Bio 1202 exam 1

Rabbit ear size tends to decrease as latitude increases. This is an example of _____. A) heterozygote advantage B) a cline C) polymorphism D) artificial selection E) genetic drift

B

Which variable is likely to undergo the largest change in value resulting from a mutation that introduces a new allele into a population at a locus for which all individuals formerly had been fully homozygous? A) average number of loci B) average heterozygosity C) geographic variability D) nucleotide variability

B

**figure 7** A hypothetical population of 500 cats has two alleles, T and t, for a gene that codes for tail length. (T is completely dominant to t.) The table below presents the phenotype of cats with each possible genotype, as well as the number of individuals in the population with each genotype. Assume that this population is in Hardy-Weinberg equilibrium. Recall that the Hardy-Weinberg equation is p 2 + 2pq +q 2 = 1 1. what is the frequency of cats with long tails in the population? 2. what is the frequency of cats with short tails in the population? 3. what is the frequency of cats that are homozygous dominant in the population? 4. what is the frequency of the T allele in the gene pool of this population? 5. what is the frequency of the t allele in the gene pool of this population? 6. use the hardy-weinberg equation to predict the frequency of heterozygous cats in the next generation 7. use the hardy-weinberg equation to predict the frequency of homozygous recessive cats in the next generation 8. use the hardy-weinberg equation and your answer to question 7 to estimate the frequency of the recessive allele t in the next generation

1. 0.84 2. 0.16 3. 0.36 4. 0.60 5. 0.40 6. 0.48 7. 0.16 8. 0.40

**figure 1** Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta and a third extant species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree? (The length of the branches reflects evolutionary time.)

A

The evolutionary effects of genetic drift are greatest when _____. A) the population size is small B) intraspecific competition is weak C) intraspecific competition is intense D) the population size is large E) sexual selection occurs

A

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the estimated frequency of allele A in the gene pool? A) 0.50 B) 0.125 C) 0.25 D) 0.75

A

Genetic drift is a process based on _____. A) the role of chance B) emigration C) differential reproductive success correlated to the relationship between a phenotype and the environment D) immigration E) mutation

A

Homologous pairs of chromosomes are lined up independently of other such pairs during _____. A) metaphase I B) metaphase II C) telophase II D) anaphase I E) prophase II

A

In 1959, doctors began using the powerful antibiotic methicillin to treat infections of Staphylococcus aureus, but within two years, methicillin-resistant strains of S. aureus (MRSA) appeared. How did the resistant strains of S. aureus emerge? A) Staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common. B) In response to treatment of Staphylococcus aureus infections with methicillin, some bacteria began to synthesize cell walls using a protein that was not affected by methicillin. These bacteria survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common. C) In response to treatment of Staphylococcus aureus infections with methicillin, bacterial populations gradually began to synthesize cell walls using a protein that was not affected by methicillin.

A

In human gamete production there is an average of _____ crossover events per chromosome pair. A) 2-3 B) 10+ C) 0-1 D) 5-6 E) 9-10

A

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

A

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

A

What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals? A) 0.4 B) 80 C) 0.1 D) 0.5

A

Which of the following evolutionary forces could create new genetic information in a population? A) Mutation B) Selection C) Genetic drift D) Nonrandom mating

A

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

A

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained? A) Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency. B) A patient must have become infected with MRSA from another community. C) In response to the drug, S. aureus began making drug-resistant versions of the protein targeted by the drug. D) S. aureus can resist vaccines. E) The drug caused the S. aureus DNA to change.

A

**figure 8** A hypothetical population of 200 cats has two alleles, TL and TS, for a locus that codes for tail length. The table below describes the phenotypes of cats with each possible genotype, as well as the number of individuals in the population with each genotype. Which statements about the population are true? Select the five statements that are true. A) Heterozygotes make up 20% of the population. B) Homozygotes make up 80% of the population. C) Homozygotes make up 30% of the population. D) In the entire cat population, 60% of the alleles are TS. E) In the entire cat population, the frequency of the TS allele is 0.5. F) In the entire cat population, the frequency of the TL allele is 0.4. G) Assuming random mating, each gamete has a 50% chance of having a TL allele and a 50% chance of having a TS allele. H) Assuming random mating, each gamete has a 40% chance of having a TL allele and a 60% chance of having a TS allele.

A, B, D, F, H

Considering the same population of cats as in Part A, what is the expected frequency of each genotype (TLTL, TLTS, TSTS ) based on the equation for Hardy-Weinberg equilibrium? Keep in mind that you just learned in Part A that: The allele frequency of TL is 0.4. The allele frequency of TS is 0.6. The equation for Hardy-Weinberg equilibrium states that at a locus with two alleles, as in this cat population, the three genotypes will occur in specific proportions: p2+2pq+q2=1 **figure 9 A? B? C?

A. .16 B. .48 C. .36

**figure 2** The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (VZ) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five common ancestors, labeled VZ, has been least successful in terms of the percent of its derived species that are extant? A) V B) W C) X D) Y E) Z

B

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What proportion of the population is probably heterozygous (Aa) for this trait? A) 0.25 B) 0.50 C) 0.75 D) 0.05

B

According to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if _____ is the only process that affects the gene pool. A) sexual selection B) sexual reproduction C) mutation D) genetic drift E) immigration

B

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that A) convergent evolution led to the DNA similarities. B) humans and chimpanzees share a relatively recent common ancestor. C) humans evolved from chimpanzees. D) humans and chimpanzees are not closely related. E) chimpanzees evolved from humans.

B

From his observations of organisms in the Galapagos islands, Darwin reasoned that _____. A) all island species should be similar to each other B) organisms had adapted to new environments, giving rise to new species C) the organisms in the Galapagos had been specially created to thrive in that environment D) the shape of a bird's beak does not affect its ability to survive and reproduce E) none of the above

B

In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population? A) 0.36 B) 0.80 C) 0.64 D) 0.75

B

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. In the United States, the parasite that causes malaria is not present, but African-Americans whose ancestors were from equatorial Africa are present. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa? A) disruptive selection; directional selection B) directional selection; stabilizing selection C) directional selection; disruptive selection D) disruptive selection; stabilizing selection E) stabilizing selection; disruptive selection

B

Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans. A) disease B) genetic drift C) natural selection D) mutation E) gene flow

B

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because A) humans purposefully raise MRSA in large fermenters in an attempt to make the bacteria ever-more resistant. B) humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin. C) S. aureus is cultivated by humans to replenish the soil with nutrients. D) humans are becoming resistant to bacteria by taking methicillin.

B

The role that humans play in artificial selection is to A) perform artificial insemination. B) choose which organisms breed, and which do not. C) train organisms to breed more successfully. D) determine who lives and who dies. E) create the genetic variants, which nature then selects.

B

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. With respect to the sickle-cell allele, what should be true of the β hemoglobin locus in U.S. populations of African-Americans whose ancestors were from equatorial Africa? 1. The average heterozygosity at this locus should be decreasing over time. 2. There is an increasing heterozygote advantage at this locus. 3. Diploidy is helping to preserve the sickle-cell allele at this locus. 4. Frequency-dependent selection is helping to preserve the sickle-cell allele at this locus. A) 1 only B) 1 and 3 C) 2 and 3 D) 1, 2, and 3 E) 1, 2, and 4

B

What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene? A) The expected genotype frequencies are 0.32, 0.64, and 0.04 for A1A1, A1A2 , and A2A2 , respectively. B) The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively. C) The expected genotype frequencies are 0.25, 0.5, and 0.25 for A1A1, A1A2 , and A2A2 , respectively. D) The expected genotype frequencies are 0.33, 0.33, and 0.33 for A1A1, A1A2 , and A2A2 , respectively.

B

What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals? A) The frequency of the A1 allele is 0.1. B) The frequency of the A1 allele is 0.3. C) The frequency of the A1 allele is 0.7. D) The frequency of the A1 allele is 0.5.

B

Which of the following are basic components of the Hardy-Weinberg model? A) Allele frequencies, phenotype frequencies B) Frequencies of two alleles in a gene pool before and after many random matings C) Allele frequencies in a subset of the population D) Allele frequencies, number of individuals in the population

B

You are studying three populations of birds. Population A has ten birds, of which one is brown (a recessive trait) and nine are red. Population B has 100 birds, of which ten are brown. Population C has 30 birds, and three of them are brown. In which population would it be least likely that an accident would significantly alter the frequency of the brown allele? A) population A B) population B C) population C D) They are all the same. E) It is impossible to tell from the information given.

B

**figure 10** A hypothetical population of 300 wolves has two alleles, FB and FW, for a locus that codes for fur color. The table below describes the phenotype of a wolf with each possible genotype, as well as the number of individuals in the population with each genotype. Which statements accurately describe the population of wolves? Select the four statements that are true. A) Based on the equation for Hardy-Weinberg equilibrium, the expected number of wolves with the FBFB genotype is 40. B) Based on the equation for Hardy-Weinberg equilibrium, the expected number of wolves with the FBFB genotype is 12. Based on the equation for Hardy-Weinberg equilibrium, the expected number of wolves with the FBFW genotype is 40. C) Based on the equation for Hardy-Weinberg equilibrium, the expected number of wolves with the FBFW genotype is 96. D) The population may be evolving because the actual number of individuals with each genotype differs from the expected number of individuals with each genotype. E) The population is not at Hardy-Weinberg equilibrium. F) The population is not evolving because it is at Hardy-Weinberg equilibrium.

B, C, D, E

**figure 3** The following question refers to the figure, which shows an outcrop of sedimentary rock whose strata are labeled A-D. If x indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum? A B C D

C

**figure 5** This animation illustrates _____ as it occurs during _____. A) random fertilization ... prophase I B) centrosome separation ... anaphase II C) crossing over ... prophase I D) cytokinesis ... telophase I E) karyokinesis ... prophase II

C

A challenge to traditional (pre-1860) ideas about species came from embryology, when it was discovered that _____. A) all animals develop similar embryonic gills B) the embryological development of many plants and animals is almost identical C) embryos of dissimilar organisms, such as sharks and humans, resemble each other D) the more advanced the animal, the more slowly it develops E) mutations have a far more dramatic effect on embryos than on adult organisms

C

A mutation occurs when _____. A) some individuals leave more offspring than other individuals B) individuals leave a population C) there is a change in the DNA sequence of a gene D) population sizes are small E) individuals enter a population

C

Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence? A) gene flow B) nonrandom mating C) genetic drift D) mutation E) natural selection

C

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true? A) Species X and Y are the result of artificial selection from an ancestral species Z. B) Species X and Y are not related to species Z. C) Species X and Y share a greater number of homologies with each other than either does with species Z. D) Species X and Y share a common ancestor that is still extant (in other words, not yet extinct). E) Species X, Y, and Z share a common ancestor, but nothing more can be claimed than this.

C

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception? A) Spontaneous mutations can result in the appearance of new traits. B) Only favorable adaptations have survival value. C) Characteristics acquired during an organism's life are generally not passed on through genes. D) If the giraffes did not have to compete with each other, longer necks would not have been passed on to the next generation. E) Disuse of an organ may lead to its eventual disappearance.

C

Every few years a giant axe chops off the head of every person who is over 6 feet tall. How will this affect the human population? A) It will increase in number since shorter people use fewer resources than taller people. B) Genetic drift will play less of a role in the evolution of humans. C) Alleles that promote "tallness" will decrease in frequency. D) The mutation rate will increase. E) Gene flow will increase.

C

If Darwin had been aware of genes, and of their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement? A) If an individual's somatic cell genes change during its lifetime, making it more fit, then it will be able to pass these genes on to its offspring. B) A single mutation in a single gene in a single gamete will, if perpetuated, produce a new species within just two generations. C) If natural selection can change one gene's frequency in a population over the course of generations then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones. D) If an individual acquires new genes by engulfing, or being infected by, another organism, then a new genetic species will be the result.

C

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

C

If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be A) 23%. B) 46%. C) 54%. D) There is not enough information to say.

C

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the frequency of individuals that are homozygous for this allele? A) 49.0 B) 0.49 C) 0.09 D) 9.0 E) 0.9

C

In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because A) the population is diploid. B) the population is doubling in number. C) heterozygotes can come about in two ways. D) heterozygotes have two alleles.

C

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes. If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet, about how many people will have attached earlobes when the planet's population reaches 10,000? A) 10,000 B) 400 C) 100 D) 800 E) 1,000

C

In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. The sickle-cell allele is pleiotropic (i.e., it affects more than one phenotypic trait). Specifically, this allele affects oxygen delivery to tissues and affects one's susceptibility to malaria. Under conditions of low atmospheric oxygen availability, individuals heterozygous for this allele can experience life-threatening sickle-cell "crises." Such individuals remain less susceptible to malaria. Thus, pleiotropic genes/alleles such as this can help explain why A) new advantageous alleles do not arise on demand. B) evolution is limited by historical constraints. C) adaptations are often compromises. D) chance events can affect the evolutionary history of populations.

C

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

C

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

C

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. Again, if this population were in equilibrium and if the sickle-cell allele is recessive, what proportion of the population should be susceptible to sickle-cell anemia under typical conditions? A) 0.32 B) 0.20 C) 0.04 D) 0.16 E) 0.80

C

Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies? A) Mutation B) Inbreeding C) Selection D) There is no evolutionary force that results in adaptive changes in allele frequencies.

C

Which of the following statements best describes theories? A) They are predictions of future events. B) They cannot be tested because the described events occurred only once. C) They are supported by, and make sense of, many observations. D) They are nearly the same things as hypotheses.

C

Which of these conditions should completely prevent the occurrence of evolution in a population over time? A) The population lives in a habitat where there are no competing species present. B) The population size is large. C) All phenotypic variation between individuals is due only to environmental factors. D) The environment is changing at a relatively slow rate.

C

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true? A) The frequency of the strong-beak alleles increased in each bird as the drought persisted. B) Each bird evolved a deeper, stronger beak as the drought persisted. C) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted. D) Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation.

C

**figure 2** The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (VZ) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. According to this tree, what percent of the species seem to be extant (in other words, not extinct)? A) 25% B) 33% C) 50% D) 66% E) 75%

D

**figure 2** The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (VZ) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five common ancestors, labeled VZ, has given rise to the greatest number of species, both extant and extinct? A) V B) W C) Z D) Both X and Y can be considered to have given rise to the greatest number of extant and extinct species. E) Both W and Z can be considered to have given rise to the greatest number of extant and extinct species.

D

**figure 3** The following question refers to the figure, which shows an outcrop of sedimentary rock whose strata are labeled A-D. If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata? A) four strata B) three strata C) one stratum D) two strata

D

A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true? A) The amount of available food may have increased. B) The parental generation of squirrels developed better eyesight due to improved diet; the subsequent squirrel generation inherited better eyesight. C) The number of predators that prey upon squirrels may have decreased. D) A and C could be true. E) A, B, and C could be true.

D

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time? A) There has been a high rate of mutation of allele A to allele a. B) The population is undergoing genetic drift. C) There has been sexual selection favoring allele a. D) The two phenotypes are about equally adaptive under laboratory conditions. E) The genotype AA is lethal.

D

A trend toward the decrease in the size of plants on the slopes of mountains as altitudes increase is an example of A) a bottleneck. B) geographic variation. C) relative fitness. D) a cline. E) genetic drift.

D

Blue poppies native to China were grown at a plant-breeding center in California. The plants with the thickest leaves were most likely to survive and reproduce in the drier climate. After several generations, the percentage of thick-leaved plants had increased by 42%. This adaptation of the poppies to their new environment is due to _____. A) stabilizing selection B) disruptive selection C) genetic drift D) directional selection E) neutral variation

D

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship. A) 2 → 4 → 3 → 1 B) 4 → 2 → 3 → 1 C) 4 → 1 → 2 → 3 D) 2 → 4 → 1 → 3 E) 4 → 2 → 1 → 3

D

How many of these statements regarding populations are true? 1. Mature males and females of a population can interbreed with each other. 2. Populations are sometimes geographically isolated from other populations. 3. Biological species are made up of populations. 4. Members of a population tend to be genetically more similar to each other than to members of other populations. 5. Populations have genomes, but not gene pools. A) Only one of these statements is true. B) Two of these statements are true. C) Three of these statements are true. D) Four of these statements are true. E) All five of these statements are true.

D

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

D

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype? A) 0.32 B) 0.42 C) 0.20 D) 0.81 E) Genotype frequency cannot be determined from the information provided.

D

In the year 2500, five male space colonists and five female space colonists (all unrelated to each other) settle on an uninhabited Earthlike planet in the Andromeda galaxy. The colonists and their offspring randomly mate for generations. All ten of the original colonists had free earlobes, and two were heterozygous for that trait. The allele for free earlobes is dominant to the allele for attached earlobes. Which of these is closest to the allele frequency in the founding population? A) 0.8 a, 0.2 A B) 0.5 a, 0.5 A C) 0.4 a, 0.6 A D) 0.1 a, 0.9 A E) 0.2 a, 0.8 A

D

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

D

Natural selection is based on all of the following except A) individuals who survive longer tend to leave more offspring than those who die young. B) populations tend to produce more individuals than the environment can support. C) the best-adapted individuals tend to leave the most offspring. D) individuals adapt to their environments and, thereby, evolve. E) genetic variation exists within populations.

D

The ease with which humans travel across the globe is likely to increase _____. A) mutation B) genetic drift C) natural selection D) gene flow E) all of these

D

The wing of a bat is homologous to the _____ of a whale. A) tail B) baleen C) rib cage D) flipper E) blowhole

D

Use the following information to answer the following question. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. Although selection is clearly present, if the ideal equilibrium of alleles existed, what should be the proportion of heterozygous individuals in populations that live here? A) 0.80 B) 0.20 C) 0.04 D) 0.32 E) 0.16

D

Which of the following is a true statement concerning genetic variation? A) It tends to be reduced by the processes involved when diploid organisms produce gametes. B) It arises in response to changes in the environment. C) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity. D) It must be present in a population before evolution can occur in the population. E) It is created by the direct action of natural selection.

D

Which of the following is not an observation or inference on which natural selection is based? A) Species produce more offspring than the environment can support. B) There is heritable variation among individuals. C) Only a fraction of an individual's offspring may survive. D) Poorly adapted individuals never produce offspring. E) Individuals whose characteristics are best suited to the environment generally leave more offspring than those whose characteristics are less well suited.

D

Which of the following statements is not a part of the Hardy-Weinberg principle? A) If allele frequencies in a population are given by p and q, then genotype frequencies will be given by p 2, 2pq, and q 2 for generation after generation. B) Even if allele A1 is dominant to allele A2 , it does not increase in frequency. C) When alleles are transmitted according to the rules of Mendelian inheritance, their frequencies do not change over time. D) The genotype frequencies in the offspring generation must add up to two.

D

Which of these individuals is a homozygous genotype? A) Aa B) AG C) Gg D) AA E) aG

D

You are maintaining a small population of fruit flies in the laboratory by transferring the flies to a new culture bottle after each generation. After several generations, you notice that the viability of the flies has decreased greatly. Recognizing that small population size is likely to be linked to decreased viability, the best way to reverse this trend is to A) reduce the number of flies that you transfer at each generation. B) transfer only the largest flies. C) shock the flies with a brief treatment of heat or cold to make them more hardy. D) cross your flies with flies from another lab. E) change the temperature at which you rear the flies.

D

**figure 6** Blue light is a portion of the visible spectrum that penetrates deep into bodies of water. Ultraviolet (UV) light, though, can penetrate even deeper. A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light, and another allele for a photopigment that is sensitive to blue light. Which of the following graphs best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best? A) D B) C C) A D) B

D. B

**figure 2** The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (VZ) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. Which of the five common ancestors, labeled VZ, has been most successful in terms of the percent of its derived species that are extant? A) V B) W C) X D) Y E) Z

E

**figure 2** The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (VZ) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. How many separate species, both extant and extinct, are depicted in this tree? A) two B) three C) four D) five E) six

E

A group of small fish live in a lake with a uniformly light-brown sandy bottom. Most of the fish are light brown, but about 10% are mottled. This fish species is often prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction of what will happen to this fish population? A) There is no way to predict the result. B) The ratios will not change. C) As the mottled fish are eaten, more will be produced to fill the gap. D) In two generations, all the fish will be mottled. E) The proportion of mottled fish will increase over time.

E

All the genes in a population are that population's _____. A) phenotype B) Hardy-Weinberg C) fitness D) genotype E) gene pool

E

Crossing over, resulting in an increase in genetic variation, occurs between _____. A) nonsister chromatids of nonhomologous chromosomes B) sister chromatids of homologous chromosomes C) sister chromatids of nonhomologous chromosomes D) sex cells and somatic cells E) nonsister chromatids of homologous chromosomes

E

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run? A) The frequency of DDT application should have been higher. B) Larger doses of DDT should have been applied. C) DDT application should have been continual. D) All habitats should have received applications of DDT at about the same time. E) None of the individual insects should have possessed genomes that made them resistant to DDT.

E

Evolution A) requires that populations become better suited to their environments. B) must happen whenever a population is not well-adapted to its environment. C) requires the operation of natural selection. D) must happen, due to organisms' innate desire to survive. E) can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met.

E

Hardy-Weinberg equilibrium must occur in populations wherein A) natural selection is not operating. B) an allele remains fixed. C) no genetic variation exists. D) All three of the responses above are correct. E) Only two of the responses above are correct.

E

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

E

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations? A) selection for algae-eaters that are faster swimmers B) selection for drab coloration of the algae-eaters C) selection for algae-eaters that become sexually mature at smaller overall body sizes D) selection for larger female algae-eaters, bearing broods composed of more, and larger, young E) selection for nocturnal algae-eaters (active only at night)

E

In evolutionary terms, an organism's fitness is measured by its _____. A) mutation rate B) health C) stability in the face of environmental change D) genetic variability E) contribution to the gene pool of the next generation

E

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

E

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data? A) Genes mutate faster in whales than in humans or bats. B) Forelimb evolution was adaptive in people and bats, but not in whales. C) Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms. D) Whales are not properly classified as mammals. E) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.

E

Varieties of Staphylococcus aureus that are resistant to the drug methicillin _____. A) developed in response to the use of methicillin B) already existed in the population before methicillin was developed C) always have an advantage in every environment D) were strongly selected for as methicillin became widely used to treat bacterial infections E) The second and fourth answers are correct.

E

What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population? A) nucleotide variability B) gene flow C) mutation D) bottleneck effect E) founder effect

E

Which of the following must exist in a population before natural selection can act upon that population? A) variation among individuals in reproductive success B) sexual reproduction C) genetic variation among individuals D) Three of the responses are correct. E) Two of the responses are correct.

E

Which of the following observations led to Darwin's major inferences? A) Members of a population vary in their heritable traits. B) Body parts that are not used deteriorate over time. C) Organisms only go extinct when catastrophes occur. D) Although organisms can produce huge numbers of offspring, many of these offspring do not survive. E) The first and fourth answers are correct.

E

Which statement about variation is true? A) All nucleotide variability results in neutral variation. B) All phenotypic variation is the result of genotypic variation. C) All geographic variation results from the existence of clines. D) All genetic variation produces phenotypic variation. E) None of the above

E

You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population? A) 0.07 B) 0.09 C) 0.08 D) 0.70 E) Allele frequency cannot be determined from this information.

E

Charles Darwin described evolution as "descent with modification," meaning that species change through time. A great deal of evidence indicates that life has evolved over time and continues to evolve. Natural selection is the primary mechanism by which evolution takes place. Part A - Scientific evidence supporting evolution Scientific evidence documents the pattern of evolution. The evidence exists in a variety of categories, including direct observation of evolutionary change, the fossil record, homology, and biogeography. Sort the following examples into the correct categories. Categories: I. Direct observation of evolutionary change II. Fossil record III. Homology IV. Biogeography Examples: i. Discovery of shells of extinct species ii. Similarities in mammalian forelimbs iii. Development of drug resistance in bacteria iv. Discovery of transitional forms of horses v. Similarity of endemic island species to nearby mainland species vi. Same genetic code in fireflies and tobacco plants vii. Vestigial pelvis in right whales viii. The high concentration of marsupial species in Australia Part B The island fox, Urocyon littoralis, is endemic to the Channel Islands, which are located off the coast of southern California. Six of the eight Channel Islands support fox populations, and each of these islands is home to a distinct subspecies, as shown in the table below. **figure 4** The island fox shares a common ancestor with the gray fox, Urocyon cinereoargenteus, which is found on the mainland. Both species have similar coloration and a diploid chromosome number of 66. One structural difference between the two species is the reduced size of the island fox, a feature known as dwarfism. The various island subspecies also differ from each other in size, number of tail vertebrae, and other characteristics. The phylogenetic tree below shows the evolutionary relationships between the island fox subspecies and the gray fox. Drag the labels to their appropriate locations on the tree. **figure 4 i. ancestor of santa catalina and san clemente foxes ii. ancestor of southern channel island foxes iii. ancestor of gray foxes and island foxes iv. ancestor of island foxes v. most closely related vi. ancestor of santa rosa and and san miguel foxes vii. ancestor of northern channel island foxes viii. dwarfism

Part A I. iii II. i,iv III. vi, ii, vii IV. viii, v Part B A. iii B. vi C. viii D. vii E. v F. ii G. iv H. i

True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating. True False

True