involved.
Two geographically separated populations of butterflies begin to diverge in the time of day they are active. One group is active earlier in the day, and the other is active later. If this separation were to continue, it would most likely contribute to _______ isolation.
a. behavioral
b. mechanical
c. gametic
d. temporal
e. habitat
Prezygotic isolating mechanisms can arise from all of the following except
a. evolution of the structure of sexual organs.
b. specific interactions of plants with insect pollinators.
c. mate selection behaviors.
d. low fertility of hybrids.
e. differences in mating periods.
Suppose that the natural ranges of horses and donkeys were to overlap. Which of the following statements best describes what would likely happen to the populations over time?
a. The hybrid offspring (mules) would become widespread and mate with members of both populations.
b. The hybrid offspring would mate with other hybrid offspring to produce viable offspring.
c. Because their hybrid offspring are not reproductively fit, reinforcement could strengthen postzygotic barriers.
d. Eventually, all members of both populations would be hybrids.
e. Because their hybrid offspring are not reproductively fit, reinforcement could strengthen prezygotic barriers.
Two populations that were once isolated come into contact. Which of the following statements about what might happen after contact is false?
a. If hybrids are unfit, reinforcement of prezygotic barriers would be disfavored.
b. If reproductive isolation is not complete, the two populations could interbreed.
c. Hybrids, if fit, could spread through both populations, resulting in gene flow between them.
d. If reproductive isolation had been established before contact, the two populations could not interbreed.
e. Hybrid zones that last for long periods of time could develop.
Which is least likely to evolve via direct natural selection?
a. Temporal isolation
b. Mechanical isolation
c. Hybrid infertility
d. Behavioral isolation
e. Habitat isolation
Persistent hybrid zones, like those found in Bombina frogs in Europe, stay narrow due to
a. low hybrid adult viability.
b. hybrid infertility.
c. habitat isolation.
d. behavioral isolation.
e. temporal isolation.
For which population would density best be measured per unit of volume, instead of per unit of area?
a. Mustard plants off the coast of Sweden
b. Deer living in a forest in Vermont
c. Earthworms in the soil in Pennsylvania
d. Baboons in Kenya
e. Wild tomato plants in Mexico
You know that the population density of rabbits in an area is 80 individuals per square kilometer. The birth rate is 0.04 per week, and the death rate is 0.03 per week. From this information, population size would be calculated by
a. subtracting the carrying capacity from 80.
b. multiplying the occupied area by 80.
c. dividing 80 by the birth rate.
d. dividing the occupied area by 80.
e. subtracting the death rate from the birth rate, then multiplying by 80.
In a population of 400 deer, the per capita birth rate is 0.16 per year and the per capita death rate is 0.22 per year. In the following year, you would expect a(n) _______ of _______ deer in this population.
a. increase; 64
b. increase; 24
c. decrease; 64
d. decrease; 88
e. decrease; 24
There are 300 individuals in a population at time x. During the next month, 60 individuals are born and 30 die. What is the per capita growth rate per month?
a. -0.2
b. -0.1
c. 0.1
d. 0.2
e. 0.3
If b, the per capita birth rate, is higher than d, the per capita death rate, which of the following is most likely to occur?
a. The population will grow because r ; 0.
b. The population will go extinct because r = 0.
c. The population will grow because r ; 0.
d. The population stays the same because r = 0.
e. The results cannot be determined from the information provided.
The survivorship of five-year-old foxes is 0.34. The fecundity of these foxes is 0.54. What is the mortality of five-year old foxes?
a. 0.34
b. 0.46
c. 0.54
d. 0.66
e. 0.88
You are experimenting with sunflower photosynthetic rates. You expose different plants to different light intensities, ranging from no light to full sun. What type of relationship would you expect to see between increasing light intensity and rate of photosynthesis?
a. The rate of photosynthesis would be equal at all light levels.
b. The rate of photosynthesis would increase with no limit.
c. The rate of photosynthesis would decrease with no limit.
d. The rate of photosynthesis would increase but eventually level off.
e. The rate of photosynthesis would decrease but eventually level off.
The principle of _______ states that once an organism has acquired a unit of some resource, that bit of resource cannot be used for multiple functions at once.
a. allocation
b. tradeoffs
c. survivorship
d. density dependence
e. the carrying capacity
Which population cannot survive indefinitely?
a. One with a per capita growth rate of 0.02
b. One with a per capita birth rate of 0.13 and a per capita death rate of 0.11
c. One with a per capita birth rate of 0.05 and a per capita death rate of 0.08
d. One with a per capita birth rate of 0.04 and a per capita death rate of 0.02
e. One with a per capita growth rate of 0.05
A hypothetical population not constrained by environmental limits would experience _______ growth.
a. multiplicative
b. additive
c. divisive
d. subtractive
e. no
The number of individuals of any particular species that can be supported by a particular environment is known as
a. a metapopulation.
b. survivorship.
c. the carrying capacity.
d. the organismal capacity.
e. a closed system.
An exponentially growing population of skunks has a doubling time of 10 years. In 2013 it had a population of 3,000. If it continues to grow at this rate, the population size will be _______ in the year 2033.
a. 3,000
b. 6,000
c. 9,000
d. 12,000
e. 24,000
At carrying capacity, r is
a. positive and very high.
b. positive and low.
c. zero.
d. negative and low.
e. negative and very high.
The current human population per capita growth rate is
a. positive, and higher than it has ever been.
b. positive, but lower than it was in 1963.
c. essentially zero.
d. negative, but increasing toward zero.
e. negative, and becoming more negative.
The set of subpopulations in an area make up a(n)
a. metapopulation
b. open system.
c. dispersal corridor.
d. BIDE.
e .carrying capacity.
The difference between the BD growth model and the BIDE model is the inclusion of _______ in the BIDE model.
a. density-dependent growth
b. death and carrying capacity
c. inbreeding and evolution
d. immigration and emigration
e. natural selection and immigration
By necessity, in the BD model (not the BIDE model), populations are considered to be
a. at carrying capacity.
b. closed systems.
c. open systems.
d. reliant on dispersal corridors.
e. increasing.
Fishermen prefer to catch _______ rockfish, and this has led to a(n) _______ in the size of rockfish.
a. larger; increase
b. larger: decrease
c. female; increase
d. smaller; increase
e. smaller; decrease
The most effective way to reduce the number of ticks that cause Lyme disease in an area would be to _______ the number of _______.
a. increase; deer
b. decrease; deer
c. decrease; small mammals
d. increase rockfish
e. decrease rockfish
If two organisms use the same resources and those resources are insufficient to supply their combined needs, the organisms’ interactions constitute
a. amensalism.
b. mutualism.
c. commensalism.
d. predator-prey.
e. competition.
Predation is the type of interaction in which
a. one participant is harmed while the other benefits.
b. one participant is harmed but the other is unaffected.
c. one participant benefits and the other is unaffected.
d. two organisms use the same limited resources.
e. both participants benefit.
Mutualism is the type of interaction in which
a. one participant benefits and the other is unaffected.
b. two organisms use the same limited resources.
c. one participant is harmed and the other benefits.
d. one participant is harmed but the other is unaffected.
e. both participants benefit.
Commensalism is the type of interaction in which
a. one participant benefits and the other is unaffected.
b. two organisms use the same limited resources.
c. one participant is harmed while the other benefits.
d. one participant is harmed but the other is unaffected.
e. both participants benefit.
Guppies (fish) swimming in a stream disrupt the growth of algae without any effect on the fish. This relationship can best be described as
a. predation.
b. parasitism.
c. competition.
d. commensalism.
e. amensalism.
If you set up an experiment pairing different species of Paramecium together, under what circumstance would one species be least likely to go extinct?
a. Consumer-resource interaction
b. Interspecific competition
c. Amensalism
d. Mutualism
e. Intraspecific competition
A population of plants has a per capita growth rate of -0.12 per year. The presence of a mutualistic aphid increases this rate by 0.002 per aphid per square meter. Keeping the per capita growth rate of the plant above zero requires a _______ density of aphids of _______ per m2.
a. maximal; 59
b. maximal; 239
c. minimal; 7
d. minimal; 61
e. minimal; 241
At low densities and in the absence of any other beetle species, the population of a strain of the flour beetle Tribolium castaneum grows at a per capita rate of 0.3 per week. In controlled lab conditions, the per capita growth rate is reduced by 0.015 for every 100 individuals. The addition of a related beetle, Tribolium freemani, further reduces the per capita growth rate of T. castaneum by 0.02 for every 100 T. freemani individuals. If there are 800 T. castaneum and 500 T. freemani individuals, what is the per capita growth rate of the T. castaneum population?
a. -0.22
b. -0.1
c .0.08
d. 0.18
e. 0.52
Which factor is most likely to promote the coexistence of competing species via rarity advantage?
a. Interspecific competition being stronger than intraspecific competition
b. Interspecific competition being weaker than intraspecific competition
c. Frequent trophic cascades
d. Rare trophic cascades
e. The Muir effect being stronger than intraspecific competition
In a mythical world, Kelters eat Fygons and Joosts. Joosts are autotrophs, while Fygons eat autotrophs. Based on this information you would conclude that Kelters are
a. primary producers.
b. primary consumers.
c. carnivores.
d. herbivores.
e. omnivores.
Which statement about primary consumers is true?
a. They are decomposes.
b. They eat carnivores.
c. They eat herbivores.
d. They are herbivores.
e. They do not eat any organisms.
The Muir effect
a. expresses the idea that different components of food webs are often interdependent.
b. states that mutualists help other species for altruistic reasons.
c. states that mutualists help other species because it is in their own best evolutionary interests to do so.
d. explains the pervasive nature of evolutionary arms races.
e. explains why some competing species can coexist, while others cannot.
Species introduced to regions outside their original range that then spread widely and become abundant at a cost to the native species of the region are known as _______ species.
a. endemic
b. fragmented
c. invasive
d. exotic
e. parasitic
Defensive strategies are most likely to evolve in
a. the consumer of a consumer-resource relationship.
b. the resource of a consumer-resource relationship.
c. both species in a mutualism.
d. only one species in a mutualism.
e. commensalisms.
A plant species produces a chemical that is toxic to herbivores. Over time, herbivores that can detoxify the chemical increase in frequency. A mutation in the plant produces a new, different toxic chemical that the herbivores cannot detoxify. This is an example of
a. a mutualism.
b. resource partitioning.
c. an evolutionary arms race.
d. commensalism.
e. amensalism.
Which relationship is most likely to lead to resource partitioning?
a. Mutualism
b. Interspecific competition
c. Intraspecific competition
d. Amensalism
e. Predation
Trading of goods and/or services between individuals of different species
a. is called altruism.
b. is most likely to be found in consumer-resource relationships.
c. is most likely to be found in mutualisms.
d. does not exist in nature.
e. must involve at least three trophic levels.
Which statement about mutualisms is false?
a. They involve conflicts of interests.
b. They involve biological barter.
c.Both species benefit.
d. They are highly stable.
e. Diverse types exist.

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