BSC 114 Exam 4 Stephenson

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You sample a population of butterflies and find that 42% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population? A) 0.09 B) 0.30 C) 0.49 D) 0.70 E) Allele frequency cannot be determined from this information.

A) 0.09

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) 0.1 a, 0.9 A B) 0.2 a, 0.8 A C) 0.5 a, 0.5 A D) 0.8 a, 0.2 A E) 0.4 a, 0.6 A

A) 0.1 a, 0.9 A

A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 and A2? A) 0.7 B) 0.49 C) 0.21 D) 0.42 E) 0.09

A) 0.7

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) 100 B) 400 C) 800 D) 1,000 E) 10,000

A) 100

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 1 3 B) 4 2 1 3 C) 4 1 2 3 D) 4 2 3 1 E) 2 4 3 1

A) 2 4 1 3

Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA. A) 2, 1, 4 B) 1, 3, 2, 4 C) 3, 4, 1, 2 D) 3, 4, 2 E) 2, 3, 4

A) 2, 1, 4

Which of the following would be a position held by an adherent of the punctuated equilibrium theory? A) A new species forms most of its unique features as it comes into existence and then changes little for the duration of its existence. B) One should expect to find many transitional fossils left by organisms in the process of forming new species. C) Given enough time, most existing species will gradually evolve into new species. D) Natural selection is unimportant as a mechanism of evolution.

A) A new species forms most of its unique features as it comes into existence and then changes little for the duration of its existence.

Which of these makes determining the evolutionary relatedness of different species based on the amino acid sequence of homologous proteins generally less accurate than determinations of relatedness based on the nucleotide sequences of homologous genes? A) Silent mutations B) Gene duplications C) Translocation events that change gene sequences D) Crossing-over E) Independent assortment

A) Silent mutations

Which was developed by a British researcher and causes DNA sequences to be transferred to a membrane and identified with a probe? A) Southern blotting B) Northern blotting C) Western blotting D) Eastern blotting E) RT-PCR

A) Southern blotting

Which of the following statements is an inference of natural selection? A) Subsequent generations of a population should have greater proportions of individuals that possess traits better suited for success in unchanging environments. B) An individual organism undergoes evolution over the course of its lifetime. C) Habitats do not generally have unlimited resources. D) Natural populations tend to reproduce to their full biological potential. E) Some of the variation that exists among individuals in a population is genetic.

A) Subsequent generations of a population should have greater proportions of individuals that possess traits better suited for success in unchanging environments.

Homeotic genes contain a homeobox sequence that is highly conserved among very diverse species. The homeobox is the code for that domain of a protein that binds to DNA in a regulatory developmental process. Which of the following would you then expect? A) That homeotic genes are selectively expressed over developmental time. B) That a homeobox containing gene has to be a developmental regulator. C) That homeoboxes cannot be expressed in non-homeotic genes. D) That all organisms must have homeotic genes. E) That all organisms must have homeobox containing genes.

A) That homeotic genes are selectively expressed over developmental time.

How does a bacterial cell protect its own DNA from restriction enzymes? A) adding methyl groups to adenines and cytosines B) using DNA ligase to seal the bacterial DNA into a closed circle C) adding histones to protect the double-stranded DNA D) forming sticky ends of bacterial DNA to prevent the enzyme from attaching E) reinforcing the bacterial DNA structure with covalent phosphodiester bonds

A) adding methyl groups to adenines and cytosines

Which of the following modifications is least likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis? A) altering the nucleotide sequence of the DNA fragment B) methylating the cytosine bases within the DNA fragment C) increasing the length of the DNA fragment D) decreasing the length of the DNA fragment E) neutralizing the negative charges within the DNA fragment

A) altering the nucleotide sequence of the DNA fragment

Cell differentiation always involves the A) production of tissue-specific proteins, such as muscle actin. B) movement of cells. C) transcription of the myoD gene. D) selective loss of certain genes from the genome. E) cell s sensitivity to environmental cues such as light or heat.

A) production of tissue-specific proteins, such as muscle actin.

Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis? A) rabies B) herpesvirus C) smallpox D) HIV E) hepatitis virus

A) rabies

The DNA fragments making up a genomic library are generally contained in A) recombinant plasmids of bacteria. B) recombinant viral RNA. C) individual wells. D) DNA-RNA hybrids E) radioactive eukaryotic cells

A) recombinant plasmids of bacteria.

A researcher has used in vitro mutagenesis to mutate a cloned gene and then has reinserted this into a cell. In order to have the mutated sequence disable the function of the gene, what must then occur? A) recombination resulting in replacement of the wild type with the mutated gene B) use of a microarray to verify continued expression of the original gene C) replication of the cloned gene using a bacterial plasmid D) transcription of the cloned gene using a BAC E) attachment of the mutated gene to an existing mRNA to be translated

A) recombination resulting in replacement of the wild type with the mutated gene

The difference between geographic isolation and habitat differentiation is the A) relative locations of two populations as speciation occurs. B) speed (tempo) at which two populations undergo speciation. C) amount of genetic variation that occurs among two gene pools as speciation occurs. D) identity of the phylogenetic kingdom or domain in which these phenomena occur. E) the ploidy of the two populations as speciation occurs.

A) relative locations of two populations as speciation occurs.

The cancer-causing forms of the Ras protein are involved in which of the following processes? A) relaying a signal from a growth factor receptor B) DNA replication C) DNA repair D) cell-cell adhesion E) cell division

A) relaying a signal from a growth factor receptor

RFLP analysis can be used to distinguish between alleles based on differences in which of the following? A) restriction enzyme recognition sites between the alleles B) the amount of DNA amplified from the alleles during PCR C) the ability of the alleles to be replicated in bacterial cells D) the proteins expressed from the alleles E) the ability of nucleic acid probes to hybridize to the alleles

A) restriction enzyme recognition sites between the alleles

Which of the following cuts DNA molecules at specific locations? A) restriction enzymes B) gene cloning C) DNA ligase D) gel electrophoresis E) reverse transcriptase

A) restriction enzymes

What is the name given to viruses that are single-stranded RNA that acts as a template for DNA synthesis? A) retroviruses B) proviruses C) viroids D) bacteriophages E) lytic phages

A) retroviruses

Adult male humans generally have deeper voices than do adult female humans, as the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females, and increasing larynx size in adult males, then A) sexual dimorphism was developing over time in these species. B) intrasexual selection seems to have occurred. C) the good genes hypothesis was refuted by these data. D) stabilizing selection was occurring in these species concerning larynx size. E) selection was acting more directly upon genotype than upon phenotype.

A) sexual dimorphism was developing over time in these species.

The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is A) sexual selection. B) habitat differentiation. C) polyploidy. D) pollution. E) introduction of a new predator.

A) sexual selection.

Which of the following is established prior to fertilization in Drosophila eggs? A) the anterior-posterior and dorsal-ventral axes B) the position of the future segments C) the position of the future wings, legs, and antennae D) A and B only E) A, B, and C

A) the anterior-posterior and dorsal-ventral axes

The product of the bicoid gene in Drosophila provides essential information about A) the anterior-posterior axis. B) the dorsal-ventral axis. C) the left-right axis. D) segmentation. E) lethal genes.

A) the anterior-posterior axis.

The Darwinian fitness of an individual is measured most directly by A) the number of its offspring that survive to reproduce. B) the number of good genes it possesses. C) the number of mates it attracts. D) its physical strength. E) how long it lives.

A) the number of its offspring that survive to reproduce.

Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate? A) the postzygotic barrier called hybrid inviability B) the postzygotic barrier called hybrid breakdown C) the prezygotic barrier called hybrid sterility D) gametic isolation E) adaptation

A) the postzygotic barrier called hybrid inviability

The host range of a virus is determined by A) the proteins on its surface and that of the host. B) whether its nucleic acid is DNA or RNA. C) the proteins in the host s cytoplasm. D) the enzymes produced by the virus before it infects the cell. E) the enzymes carried by the virus.

A) the proteins on its surface and that of the host.

One of the characteristics of retrotransposons is that A) they code for an enzyme that synthesizes DNA using an RNA template. B) they are found only in animal cells. C) they generally move by a cut-and-paste mechanism. D) they contribute a significant portion of the genetic variability seen within a population of gametes. E) their amplification is dependent on a retrovirus.

A) they code for an enzyme that synthesizes DNA using an RNA template.

DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. What is the purpose of transferring the DNA from a gel to a nitrocellulose paper? A) to attach the DNA fragments to a permanent substrate B) to separate the two complementary DNA strands C) to transfer only the DNA that is of interest D) to prepare the DNA for digestion with restriction enzymes E) to separate out the PCRs

A) to attach the DNA fragments to a permanent substrate

The functioning of enhancers is an example of A) transcriptional control of gene expression. B) a post-transcriptional mechanism for editing mRNA. C) the stimulation of translation by initiation factors. D) post-translational control that activates certain proteins. E) a eukaryotic equivalent of prokaryotic promoter functioning.

A) transcriptional control of gene expression.

The difference between vertical and horizontal transmission of plant viruses is that A) vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant. B) vertical transmission is the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. C) vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. D) vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type. E) vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of viruses among plants of the same species.

A) vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant.

What does the operon model attempt to explain? A. The coordinated control of gene expression in bacteria B. bacterial resistance to antibiotics C. How genes move between homologous regions of DNA D. the mechanism of viral attachment to a host cell E. horizontal transmission of plant viruses

A. The coordinated control of gene expression in bacteria

In both eukaryotes and prokaryotes, gene expression is primarily regulated at the level of A) transcription. B) translation. C) mRNA stability. D) mRNA splicing. E) protein stability.

A. Transcription

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals with Aa genotype? A) 0.20 B) 0.32 C) 0.42 D) 0.80 E) Genotype frequency cannot be determined from the information provided.

B) 0.32

Some members of a photosynthetic plant species are genetically resistant to an herbicide, while other members of the same species are not resistant to the herbicide. Which combination of events should cause the most effective replacement of the non-herbicide-resistant strain of plants by the resistant strain? 1. The presence of the herbicide in the environment 2. The absence of the herbicide from the environment 3. The maintenance of the proper conditions for one generation 4. The maintenance of the proper conditions for many generations A) 1 and 3 B) 1 and 4 C) 2 and 3 D) 2 and 4

B) 1 and 4

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.4. What is the percentage of the population that is homozygous for this allele? A) 4 B) 16 C) 32 D) 36 E) 40

B) 16

Rank the following from most general to most specific: 1. gametic isolation 2. reproductive isolating mechanism 3. pollen-stigma incompatibility 4. prezygotic isolating mechanism A) 2, 3, 1, 4 B) 2, 4, 1, 3 C) 4, 1, 2, 3 D) 4, 2, 1, 3 E) 2, 1, 4, 3

B) 2, 4, 1, 3

Rank the following 1-base point mutations (from most likely to least likely) with respect to their likelihood of affecting the structure of the corresponding polypeptide: 1. insertion mutation deep within an intron 2. substitution mutation at the 3rd position of an exonic codon 3. substitution mutation at the 2nd position of an exonic codon 4. deletion mutation within the first exon of the gene A) 1, 2, 3, 4 B) 4, 3, 2, 1 C) 2, 1, 4, 3 D) 3, 1, 4, 2 E) 2, 3, 1, 4

B) 4, 3, 2, 1

Why is it unwise to try to relate an organism s complexity with its size or number of cells? A) A very large organism may be composed of very few cells or very few cell types. B) A single-celled organism, such as a bacterium or a protist, still has to conduct all the complex life functions of a large multicellular organism. C) A single-celled organism that is also eukaryotic, such as a yeast, still reproduces mitotically. D) A simple organism can have a much larger genome. E) A complex organism can have a very small and simple genome.

B) A single-celled organism, such as a bacterium or a protist, still has to conduct all the complex life functions of a large multicellular organism.

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

B) All organisms use essentially the same genetic code.

Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell? A) The repressor protein attaches to the regulator. B) Allolactose binds to the repressor protein. C) Allolactose binds to the regulator gene. D) The repressor protein and allolactose bind to RNA polymerase. E) RNA polymerase attaches to the regulator.

B) Allolactose binds to the repressor protein.

Monkeys of South and Central America have prehensile tails, meaning that their tails can be used to grasp objects. The tails of African and Asian monkeys are not prehensile. Which discipline is most likely to provide an evolutionary explanation for how this difference in tails came about? A) Aerodynamics B) Biogeography C) Physiology D) Biochemistry E) Botany

B) Biogeography

Darwin s mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earth s ancient age? A) Georges Cuvier B) Charles Lyell C) Alfred Wallace D) Thomas Malthus E) John Henslow

B) Charles Lyell

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation? A) Use of adult stem cells is likely to produce more cell types than use of embryonic stem cells. B) Cloning to produce embryonic stem cells may lead to great medical benefits for many. C) Cloning to produce stem cells relies on a different initial procedure than reproductive cloning. D) A clone that lives until the blastocyst stage does not yet have human DNA. E) No embryos would be destroyed in the process of therapeutic cloning.

B) Cloning to produce embryonic stem cells may lead to great medical benefits for many.

Who would have proposed that the boundaries between each stratum mark the occurrence of different localized floods? A) Lyell B) Cuvier C) Hutton D) Darwin E) Lamarck

B) Cuvier

Which pair would have been likely to agree that strata such as those depicted here were deposited gradually over long periods of time by subtle mechanisms that are still at work? A) Cuvier and Aristotle B) Cuvier and Lamarck C) Lyell and Linnaeus D) Aristotle and Hutton E) Hutton and Lyell

B) Cuvier and Lamarck

Which of the following tools of recombinant DNA technology is incorrectly paired with its use? A) restriction enzyme-production of RFLPs B) DNA ligase-enzyme that cuts DNA, creating the sticky ends of restriction fragments C) DNA polymerase-used in a polymerase chain reaction to amplify sections of DNA D) reverse transcriptase-production of cDNA from mRNA E) electrophoresis-separation of DNA fragments

B) DNA ligase-enzyme that cuts DNA, creating the sticky ends of restriction fragments

Barbara McClintock, famous for discovering that genes could move within genomes, had her meticulous work ignored for nearly 4 decades, but eventually won the Nobel Prize. Why was her work so distrusted? A) The work of women scientists was still not allowed to be published. B) Geneticists did not want to lose their cherished notions of DNA stability. C) There were too many alternative explanations for transposition. D) She allowed no one else to duplicate her work. E) She worked only with maize, which was considered merely a plant.

B) Geneticists did not want to lose their cherished notions of DNA stability.

Races of humans are unlikely to evolve extensive differences in the future for which of the following reasons? I. The environment is unlikely to change. II. Human evolution is complete. III. The human races are incompletely isolated. A) I only B) III only C) I and II only D) II and III only E) I, II, and III

B) III only

Which of the following would not be true of cDNA produced using human brain tissue as the starting material? A) It could be amplified by the polymerase chain reaction. B) It could be used to create a complete genomic library. C) It is produced from mRNA using reverse transcriptase. D) It could be used as a probe to detect genes expressed in the brain. E) It lacks the introns of the human genes.

B) It could be used to create a complete genomic library.

What is the function of reverse transcriptase in retroviruses? A) It hydrolyzes the host cell s DNA. B) It uses viral RNA as a template for DNA synthesis. C) It converts host cell RNA into viral DNA. D) It translates viral RNA into proteins. E) It uses viral RNA as a template for making complementary RNA strands.

B) It uses viral RNA as a template for DNA synthesis.

Which of the following describes plant virus infections? A) They can be controlled by the use of antibiotics. B) They are spread throughout a plant by passing through the plasmodesmata. C) They have little effect on plant growth. D) They are seldom spread by insects. E) They can never be inherited from a parent.

B) They are spread throughout a plant by passing through the plasmodesmata.

Which of the following is true of embryonic stem cells but not of adult stem cells? A) They can differentiate into many cell types. B) They make up the majority of cells of the tissue from which they are derived. C) They can continue to replicate for an indefinite period. D) They can provide enormous amounts of information about the process of gene regulation. E) One aim of using them is to provide cells for repair of diseased tissue.

B) They make up the majority of cells of the tissue from which they are derived.

Which of the following represents a difference between viruses and viroids? A) Viruses infect many types of cells, whereas viroids infect only prokaryotic cells. B) Viruses have capsids composed of protein, whereas viroids have no capsids. C) Viruses contain introns; viroids have only exons. D) Viruses always have genomes composed of DNA, whereas viroids always have genomes composed of RNA. E) Viruses cannot pass through plasmodesmata; viroids can.

B) Viruses have capsids composed of protein, whereas viroids have no capsids.

RNA viruses require their own supply of certain enzymes because A) host cells rapidly destroy the viruses. B) host cells lack enzymes that can replicate the viral genome. C) these enzymes translate viral mRNA into proteins. D) these enzymes penetrate host cell membranes. E) these enzymes cannot be made in host cells.

B) host cells lack enzymes that can replicate the viral genome.

What does the field often called evo-devo study? A) whether or not development is an evolutionary process B) how developmental processes have evolved C) whether or not all animals have developmental regulation D) whether the pattern of human development evolved early or late E) whether or not there are specific genes controlling development

B) how developmental processes have evolved

Evolutionary trees such as this are properly understood by scientists to be A) theories. B) hypotheses. C) laws. D) dogmas. E) facts.

B) hypotheses.

Genetically engineered plants A) are more difficult to engineer than animals. B) include a transgenic rice plant that can help prevent vitamin A deficiency. C) are being rapidly developed, but traditional plant breeding programs are still the only method used to develop new plants. D) are able to fix nitrogen themselves. E) are banned throughout the world

B) include a transgenic rice plant that can help prevent vitamin A deficiency.

Antiviral drugs that have become useful are usually associated with which of the following properties? A) ability to remove all viruses from the infected host B) interference with the viral reproduction C) prevention of the host from becoming infected D) removal of viral proteins E) removal of viral mRNAs

B) interference with the viral reproduction

The MyoD protein A) can promote muscle development in all cell types. B) is a transcription factor that binds to and activates the transcription of muscle-related genes. C) was used by researchers to convert differentiated muscle cells into liver cells. D) magnifies the effects of other muscle proteins. E) is a target for other proteins that bind to it.

B) is a transcription factor that binds to and activates the transcription of muscle-related genes.

For mapping studies of genomes, most of which were far along before 2000, the 3 -stage method was often used. Which is the usual order in which the stages were performed, assuming some overlap of the three? A) genetic map, sequencing of fragments, physical map B) linkage map, physical map, sequencing of fragments C) sequencing of entire genome, physical map, genetic map D) cytogenetic linkage, sequencing, physical map E) physical map, linkage map, sequencing

B) linkage map, physical map, sequencing of fragments

What was the species concept most used by Linnaeus? A) biological B) morphological C) ecological D) phylogenetic

B) morphological

A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). The researcher would like to compare a specific region of the DNA from the sample with DNA from living birds. Which of the following would be most useful for increasing the amount of dodo DNA available for testing? A) RFLP analysis B) polymerase chain reaction (PCR) C) electroporation D) gel electrophoresis E) Southern blotting

B) polymerase chain reaction (PCR)

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island s lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. If the low number of hybrid flies in the hybrid zone, relative to the number of D. santomea flies there, is due to the fact that hybrids are poorly adapted to conditions in the hybrid zone, and if fewer hybrid flies are produced with the passage of time, this is most likely to lead to A) fusion. B) reinforcement. C) stability. D) further speciation events.

B) reinforcement.

Which of the following experimental procedures is most likely to hasten mRNA degradation in a eukaryotic cell? A) enzymatic shortening of the poly(A) tail B) removal of the 5 cap C) methylation of C nucleotides D) memethylation of histones E) removal of one or more exons

B) removal of the 5 cap

Gap genes and pair-rule genes fall into this category: A) homeotic genes B) segmentation genes C) egg-polarity genes D) morphogens E) inducers

B) segmentation genes

These genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo: A) homeotic genes B) segmentation genes C) egg-polarity genes D) morphogens E) inducers

B) segmentation genes

Dideoxyribonucleotide chain-termination is a method of A) cloning DNA. B) sequencing DNA. C) digesting DNA. D) synthesizing DNA. E) separating DNA fragments.

B) sequencing DNA.

Heterozygote advantage should be most closely linked to which of the following? A) sexual selection B) stabilizing selection C) random selection D) directional selection E) disruptive selection

B) stabilizing selection

Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating A) the bottleneck effect. B) stabilizing selection. C) frequency-dependent selection. D) neutral variation. E) disruptive selection.

B) stabilizing selection.

Transcription of the structural genes in an inducible operon A) occurs continuously in the cell. B) starts when the pathway s substrate is present. C) starts when the pathway s product is present. D) stops when the pathway s product is present. E) does not result in the production of enzymes.

B) starts when the pathway s substrate is present.

Beetle pollinators of a particular plant are attracted to its flowers bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it? A) allopatric speciation, ecological isolation B) sympatric speciation, habitat differentiation C) allopatric speciation, behavioral isolation D) sympatric speciation, sexual selection E) sympatric speciation, allopolyploidy

B) sympatric speciation, habitat differentiation

The origin of a new plant species by hybridization, coupled with accidents during nuclear division, is an example of A) allopatric speciation. B) sympatric speciation. C) autopolyploidy. D) habitat selection.

B) sympatric speciation.

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier s attempt to explain the existence of A) evolution. B) the fossil record. C) uniformitarianism. D) the origin of new species. E) natural selection.

B) the fossil record.

What is considered to be the first evidence of differentiation in the cells of an embryo? A) cell division B) the occurrence of mRNAs for the production of tissue-specific proteins C) determination D) changes in the size and shape of the cell E) changes resulting from induction

B) the occurrence of mRNAs for the production of tissue-specific proteins

Within a cell, the amount of protein made using a given mRNA molecule depends partly on A) the degree of DNA methylation. B) the rate at which the mRNA is degraded. C) the presence of certain transcription factors. D) the number of introns present in the mRNA. E) the types of ribosomes present in the cytoplasm.

B) the rate at which the mRNA is degraded.

No two people are genetically identical, except for identical twins. The chief cause of genetic variation among human individuals is A) new mutations that occurred in the preceding generation. B) the reshuffling of alleles in sexual reproduction. C) genetic drift due to the small size of the population. D) geographic variation within the population. E) environmental effects.

B) the reshuffling of alleles in sexual reproduction.

What is proteomics? A) the linkage of each gene to a particular protein B) the study of the full protein set encoded by a genome C) the totality of the functional possibilities of a single protein D) the study of how amino acids are ordered in a protein E) the study of how a single gene activates many proteins

B) the study of the full protein set encoded by a genome

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

B) they should share fewer homologous structures than two more closely related organisms.

RNAi methodology uses double-stranded pieces of RNA to trigger a breakdown or blocking of mRNA. For which of the following might it more possibly be useful? A) to raise the rate of production of a needed digestive enzyme B) to decrease the production from a harmful gain-of-function mutated gene C) to destroy an unwanted allele in a homozygous individual D) to form a knockout organism that will not pass the deleted sequence to its progeny E) to raise the concentration of a desired protein

B) to decrease the production from a harmful gain-of-function mutated gene

When this is taken up by the cell, it binds to the repressor so that the repressor no longer binds to the operator: A) operon B) inducer C) promoter D) repressor E) corepressor

B. inducer

C) 0.50

In a hypothetical population of 1,000 people, tests of blood-type genes show that 160 have the genotype AA, 480 have the genotype AB, and 360 have the genotype BB. If there are 4,000 children born to this generation, how many would be expected to have AB blood under the conditions of Hardy-Weinberg equilibrium? A) 100 B) 960 C) 1,920 D) 2,000 E) 2,400

C) 1,920

Which of the following seems to be the known upper and lower size limits of genomes? A) 1—2900 Mb (million base pairs) B) 1,500—40,000 Mb C) 1—580,000 Mb D) 100—120,000 Mb E) 100—200,000 Mb

C) 1—580,000 Mb

Arrange the following from most general (i.e., most inclusive) to most specific (i.e., least inclusive): 1. Natural selection 2. Microevolution 3. Intrasexual selection 4. Evolution 5. Sexual selection A) 4, 1, 2, 3, 5 B) 4, 2, 1, 3, 5 C) 4, 2, 1, 5, 3 D) 1, 4, 2, 5, 3 E) 1, 2, 4, 5, 3

C) 4, 2, 1, 5, 3

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) 92% E) There is not enough information to say.

C) 54%

How does a genomic library differ from a cDNA library? A) A genomic library contains only noncoding sequences, whereas a cDNA library contains only coding sequences. B) A genomic library varies, dependent on the cell type used to make it, whereas the content of a cDNA library does not. C) A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase. D) The genomic library can be replicated but not transcribed. E) The genomic library contains only the genes that can be expressed in the cell.

C) A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase.

Which of these naturalists synthesized a concept of natural selection independently of Darwin? A) Charles Lyell B) Gregor Mendel C) Alfred Wallace D) John Henslow E) Thomas Malthus

C) Alfred Wallace

Alu elements account for about 10% of the human genome. What does this mean? A) Alu elements cannot be transcribed into RNA. B) Alu elements evolved in very ancient times, before mammalian radiation. C) Alu elements represent the result of transposition. D) No Alu elements are found within individual genes. E) Alu elements are cDNA and therefore related to retrotransposons.

C) Alu elements represent the result of transposition.

In a series of experiments, the enzyme Dicer has been inactivated in cells from various vertebrates, and the centromere is abnormally formed from chromatin. Which of the following is most likely to occur? A) The usual mRNAs transcribed from centromeric DNA will be missing from the cells. B) Tetrads will no longer be able to form during meiosis I. C) Centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture. D) The cells will no longer be able to resist bacterial contamination. E) The DNA of the centromeres will no longer be able to replicate.

C) Centromeres will be euchromatic rather than heterochromatic and the cells will soon die in culture

Which of the following seals the sticky ends of restriction fragments to make recombinant DNA? A) restriction enzymes B) gene cloning C) DNA ligase D) gel electrophoresis E) reverse transcriptase

C) DNA ligase

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true? A) Each bird evolved a deeper, stronger beak as the drought persisted. B) Each bird developed 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. E) The frequency of the strong-beak alleles increased in each bird as the drought persisted.

C) Each bird s survival was strongly influenced by the depth and strength of its beak as the drought persisted.

Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than prokaryotes because of which of the following? A) Eukaryotic mRNAs get 5 caps and 3 tails. B) Prokaryotic genes are expressed as mRNA, which is more stable in the cell. C) Eukaryotic exons may be spliced in alternative patterns. D) Prokaryotes use ribosomes of different structure and size. E) Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.

C) Eukaryotic exons may be spliced in alternative patterns.

Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme? A) AAGG TTCC B) AGTC TCAG C) GGCC CCGG D) ACCA TGGT E) AAAA TTTT

C) GGCC CCGG

Each of the following has a better chance of influencing gene frequencies in small populations than in large populations, but which one most consistently requires a small population as a precondition for its occurrence? A) Mutation B) Non-random mating C) Genetic drift D) Natural selection E) Gene flow

C) Genetic drift

Which of the following is a representation of gene density? A) Humans have 2,900 Mb per genome. B) C. elegans has ~20,000 genes. C) Humans have ~25,000 genes in 2,900 Mb. D) Humans have 27,000 bp in introns. E) Fritillaria has a genome 40 times the size of a human.

C) Humans have ~25,000 genes in 2,900 Mb.

Which of the following statements about species, as defined by the biological species concept, is (are) correct? I.Biological species are defined by reproductive isolation. II.Biological species are the model used for grouping extinct forms of life. III. The biological species is the largest unit of population in which successful reproduction is possible. A) I only B) II only C) I and III D) II and III E) I, II, and III

C) I and III

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA. A) I, II, IV, III, V B) II, III, V, IV, I C) III, II, IV, V, I D) III, IV, V, I, II E) IV, V, I, II, III

C) III, II, IV, V, I

Adult male humans generally have deeper voices than do adult female humans, as the direct result of higher levels of testosterone causing growth of the larynx. Which addition to the information in the paragraph above would make more than one of the answers listed in the previous question correct? A) If larynx size was also affected by the amount the larynx was used (i.e., the amount of vocalization). B) If males prefer to mate with females possessing higher voices. C) If females killed female offspring whose voices were too deep. D) If the trend described above was seen in the fossil record of only one species of ape.

C) If females killed female offspring whose voices were too deep.

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

C) It must be present in a population before natural selection can act upon the population.

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko s attempts in this regard were most in agreement with the ideas of A) Cuvier. B) Hutton. C) Lamarck. D) Darwin. E) Plato.

C) Lamarck.

In order to determine the probable function of a particular sequence of DNA in humans, what might be the most reasonable approach? A) Prepare a knockout mouse without a copy of this sequence and examine the mouse phenotype. B) Genetically engineer a mouse with a copy of this sequence and examine its phenotype. C) Look for a reasonably identical sequence in another species, prepare a knockout of this sequence in that species and look for the consequences. D) Prepare a genetically engineered bacterial culture with the sequence inserted and assess which new protein is synthesized. E) Mate two individuals heterozygous for the normal and mutated sequences.

C) Look for a reasonably identical sequence in another species, prepare a knockout of this sequence in that species and look for the consequences.

A principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that A) prokaryotes use a different genetic code from that of eukaryotes. B) bacteria translate polycistronic messages only. C) bacteria cannot remove eukaryotic introns. D) bacterial RNA polymerase cannot make RNA complementary to mammalian DNA. E) bacterial DNA is not found in a membrane-bounded nucleus and is therefore incompatible with mammalian DNA.

C) bacteria cannot remove eukaryotic introns.

To cause a human pandemic, the H5N1 avian flu virus would have to A) spread to primates such as chimpanzees. B) develop into a virus with a different host range. C) become capable of human-to-human transmission. D) arise independently in chickens in North and South America. E) become much more pathogenic.

C) become capable of human-to-human transmission.

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian islands have different elaborate courtship rituals that involve fighting other males and stylized movements that attract females. What type of reproductive isolation does this represent? A) habitat isolation B) temporal isolation C) behavioral isolation D) gametic isolation E) postzygotic barriers

C) behavioral isolation

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools? A) phylogenetic B) ecological C) biological D) morphological

C) biological

Tumor suppressor genes A) are frequently overexpressed in cancerous cells. B) are cancer-causing genes introduced into cells by viruses. C) can encode proteins that promote DNA repair or cell-cell adhesion. D) often encode proteins that stimulate the cell cycle. E) all of the above

C) can encode proteins that promote DNA repair or cell-cell adhesion.

In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage? A) regulation via acetylation of histones B) positive control mechanisms rather than negative C) control of more than one gene in an operon D) reliance on transcription activators E) utilization of eukaryotic polymerases

C) control of more than one gene in an operon

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to A) insert the fragments cut with X directly into the plasmid without cutting the plasmid. B) cut the plasmid with restriction enzyme X and insert the fragments cut with Y into the plasmid. C) cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme. D) cut the plasmid twice with restriction enzyme Y and ligate the two fragments onto the ends of the DNA fragments cut with restriction enzyme X. E) cut the plasmid with enzyme X and then insert the gene into the plasmid.

C) cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

One of the hopes for use of recent knowledge gained about non-coding RNAs lies with the possibilities for their use in medicine. Of the following scenarios for future research, which would you expect to gain most from RNAs? A) exploring a way to turn on the expression of pseudogenes B) targeting siRNAs to disable the expression of an allele associated with autosomal recessive disease C) targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease D) creating knock-out organisms that can be useful for pharmaceutical drug design E) looking for a way to prevent viral DNA from causing infection in humans

C) targeting siRNAs to disable the expression of an allele associated with autosomal dominant disease

Which of the following is an example of post-transcriptional control of gene expression? A) the addition of methyl groups to cytosine bases of DNA B) the binding of transcription factors to a promoter C) the removal of introns and splicing together of exons D) gene amplification during a stage in development E) the folding of DNA to form heterochromatin

C) the removal of introns and splicing together of exons

The researcher in question measures the amount of new polypeptide production in embryos from 2—8 hours following fertilization and the results show a steady and significant rise in polypeptide concentration over that time. The researcher concludes that A) his measurement skills must be faulty. B) the results are due to building new cell membranes to compartmentalize dividing nuclei. C) the resulting new polypeptides are due to translation of maternal mRNAs. D) the new polypeptides were inactive and not measurable until fertilization. E) polypeptides were attached to egg membranes until this time.

C) the resulting new polypeptides are due to translation of maternal mRNAs.

A cell that remains entirely flexible in its developmental possibilities is said to be A) differentiated. B) determined. C) totipotent. D) genomically equivalent. E) epigenetic.

C) totipotent.

In most cases, differentiation is controlled at which level? A) replication of the DNA B) nucleosome formation C) transcription D) translation E) post-translational activation of the proteins

C) transcription

Bioinformatics includes all of the following except A) using computer programs to align DNA sequences. B) analyzing protein interactions in a species. C) using molecular biology to provide biological information to a system so that it gets expressed. D) development of computer-based tools for genome analysis. E) use of mathematical tools to make sense of biological systems.

C) using molecular biology to provide biological information to a system so that it gets expressed.

How is a physical map of the genome of an organism achieved? A) using recombination frequency B) using very high-powered microscopy C) using restriction enzyme cutting sites D) using sequencing of nucleotides E) using DNA fingerprinting via electrophoresis

C) using restriction enzyme cutting sites

A mutation in this section of DNA could influence the biding of RNA polymerase to the DNA A. operon B. inducer C. promoter D. repressor E. corepressor

C. promoter

Which of the following is a major distinction between a transposon and a retrotransposon? A) A transposon always leaves a copy of itself at its original position and a retrotransposon does not. B) A retrotransposon always uses the copy-paste mechanism, while a transposon uses cut and paste mechanism. C) A transposon is related to a virus and a retrotransposon is not. D) A transposon moves via a DNA intermediate and a retrotransposon via an RNA intermediate. E) The positioning of a transposon copy is transient while that of a retrotransposon is permanent.

D) A transposon moves via a DNA intermediate and a retrotransposon via an RNA intermediate.

Which statement about variation is true? A) All phenotypic variation is the result of genotypic variation. B) All genetic variation produces phenotypic variation. C) All nucleotide variability results in neutral variation. D) All new alleles are the result of nucleotide variability. E) All geographic variation results from the existence of clines.

D) All new alleles are the result of nucleotide variability.

In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. These colors come from carotenoid pigments that are found in the birds diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male s feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food -gathering efforts (all other factors being equal). During breeding season, one should expect female house finches to prefer to mate with males with the brightest red feathers. Which of the following is true of this situation? A) Alleles that promote more efficient acquisition of carotenoid-containing foods by males should increase over the course of generations. B) Alleles that promote more effective deposition of carotenoid pigments in the feathers of males should increase over the course of generations. C) There should be directional selection for bright red feathers in males. D) All three of these. E) Only B and C.

D) All three of these

The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur? A) The embryo would grow to an unusually large size. B) The embryo would grow extra wings and legs. C) The embryo would probably show no anterior development and die. D) Anterior structures would form in both sides of the embryo. E) The embryo would develop normally.

D) Anterior structures would form in both sides of the embryo.

Which group is composed entirely of individuals who maintained that species are fixed (i.e., unchanging)? A) Aristotle, Cuvier, and Lamarck B) Linnaeus, Cuvier, and Lamarck C) Lyell, Linnaeus, and Lamarck D) Aristotle, Linnaeus, and Cuvier E) Hutton, Lyell, and Darwin

D) Aristotle, Linnaeus, and Cuvier

If she moves the promoter for the lac operon to the region between the beta galactosidase gene and the permease gene, which of the following would be likely? A) Three structural genes will no longer be expressed. B) RNA polymerase will no longer transcribe permease. C) The operon will no longer be inducible. D) Beta galactosidase will be produced. E) The cell will continue to metabolize but more slowly.

D) Beta galactosidase will be produced.

Why might the cricket genome have 11 times as many base pairs than that of Drosophila melanogaster? A) The two insect species evolved at very different geologic eras. B) Crickets have higher gene density. C) Drosophila are more complex organisms. D) Crickets must have more non-coding DNA. E) Crickets must make many more proteins.

D) Crickets must have more non-coding DNA.

Two potential devices that eukaryotic cells use to regulate transcription are A) DNA methylation and histone amplification. B) DNA amplification and histone methylation. C) DNA acetylation and methylation. D) DNA methylation and histone acetylation. E) histone amplification and DNA acetylation.

D) DNA methylation and histone acetylation.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island s lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. If a speciation event occurred on Sao Tomé, producing D. santomea from a parent colony of D. yakuba, then which terms apply? I. macroevolution II. allopatric speciation III. sympatric speciation A) I only B) II only C) I & II D) I & III

D) I & III

Sponges are known to contain a single Hox gene. Most invertebrates have a cluster of 10 similar Hox genes, all located on the same chromosome. Most vertebrates have four such clusters of Hox genes, located on four non-homologous chromosomes. The process responsible for the change in number of Hox genes from sponges to invertebrates was most likely __________, whereas a different process that could have potentially contributed to the cluster s presence on more than one chromosome was __________. I. binary fission II. translation III. gene duplication IV. non-disjunction V. transcription A) I, II B) II, III C) II, V D) III, IV E) III, V

D) III, IV

How does active CAP induce expression of the genes of the lactose operon? A) It terminates production of repressor molecules. B) It degrades the substrate allolactose. C) It stimulates splicing of the encoded genes. D) It stimulates the binding of RNA polymerase to the promoter. E) It binds steroid hormones and controls translation.

D) It stimulates the binding of RNA polymerase to the promoter.

Which of the following describes the function of an enzyme known as Dicer? A) It degrades single-stranded DNA. B) It degrades single-stranded mRNA. C) It degrades mRNA with no poly(A) tail. D) It trims small double-stranded RNAs into molecules that can block translation. E) It chops up single-stranded DNAs from infecting viruses.

D) It trims small double-stranded RNAs into molecules that can block translation.

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur? A) Methylated DNA should become fixed in the gene pools of bacterial species. B) Nonmethylated DNA should become fixed in the gene pools of bacteriophages. C) Methylated DNA should become fixed in the gene pools of bacteriophages. D) Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time. E) Both A and B are correct.

D) Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time.

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection? A) Small birds gaining larger beaks by exercising their mouth parts. B) Small birds mutating their beak genes with the result that later-generation offspring have larger beaks. C) Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks. D) More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks. E) Larger birds eating less so smaller birds can survive.

D) More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.

Which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations? A) Mutation B) Non-random mating C) Gene flow D) Natural selection E) Genetic drift

D) Natural selection

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) Larger doses of DDT should have been applied. B) All habitats should have received applications of DDT at about the same time. C) The frequency of DDT application should have been higher. D) None of the individual insects should have possessed genomes that made them resistant to DDT. E) DDT application should have been continual.

D) None of the individual insects should have possessed genomes that made them resistant to DDT.

Which statement best describes the evolution of pesticide resistance in a population of insects? A) Individual members of the population slowly adapt to the presence of the chemical by striving to meet the new challenge. B) All insects exposed to the insecticide begin to use a formerly silent gene to make a new enzyme that breaks down the insecticide molecules. C) Insects observe the behavior of other insects that survive pesticide application, and adjust their own behaviors to copy those of the survivors. D) Offspring of insects that are genetically resistant to the pesticide become more abundant as the susceptible insects die off.

D) Offspring of insects that are genetically resistant to the pesticide become more abundant as the susceptible insects die off.

Which of the following observations helped Darwin shape his concept of descent with modification? A) Species diversity declines farther from the equator. B) Fewer species live on islands than on the nearest continents. C) Birds can be found on islands located farther from the mainland than the birds maximum nonstop flight distance. D) South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe. E) Earthquakes reshape life by causing mass extinctions.

D) South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

The researcher continues to study the reactions of the embryo to these new proteins and you hypothesize that he is most likely to see which of the following (while embryonic genes are still not being expressed)? A) The cells begin to differentiate. B) The proteins are evenly distributed throughout the embryo. C) Larval features begin to make their appearance. D) Spatial axes (anterior posterior, etc.) begin to be determined. E) The embryo begins to lose cells due to apoptosis from no further gene expression.

D) Spatial axes (anterior posterior, etc.) begin to be determined.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have A) T2 protein and T4 DNA. B) T2 protein and T2 DNA. C) a mixture of the DNA and proteins of both phages. D) T4 protein and T4 DNA. E) T4 protein and T2 DNA.

D) T4 protein and T4 DNA.

If she moves the operator to the far end of the operon (past the transacetylase gene), which of the following would likely occur when the cell is exposed to lactose? A) The inducer will no longer bind to the repressor. B) The repressor will no longer bind to the operator. C) The operon will never be transcribed. D) The structural genes will be transcribed continuously. E) The repressor protein will no longer be produced.

D) The structural genes will be transcribed continuously.

The researcher measures the concentration of the polypeptides from different regions in the early embryo and finds the following pattern (darker shading = greater concentration): Which of the following would be his most logical assumption? A) The substance has moved quickly from region 5 to region 1. B) Some other material in the embryo is causing accumulation in region 1 due to differential binding. C) The cytosol is in constant movement, dispersing the polypeptide. D) The substance is produced in region 1 and diffuses toward region 5. E) The substance must have entered the embryo from the environment near region 1.

D) The substance is produced in region 1 and diffuses toward region 5.

Which of the events described below agrees with the idea of catastrophism? A) The gradual uplift of the Himalayas by the collision of the Australian crustal plate with the Eurasian crustal plate B) The formation of the Grand Canyon by the Colorado River over millions of years C) The gradual deposition of sediments many kilometers thick on the floors of seas and oceans D) The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial body with Earth E) The development of the Galapagos Islands from underwater seamounts over millions of years

D) The sudden demise of the dinosaurs, and various other groups, by the impact of a large extraterrestrial body with Earth

Which of the following pairs of structures is least likely to represent homology? A) The wings of a bat and the arms of a human B) The hemoglobin of a baboon and that of a gorilla C) The mitochondria of a plant and those of an animal D) The wings of a bird and those of an insect E) The brain of a cat and that of a dog

D) The wings of a bird and those of an insect

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 is the frequency of the allele for brown feathers highest? 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.

D) They are all the same.

Which of the following is one of the technical reasons why gene therapy is problematic? A) Most cells with an engineered gene do not produce gene product. B) Most cells with engineered genes overwhelm other cells in a tissue. C) Cells with transferred genes are unlikely to replicate. D) Transferred genes may not have appropriately controlled activity. E) mRNA from transferred genes cannot be translated.

D) Transferred genes may not have appropriately controlled activity.

Which statement about natural selection is most correct? A) Adaptations beneficial in one habitat should generally be beneficial in all other habitats as well. B) Different species that occupy the same habitat will adapt to that habitat by undergoing the same genetic changes. C) Adaptations beneficial at one time should generally be beneficial during all other times as well. D) Well-adapted individuals leave more offspring, and thus contribute more to the next generation s gene pool, than do poorly adapted individuals. E) Natural selection is the sole means by which populations can evolve.

D) Well-adapted individuals leave more offspring, and thus contribute more to the next generation s gene pool, than do poorly adapted individuals.

Charles Darwin was the first person to propose A) that evolution occurs. B) a mechanism for how evolution occurs. C) that the Earth is older than a few thousand years. D) a mechanism for evolution that was supported by evidence. E) a way to use artificial selection as a means of domesticating plants and animals.

D) a mechanism for evolution that was supported by evidence.

In recombinant DNA methods, the term vector can refer to A) the enzyme that cuts DNA into restriction fragments. B) the sticky end of a DNA fragment. C) a RFLP marker. D) a plasmid used to transfer DNA into a living cell. E) a DNA probe used to identify a particular gene.

D) a plasmid used to transfer DNA into a living cell.

Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because A) it allows researchers to use the sequence to build a better nematode, resistant to disease. B) it allows research on a group of organisms we do not usually care much about. C) the nematode is a good animal model for trying out cures for viral illness. D) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates. E) a sequence that is found to have no introns in the nematode genome is likely to have acquired the introns from higher organisms.

D) a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.

Emerging viruses arise by A) mutation of existing viruses. B) the spread of existing viruses to new host species. C) the spread of existing viruses more widely within their host species. D) all of the above E) none of the above

D) all of the above

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then the A) amino acid inactivates the repressor. B) enzymes produced are called inducible enzymes. C) repressor is active in the absence of the amino acid. D) amino acid acts as a corepressor. E) amino acid turns on transcription of the operon.

D) amino acid acts as a corepressor.

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and A) their chromosomes are no longer homologous enough to permit meiosis. B) a constant number of viable, fertile hybrids is produced over the course of generations. C) the hybrid zone is inhospitable to hybrid survival. D) an increasing number of viable, fertile hybrids is produced over the course of generations E) a decreasing number of viable, fertile hybrids is produced over the course of generations.

D) an increasing number of viable, fertile hybrids is produced over the course of generations

The theory of evolution is most accurately described as A) an educated guess about how species originate. B) one possible explanation, among several scientific alternatives, about how species have come into existence. C) an opinion that some scientists hold about how living things change over time. D) an overarching explanation, supported by much evidence, for how populations change over time. E) an idea about how acquired characteristics are passed on to subsequent generations.

D) an overarching explanation, supported by much evidence, for how populations change over time.

Steroid hormones produce their effects in cells by A) activating key enzymes in metabolic pathways. B) activating translation of certain mRNAs. C) promoting the degradation of specific mRNAs. D) binding to intracellular receptors and promoting transcription of specific genes. E) promoting the formation of looped domains in certain regions of DNA.

D) binding to intracellular receptors and promoting transcription of specific genes.

There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans, or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept is most applicable in this example? A) phylogenetic B) ecological C) morphological D) biological

D) biological

How might identical and obviously duplicated gene sequences have gotten from one chromosome to another? A) by normal meiotic recombination B) by normal mitotic recombination between sister chromatids C) by transcription followed by recombination D) by chromosomal translocation E) by deletion followed by insertion

D) by chromosomal translocation

Which of the following most correctly describes a shotgun technique for sequencing a genome? A) genetic mapping followed immediately by sequencing B) physical mapping followed immediately by sequencing C) cloning large genome fragments into very large vectors such as YACs, followed by sequencing D) cloning several sizes of fragments into various size vectors, ordering the clones, and then sequencing them E) cloning the whole genome directly, from one end to the other

D) cloning several sizes of fragments into various size vectors, ordering the clones, and then sequencing them

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator? A) irreversible binding of the repressor to the promoter B) reduced transcription of the operon s genes C) buildup of a substrate for the pathway controlled by the operon D) continuous transcription of the operon s genes E) overproduction of catabolite activator protein (CAP)

D) continuous transcription of the operons genes

Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of life? A) re-infection by a closely related herpesvirus of a different strain B) re-infection by the same herpesvirus strain C) co-infection with an unrelated virus that causes the same symptoms D) copies of the herpesvirus genome permanently maintained in host nuclei E) copies of the herpesvirus genome permanently maintained in host cell cytoplasm

D) copies of the herpesvirus genome permanently maintained in host nuclei

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island s lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. The observation that island D. yakuba are more closely related to mainland D. yakuba than island D. yakuba are to D. santomea is best explained by proposing that D. santomea A) descended from a now-extinct, non-African fruit fly. B) arose de novo; that is, had no ancestors. C) descended from a single colony of D. yakuba, which had been introduced from elsewhere, with no subsequent colonization events. D) descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.

D) descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.

A certain species of land snail exists as either a cream color or a solid brown color. Intermediate individuals are relatively rare. Which of the following terms best describes this? A) artificial selection B) directional selection C) stabilizing selection D) disruptive selection E) sexual selection

D) disruptive selection

Which describes an African butterfly species that exists in two strikingly different color patterns? A) artificial selection B) directional selection C) stabilizing selection D) disruptive selection E) sexual selection

D) disruptive selection

Genomic imprinting, DNA methylation, and histone acetylation are all examples of A) genetic mutation. B) chromosomal rearrangements. C) karyotypes. D) epigenetic phenomena. E) translocation.

D) epigenetic phenomena.

The constantly changing nature of the Appalachian ground crickets (Allonemobius fasciatus and Allonemobius socius) hybrid zone favors A) no gene flow between the two gene pools. B) little gene flow between the two gene pools. C) increased levels of gene flow between the two gene pools. D) extinction of both species as the hybrids persist.

D) extinction of both species as the hybrids persist.

Differentiation of cells is not easily reversible because it involves A) changes in the nucleotide sequence of genes within the genome. B) changes in chromatin structure that make certain regions of the genome more accessible. C) chemical modifications of histones and DNA methylation. D) frameshift mutations and inversions. E) excision of some coding sequences.

D) frameshift mutations and inversions.

In 1997, Dolly the sheep was cloned. Which of the following processes was used? A) use of mitochondrial DNA from adult female cells of another ewe B) replication and dedifferentiation of adult stem cells from sheep bone marrow C) separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe D) fusion of an adult cell s nucleus with an enucleated sheep egg, followed by incubation in a surrogate E) isolation of stem cells from a lamb embryo and production of a zygote equivalent

D) fusion of an adult cell s nucleus with an enucleated sheep egg, followed by incubation in a surrogate

Which of the following separates molecules by movement due to size and electrical charge? A) restriction enzymes B) gene cloning C) DNA ligase D) gel electrophoresis E) reverse transcriptase

D) gel electrophoresis

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms? A) reduced hybrid fertility B) hybrid breakdown C) mechanical isolation D) habitat isolation E) gametic isolation

D) habitat isolation

Gene therapy A) has proven to be beneficial to HIV patients. B) involves replacement of a defective allele in sex cells. C) cannot be used to correct genetic disorders. D) had apparent success in treating disorders involving bone marrow cells. E) is a widely accepted procedure.

D) had apparent success in treating disorders involving bone marrow cells.

Muscle cells and nerve cells in one species of animal owe their differences in structure to A) having different genes. B) having different chromosomes. C) using different genetic codes. D) having different genes expressed. E) having unique ribosomes.

D) having different genes expressed.

One hereditary disease in humans, called xeroderma pigmentosum (XP), makes homozygous individuals exceptionally susceptible to UV-induced mutation damage in the cells of exposed tissue, especially skin. Without extraordinary avoidance of sunlight exposure, patients soon succumb to numerous skin cancers. Which of the following best describes this phenomenon? A) inherited cancer taking a few years to be expressed B) embryonic or fetal cancer C) inherited predisposition to mutation D) inherited inability to repair UV-induced mutation E) susceptibility to chemical carcinogens

D) inherited inability to repair

Sexual dimorphism is most often a result of A) pansexual selection. B) stabilizing selection. C) intrasexual selection. D) intersexual selection. E) artificial selection.

D) intersexual selection.

These genes form gradients and help establish the axes and other features of an embryo: A) homeotic genes B) segmentation genes C) egg-polarity genes D) morphogens E) inducers

D) morphogens

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use? A) biological B) phylogenetic C) ecological D) morphological

D) morphological

If two genes from one RNA molecule become detached and then, as a unit, get attached to one end of the other RNA molecule within a single HIV particle, which of these is true? A) There are now fewer genes within the viral particle. B) There are now more genes within the viral particle. C) A point substitution mutation has occurred in the retroviral genome. D) The retroviral equivalent of crossing-over has occurred, no doubt resulting in a heightened positive effect. E) One of the RNA molecules has experienced gene duplication as the result of translocation.

E) One of the RNA molecules has experienced gene duplication as the result of translocation.

Which uses reverse transcriptase to make cDNA followed by amplification? A) Southern blotting B) Northern blotting C) Western blotting D) Eastern blotting E) RT-PCR

E) RT-PCR

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

E) Relationships between DNA sequences among the species did not match relationships between skeletal patterns.

Which of the following statements about speciation is correct? A) The goal of natural selection is speciation. B) When reunited, two allopatric populations will not interbreed. C) Natural selection chooses the reproductive barriers for populations. D) Prezygotic reproductive barriers usually evolve before postzygotic barriers. E) Speciation is a basis for understanding macroevolution.

E) Speciation is a basis for understanding macroevolution.

If she moves the repressor gene (lac I), along with its promoter, to a position at some several thousand base pairs away from its normal position, which will you expect to occur? A) The repressor will no longer be made. B) The repressor will no longer bind to the operator. C) The repressor will no longer bind to the inducer. D) The lac operon will be expressed continuously. E) The lac operon will function normally.

E) The lac operon will function normally.

Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host? A) It is able to spread to a large number of new hosts quickly because the new hosts have no immunological memory of them. B) The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts. C) A change in environmental conditions such as weather patterns quickly forces the new virus to invade new areas. D) Sporadic outbreaks will be followed almost immediately by a widespread pandemic. E) The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

E) The newly emerging virus will die out rather quickly or will mutate to be far less lethal.

What is the most probable explanation for the continued presence of pseudogenes in a genome such as our own? A) They are genes that had a function at one time, but that have lost their function because they have been translocated to a new location. B) They are genes that have accumulated mutations to such a degree that they would code for different functional products if activated. C) They are duplicates or near duplicates of functional genes but cannot function because they would provide inappropriate dosage of protein products. D) They are genes with significant inverted sequences. E) They are genes that are not expressed, even though they have nearly identical sequences to expressed genes.

E) They are genes that are not expressed, even though they have nearly identical sequences to expressed genes.

Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory? A) Viruses contain either DNA or RNA. B) Viruses are enclosed in protein capsids rather than plasma membranes. C) Viruses can reproduce only inside host cells. D) Viruses can infect both prokaryotic and eukaryotic cells. E) Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.

E) Viral genomes are usually more similar to the genome of the host cell than to the genomes of viruses that infect other cell types.

A researcher needs to clone a sequence of part of a eukaryotic genome in order to express the sequence and to modify the polypeptide product. She would be able to satisfy these requirements by using which of the following vectors? A) a bacterial plasmid B) BAC to accommodate the size of the sequence C) a modified bacteriophage D) a human chromosome E) a YAC with appropriate cellular enzymes

E) a YAC with appropriate cellular enzymes

Although quite different in structure, plants and animals share some basic similarities in their development, such as A) the importance of cell and tissue movements. B) the importance of selective cell enlargement. C) the importance of homeobox-containing homeotic genes. D) a common evolutionary origin of the complete developmental program. E) a cascade of transcription factors that regulate gene expression on a finer and finer scale.

E) a cascade of transcription factors that regulate gene expression on a finer and finer scale.

HIV has 9 genes in its RNA genome. Every HIV particle contains two RNA molecules, each molecule containing all 9 genes. If, for some reason, the two RNA molecules within a single HIV particle do not have identical sequences, then which of these terms can be applied due to the existence of the non-identical regions? A) homozygous B) gene variability C) nucleotide variability D) average heterozygosity E) all except A

E) all except A

Which of the following can contribute to the development of cancer? A) random spontaneous mutations B) mutations caused by X-rays C) transposition D) chromosome translocations E) all of the above

E) all of the above

Which of these is the smallest unit upon which natural selection directly acts? A) a species gene frequency B) a population s gene frequency C) an individual s genome D) an individual s genotype E) an individual s phenotype

E) an individual s phenotype

As a young biologist, Charles Darwin had expected the living plants of temperate South America would resemble those of temperate Europe, but he was surprised to find that they more closely resembled the plants of tropical South America. The biological explanation for this observation is most properly associated with the field of A) meteorology. B) embryology. C) vertebrate anatomy. D) bioengineering. E) biogeography.

E) biogeography.

If the original finches that had been blown over to the Galapagos from South America had already been genetically different from the parental population of South American finches, even before adapting to the Galapagos, this would have been an example of A) genetic drift. B) bottleneck effect. C) founders effect. D) all three of these E) both A and C

E) both A and C

In eukaryotes, transcription is generally associated with A) euchromatin only. B) heterochromatin only. C) very tightly packed DNA only. D) highly methylated DNA only. E) both euchromatin and histone acetylation.

E) both euchromatin and histone acetylation.

Speciation A) occurs at such a slow pace that no one has ever observed the emergence of new species. B) occurs only by the accumulation of genetic change over vast expanses of time. C) must begin with the geographic isolation of a small, frontier population. D) proceeds at a uniform tempo across all taxa. E) can involve changes involving a single gene.

E) can involve changes involving a single gene.

Yeast artificial chromosomes contain which of the following elements? A) centromere only B) telomeres only C) origin of replication only D) centromeres and telomeres only E) centromere, telomeres, and an origin of replication

E) centromere, telomeres, and an origin of replication

Genetic engineering is being used by the pharmaceutical industry. Which of the following is not currently one of the uses? A) production of human insulin B) production of human growth hormone C) production of tissue plasminogen activator D) genetic modification of plants to produce vaccines E) creation of products that will remove poisons from the human body

E) creation of products that will remove poisons from the human body

Several of the different globin genes are expressed in humans, but at different times in development. What mechanism could allow for this? A) exon shuffling B) intron activation C) pseudogene activation D) differential translation of mRNAs E) differential gene regulation over time

E) differential gene regulation over time

Natural selection is most nearly the same as A) diploidy. B) gene flow. C) genetic drift. D) non-random mating. E) differential reproductive success.

E) differential reproductive success.

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of A) sexual selection. B) disruptive selection. C) balancing selection. D) stabilizing selection. E) frequency-dependent selection.

E) frequency-dependent selection.

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing A) non-random mating. B) geographic isolation. C) genetic drift. D) mutations. E) gene flow.

E) gene flow.

Forms of the ras protein found in tumors usually cause which of the following? A) DNA replication to stop B) DNA replication to be hyperactive C) cell-to-cell adhesion to be nonfunctional D) cell division to cease E) growth factor signaling to be hyperactive

E) growth factor signaling to be hyperactive

Multigene families are A) groups of enhancers that control transcription. B) usually clustered at the telomeres. C) equivalent to the operons of prokaryotes. D) sets of genes that are coordinately controlled. E) identical or similar genes that have evolved by gene duplication.

E) identical or similar genes that have evolved by gene duplication.

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see? A) increased chromatin condensation B) decreased chromatin concentration C) abnormalities of mouse embryos D) decreased binding of transcription factors E) inactivation of the selected genes

E) inactivation of the selected genes

If glucose is available in the environment of E. coli, the cell responds with very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect would then be a measurable effect? A) decreased concentration of the lac enzymes B) increased concentration of the trp enzymes C) decreased binding of the RNA polymerase to sugar metabolism-related promoters D) decreased concentration of alternative sugars in the cell E) increased concentrations of sugars such as arabinose in the cell

E) increased concentrations of sugars such as arabinose in the cell

Natural selection changes allele frequencies in populations because some __________ survive and reproduce more successfully than others. A) alleles B) loci C) gene pools D) species E) individuals

E) individuals

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

E) individuals adapt to their environments and, thereby, evolve.

When we say that an individual organism has a greater fitness than another individual, we specifically mean that the organism A) lives longer than others of its species. B) competes for resources more successfully than others of its species. C) mates more frequently than others of its species. D) utilizes resources more efficiently than other species occupying similar niches. E) leaves more viable offspring than others of its species.

E) leaves more viable offspring than others of its species.

Males of one species are too small to perform amplexus (an action that stimulates ovulation) with females of all other species. A) behavioral B) gametic C) habitat D) temporal E) mechanical

E) mechanical

The biggest problem with the shotgun technique is its tendency to underestimate the size of the genome. Which of the following might best account for this? A) skipping some of the clones to be sequenced B) missing some of the overlapping regions of the clones C) counting some of the overlapping regions of the clones twice D) having some of the clones die during the experiment and therefore not be represented E) missing some duplicated sequences

E) missing some duplicated sequences

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Which is a likely explanation for the lack of transgene expression in the fifth cell line? A) A transgene integrated into a heterochromatic region of the genome. B) A transgene integrated into a euchromatic region of the genome. C) The transgene was mutated during the process of integration into the host cell genome. D) The host cell lacks the enzymes necessary to express the transgene. E) A transgene integrated into a region of the genome characterized by high histone acetylation.

A) A transgene integrated into a heterochromatic region of the genome.

There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception? A) Advantageous alleles do not arise on demand. B) A population s evolution is limited by historical constraints. C) Adaptations are often compromises. D) Evolution can be influenced by environmental change.

A) Advantageous alleles do not arise on demand.

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

A) All variation between individuals is due only to environmental factors.

Which of these variables is likely to undergo the largest change in value as the result of a mutation that introduces a brand-new allele into a population s gene pool at a locus that had formerly been fixed? A) Average heterozygosity B) Nucleotide variability C) Geographic variability D) Average number of loci

A) Average heterozygosity

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) Characteristics acquired during an organism s life are generally not passed on through genes. B) Spontaneous mutations can result in the appearance of new traits. C) Only favorable adaptations have survival value. D) Disuse of an organ may lead to its eventual disappearance. E) Overproduction of offspring leads to a struggle for survival.

A) Characteristics acquired during an organism s life are generally not passed on through genes.

What was the prevailing notion prior to the time of Lyell and Darwin? A) Earth is a few thousand years old, and populations are unchanging. B) Earth is a few thousand years old, and populations gradually change. C) Earth is millions of years old, and populations rapidly change. D) Earth is millions of years old, and populations are unchanging. E) Earth is millions of years old, and populations gradually change.

A) Earth is a few thousand years old, and populations are unchanging.

What is the difference between a linkage map and a physical map? A) For a linkage map, markers are spaced by recombination frequency, whereas for a physical map they are spaced by numbers of base pairs (bp). B) For a physical map, the ATCG order and sequence must be achieved, but not for the linkage map. C) For a linkage map, it is shown how each gene is linked to every other gene. D) For a physical map, the distances must be calculable in units such as nanometers. E) There is no difference between the two except in the type of pictorial representation.

A) For a linkage map, markers are spaced by recombination frequency, whereas for a physical map they are spaced by numbers of base pairs (bp).

Which of the following must exist in a population before natural selection can act upon that population? A) Genetic variation among individuals B) Variation among individuals caused by environmental factors C) Sexual reproduction D) B and C only E) A, B, and C

A) Genetic variation among individuals

The first cell whose entire genome was sequenced was which of the following? A) H. influenzae in 1995 B) H. sapiens in 2001 C) rice in 1955 D) tobacco mosaic virus E) HIV in 1998

A) H. influenzae in 1995

81) Which of the following is characteristic of the product of the p53 gene? A) It is an activator for other genes. B) It speeds up the cell cycle. C) It causes cell death via apoptosis. D) It allows cells to pass on mutations due to DNA damage. E) It slows down the rate of DNA replication by interfering with the binding of DNA polymerase.

A) It is an activator for other genes.

Scientists developed a set of guidelines to address the safety of DNA technology. Which of the following is one of the adopted safety measures? A) Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory. B) Genetically modified organisms are not allowed to be part of our food supply. C) Transgenic plants are engineered so that the plant genes cannot hybridize. D) Experiments involving HIV or other potentially dangerous viruses have been banned. E) Recombinant plasmids cannot be replicated.

A) Microorganisms used in recombinant DNA experiments are genetically crippled to ensure that they cannot survive outside of the laboratory.

The gene for which protein would most likely be expressed as a result of MyoD activity? A) myosin B) crystallin C) albumin D) hemoglobin E) DNA polymerase

A) Myosin

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. Which population is most likely to be subject to the bottleneck effect? 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.

A) Population A.

The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA is called A) RNA interference. B) RNA obstruction. C) RNA blocking. D) RNA targeting. E) RNA disposal.

A) RNA interference.

The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is A) reinforcement. B) fusion. C) stability. D) geographic isolation. E) polyploidy.

B) fusion.

In comparing the genomes of humans and those of other higher primates, it is seen that humans have a large metacentric pair we call chromosome #2 among our 46 chromosomes, while the other primates of this group have 48 chromosomes and any pair like the human #2 pair is not present; instead the primate groups each have two pairs of midsize acrocentric chromosomes. What is the most likely explanation? A) The ancestral organism had 48 chromosomes and at some point a centric fusion event occurred and provided some selective advantage. B) The ancestral organism had 46 chromosomes, but primates evolved when one of the pairs broke in half. C) At some point in evolution, human ancestors and primate ancestors were able to mate and produce fertile offspring, making a new species. D) Chromosome breakage results in additional centromeres being made in order for meiosis to proceed successfully. E) Transposable elements transferred significantly large segments of the chromosomes to new locations.

A) The ancestral organism had 48 chromosomes and at some point a centric fusion event occurred and provided some selective advantage.

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding? A) The cells from the two sources exhibit different patterns of DNA methylation. B) Adult stem cells have more DNA nucleotides than their counterparts. C) The two kinds of cells have virtually identical gene expression patterns in microarrays. D) The non-stem cells have fewer repressed genes. E) The non-stem cells have lost the promoters for more genes.

A) The cells from the two sources exhibit different patterns of DNA methylation.

What is it about short tandem repeat DNA that makes it useful for DNA fingerprinting? A) The number of repeats varies widely from person to person or animal to animal. B) The sequence of DNA that is repeated varies significantly from individual to individual. C) The sequence variation is acted upon differently by natural selection in different environments. D) Every racial and ethnic group has inherited different short tandem repeats.

A) The number of repeats varies widely from person to person or animal to animal.

Bird guides once listed the myrtle warbler and Audubon s warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification? A) The two forms interbreed often in nature, and their offspring have good survival and reproduction. B) The two forms live in similar habitats. C) The two forms have many genes in common. D) The two forms have similar food requirements. E) The two forms are very similar in coloration.

A) The two forms interbreed often in nature, and their offspring have good survival and reproduction.

What do gap genes, pair-rule genes, segment polarity genes, and homeotic genes all have in common? A) Their products act as transcription factors. B) They have no counterparts in animals other than Drosophila. C) Their products are all synthesized prior to fertilization. D) They act independently of other positional information. E) They apparently can be activated and inactivated at any time of the fly s life.

A) Their products act as transcription factors.

Which of the following statements describes proto-oncogenes? A) They can code for proteins associated with cell growth. B) They are introduced to a cell initially by retroviruses. C) They are produced by somatic mutations induced by carcinogenic substances. D) Their normal function is to suppress tumor growth E) They are underexpressed in cancer cells

A) They can code for proteins associated with cell growth.

Why are viruses referred to as obligate parasites? A) They cannot reproduce outside of a host cell. B) Viral DNA always inserts itself into host DNA. C) They invariably kill any cell they infect. D) They can incorporate nucleic acids from other viruses. E) They must use enzymes encoded by the virus itself.

A) They cannot reproduce outside of a host cell.

Mules are relatively long-lived and hardy organisms that cannot, generally speaking, perform successful meiosis. Consequently, which statement about mules is true? A) They have a relative evolutionary fitness of zero. B) Their offspring have less genetic variation than the parents. C) Mutations cannot occur in their genomes. D) If crossing-over happens in mules, then it must be limited to prophase of mitosis. E) When two mules interbreed, genetic recombination cannot occur by meiotic crossing over, but only by the act of fertilization.

A) They have a relative evolutionary fitness of zero.

What is generally true of two very closely related species that have diverged from each other quite recently? A) They shared a common ancestor recently in evolutionary time. B) Genes are unable to pass from one species gene pool to the other s gene pool. C) They are unable to produce hybrid offspring upon interbreeding. D) Their reproductive isolation from each other is complete.

A) They shared a common ancestor recently in evolutionary time.

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

A) a cline.

Which of the following is most likely to have a small protein called ubiquitin attached to it? A) a cyclin that usually acts in G1, now that the cell is in G2 B) a cell surface protein that requires transport from the ER C) an mRNA that is leaving the nucleus to be translated D) a regulatory protein that requires sugar residues to be attached E) an mRNA produced by an egg cell that will be retained until after fertilization

A) a cyclin that usually acts in G1, now that the cell is in G2

Which of the following best describes siRNA? A) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA B) a single-stranded RNA that can, where it has internal complementary base pairs, fold into cloverleaf patterns C) a double-stranded RNA that is formed by cleavage of hairpin loops in a larger precursor D) a portion of rRNA that allows it to bind to several ribosomal proteins in forming large or small subunits E) a molecule, known as Dicer, that can degrade other mRNA sequences

A) a short double-stranded RNA, one of whose strands can complement and inactivate a sequence of mRNA

Which of the following is the best predictor of how much damage a virus causes? A) ability of the infected cell to undergo normal cell division B) ability of the infected cell to carry on translation C) whether the infected cell produces viral protein D) whether the viral mRNA can be transcribed E) how much toxin the virus produces

A) ability of the infected cell to undergo normal cell division

In the wild, male house finches (Carpodus mexicanus) vary considerably in the amount of red pigmentation in their head and throat feathers, with colors ranging from pale yellow to bright red. These colors come from carotenoid pigments that are found in the birds diets; no vertebrates are known to synthesize carotenoid pigments. Thus, the brighter red the male s feathers are, the more successful he has been at acquiring the red carotenoid pigment by his food -gathering efforts (all other factors being equal). The situation as described in the paragraph above should select most directly against males that A) are unable to distinguish food items that are red from those of other colors. B) are older, but still healthy. C) are capable of defending only moderately sized territories. D) have slightly lower levels of testosterone during breeding season than have other males. E) have no prior experience courting female house finches.

A) are unable to distinguish food items that are red from those of other colors.

Females of one species choose mates based on song quality; females of another species choose mates on the basis of size. A) behavioral B) gametic C) habitat D) temporal E) mechanical

A) behavioral

Males of one species sing only when its predators are absent; males of another species sing only when its predators are present. A) behavioral B) gametic C) habitat D) temporal E) mechanical

A) behavioral

Which definition of evolution would have been most foreign to Charles Darwin during his lifetime? A) change in gene frequency in gene pools B) descent with modification C) the gradual change of a population s heritable traits over generations D) populations becoming better adapted to their environments over the course of generations E) the appearance of new varieties and new species with the passage of time

A) change in gene frequency in gene pools

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer? A) colorectal only B) lung and breast C) small intestinal and esophageal D) lung only E) lung and prostate

A) colorectal only

A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in A) continuous transcription of the structural gene controlled by that regulator. B) complete inhibition of transcription of the structural gene controlled by that regulator. C) irreversible binding of the repressor to the operator. D) inactivation of RNA polymerase by alteration of its active site. E) continuous translation of the mRNA because of alteration of its structure.

A) continuous transcription of the structural gene controlled by that regulator.

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) cross your flies with flies from another lab. B) reduce the number of flies that you transfer at each generation. C) transfer only the largest flies. D) change the temperature at which you rear the flies. E) shock the flies with a brief treatment of heat or cold to make them more hardy.

A) cross your flies with flies from another lab.

Which of the following serve as sources of developmental information? A) cytoplasmic determinants such as mRNAs and proteins produced before fertilization B) signal molecules produced by the maturing zygote C) ubiquitous enzymes such as DNA polymerase and DNA ligase D) paternally deposited proteins E) specific operons within the zygote genome

A) cytoplasmic determinants such as mRNAs and proteins produced before fertilization

The general process that leads to the differentiation of cells is called A) determination. B) specialization. C) identification. D) differentialization. E) cellularization.

A) determination.

The process of cellular differentiation is a direct result of A) differential gene expression. B) morphogenesis. C) cell division. D) apoptosis. E) differences in cellular genomes.

A) differential gene expression.

The fact that plants can be cloned from somatic cells demonstrates that A) differentiated cells retain all the genes of the zygote. B) genes are lost during differentiation. C) the differentiated state is normally very unstable. D) differentiated cells contain masked mRNA. E) differentiation does not occur in plants.

A) differentiated cells retain all the genes of the zygote.

A biologist discovers two populations of wolf spiders whose members appear identical. Members of one population are found in the leaf litter deep within the woods. Members of the other population are found in the grass at the edge of the woods. The biologist decides to designate the members of the two populations as two separate species. Which species concept is this biologist most closely utilizing? A) ecological B) biological C) morphological D) phylogenetic

A) ecological

In animals, embryonic stem cells differ from adult stem cells in that A) embryonic stem cells are totipotent, and adult stem cells are pluripotent. B) embryonic stem cells are pluripotent, and adult stem cells are totipotent. C) embryonic stem cells have more genes than adult stem cells. D) embryonic stem cells have fewer genes than adult stem cells. E) embryonic stem cells are localized to specific sites within the embryo, whereas adult stem cells are spread throughout the body.

A) embryonic stem cells are totipotent, and adult stem cells are pluripotent.

Homeotic genes A) encode transcription factors that control the expression of genes responsible for specific anatomical structures. B) are found only in Drosophila and other arthropods. C) are the only genes that contain the homeobox domain. D) encode proteins that form anatomical structures in the fly. E) are responsible for patterning during plant development.

A) encode transcription factors that control the expression of genes responsible for

Muscle cells differ from nerve cells mainly because they A) express different genes. B) contain different genes. C) use different genetic codes. D) have unique ribosomes. E) have different chromosomes.

A) express different genes.

Bioinformatics can be used to scan sequences for probable genes looking for start and stop sites for transcription and for translation, for probable splice sites, and for sequences known to be found in other known genes. Such sequences containing these elements are called A) expressed sequence tags. B) cDNA. C) multigene families. D) proteomes. E) short tandem repeats.

A) expressed sequence tags.

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from A) frequency-dependent selection. B) evolutionary imbalance. C) heterozygote advantage. D) neutral variation. E) genetic variation being preserved by diploidy.

A) frequency-dependent selection.

Which of these should decline in hybrid zones where reinforcement is occurring? A) gene flow between distinct gene pools B) speciation C) the genetic distinctness of two gene pools D) mutation rate E) hybrid sterility

A) gene flow between distinct gene pools

There are 40 individuals in population 1, all of which have genotype A1A1, and there are 25 individuals in population 2, all of genotype A2A2. Assume that these populations are located far from one another and that their environmental conditions are very similar. Based on the information given here, the observed genetic variation is mostly likely an example of A) genetic drift. B) gene flow. C) disruptive selection. D) discrete variation. E) directional selection.

A) genetic drift.

Which of the following can be effective in preventing viral infection in humans? A) getting vaccinated B) taking nucleoside analogs that inhibit transcription C) taking antibiotics D) applying antiseptics E) taking vitamins

A) getting vaccinated

Which of the following molecules make up the viral envelope? A) glycoproteins B) proteosugars C) carbopeptides D) peptidocarbs E) carboproteins

A) glycoproteins

Eukaryotic cells can control gene expression by which of the following mechanisms? A) histone acetylation of nucleosomes B) DNA acetylation C) RNA induced modification of chromatin structure D) repression of operons E) induction of operators in the promoter

A) histone acetylation of nucleosomes

Mutations in these genes lead to transformations in the identity of entire body parts: A) homeotic genes B) segmentation genes C) egg-polarity genes D) morphogens E) inducers

A) homeotic genes

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) humans and chimpanzees share a relatively recent common ancestor. B) humans evolved from chimpanzees. C) chimpanzees evolved from humans. D) convergent evolution led to the DNA similarities. E) humans and chimpanzees are not closely related.

A) humans and chimpanzees share a relatively recent common ancestor.

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments she succeeded in decreasing methylation of histone tails. Which of the following results would she most likely see? A) increased chromatin condensation B) decreased chromatin concentration C) abnormalities of mouse embryos D) decreased binding of transcription factors E) inactivation of the selected genes

A) increased chromatin condensation

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) common environments are inhabited by the same organisms. C) the islands were originally part of the continent. D) the island forms and mainland forms are converging. E) island forms and mainland forms have identical gene pools.

A) island forms and mainland forms descended from common ancestors.

What are prions? A) misfolded versions of normal brain protein B) tiny molecules of RNA that infect plants C) viral DNA that has had to attach itself to the host genome D) viruses that invade bacteria E) a mobile segment of DNA

A) misfolded versions of normal brain protein

In modern terminology, diversity is understood to be a result of genetic variation. Sources of variation for evolution include all of the following except A) mistakes in translation of structural genes. B) mistakes in DNA replication. C) translocations and mistakes in meiosis. D) recombination at fertilization. E) recombination by crossing over in meiosis.

A) mistakes in translation of structural genes.

In humans, the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults. This is due to A) nonidentical genes that produce different versions of globins during development. B) identical genes that generate many copies of the ribosomes needed for fetal globin production. C) pseudogenes, which interfere with gene expression in adults. D) the attachment of methyl groups to cytosine following birth, which changes the type of hemoglobin produced. E) histone proteins changing shape during embryonic development.

A) nonidentical genes that produce different versions of globins during development.

Which of the following mechanisms is (are) used to coordinately control the expression of multiple, related genes in eukaryotic cells? A) organization of the genes into clusters, with local chromatin structures influencing the expression of all the genes at once B) each of the genes sharing a common control element, allowing several activators to turn on their transcription, regardless of their location in the genome C) organizing the genes into large operons, allowing them to be transcribed as a single unit D) a single repressor able to turn off several related genes E) environmental signals that enter the cell and bind directly to their promoters

A) organization of the genes into clusters, with local chromatin structures influencing the expression of all the genes at once

Which species concept is currently most popular among most biologists? A) phylogenetic B) ecological C) biological D) morphological

A) phylogenetic

The largest unit within which gene flow can readily occur is a A) population. B) species. C) genus. D) hybrid. E) phylum.

A) population.

Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of A) post-transcriptional processing. B) electroporation. C) post-translational processing. D) nucleic acid hybridization. E) restriction fragment ligation.

A) post-transcriptional processing.

The same gene that causes various coat patterns in wild and domesticated cats also causes the cross-eyed condition in these cats, the cross-eyed condition being slightly maladaptive. In a hypothetical environment, the coat pattern that is associated with crossed eyes is highly adaptive, with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time. Which statement is supported by these observations? A) Evolution is progressive and tends toward a more perfect population. B) Phenotype is often the result of compromise. C) Natural selection reduces the frequency of maladaptive genes in populations over the course of time. D) Polygenic inheritance is generally maladaptive, and should become less common in future generations. E) In all environments, coat pattern is a more important survival factor than is eye-muscle tone.

B) Phenotype is often the result of compromise.

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

B) Poorly adapted individuals never produce offspring.

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) Population B.

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus? A) All species are fixed in the form in which they are created. B) Populations tend to increase at a faster rate than their food supply normally allows. C) Earth changed over the years through a series of catastrophic upheavals. D) The environment is responsible for natural selection. E) Earth is more than 10,000 years old.

B) Populations tend to increase at a faster rate than their food supply normally allows.

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells? A) Proto-oncogenes first arose from viral infections. B) Proto-oncogenes normally help regulate cell division. C) Proto-oncogenes are genetic junk. D) Proto-oncogenes are mutant versions of normal genes. E) Cells produce proto-oncogenes as they age.

B) Proto-oncogenes normally help regulate cell division.

Why do RNA viruses appear to have higher rates of mutation? A) RNA nucleotides are more unstable than DNA nucleotides. B) Replication of their genomes does not involve the proofreading steps of DNA replication. C) RNA viruses replicate faster. D) RNA viruses can incorporate a variety of nonstandard bases. E) RNA viruses are more sensitive to mutagens.

B) Replication of their genomes does not involve the proofreading steps of DNA replication.

Which of the following statements is true about stem cells? A) Stem cells can continually reproduce and are not subject to mitotic control. B) Stem cells can differentiate into specialized cells. C) Stem cells are found only in bone marrow. D) Stem cells are found only in the adult human brain. E) Stem cell DNA lacks introns.

B) Stem cells can differentiate into specialized cells.

Which of these is a statement that Darwin would have rejected? A) Environmental change plays a role in evolution. B) The smallest entity that can evolve is an individual organism. C) Individuals can acquire new characteristics as they respond to new environments or situations. D) Inherited variation in a population is a necessary precondition for natural selection to operate. E) Natural populations tend to produce more offspring than the environment can support.

B) The smallest entity that can evolve is an individual organism.

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) The population is undergoing genetic drift. B) The two phenotypes are about equally adaptive under laboratory conditions. C) The genotype AA is lethal. D) There has been a high rate of mutation of allele A to allele a. E) There has been sexual selection favoring allele a.

B) The two phenotypes are about equally adaptive under laboratory conditions.

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 live at great distance from each other. B) The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical. C) The sizes of the structures in adult members of both species are similar in size. D) Both species are well adapted to their particular environments. E) Both species reproduce sexually.

B) The two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.

Unequal crossing over during Prophase I can result in one sister chromosome with a deletion and another with a duplication. A mutated form of hemoglobin, known as hemoglobin Lepore, is known in the human population. Hemoglobin Lepore has a deleted set of amino acids. If it was caused by unequal crossing over, what would be an expected consequence? A) If it is still maintained in the human population, hemoglobin Lepore must be selected for in evolution. B) There should also be persons born with, if not living long lives with, an anti-Lepore mutation or duplication. C) Each of the genes in the hemoglobin gene family must show the same deletion. D) The deleted gene must have undergone exon shuffling E) The deleted region must be located in a different area of the individual s genome.

B) There should also be persons born with, if not living long lives with, an anti-Lepore mutation or duplication.

Which of the following produces multiple identical copies of a gene for basic research or for large-scale production of a gene product? A) restriction enzymes B) gene cloning C) DNA ligase D) gel electrophoresis E) reverse transcriptase

B) gene cloning

You are given an experimental problem involving control of a gene s expression in the embryo of a particular species. One of your first questions is whether the gene s expression is controlled at the level of transcription or translation. Which of the following might best give you an answer? A) You explore whether there has been alternative splicing by examining amino acid sequences of very similar proteins. B) You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same. C) You assess the position and sequence of the promoter and enhancer for this gene. D) An analysis of amino acid production by the cell shows you that there is an increase at this stage of embryonic life. E) You use an antibiotic known to prevent translation.

B) You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same.

What is bioinformatics? A) a technique using 3D images of genes in order to predict how and when they will be expressed B) a method that uses very large national and international databases to access and work with sequence information C) a software program available from NIH to design genes D) a series of search programs that allow a student to identify who in the world is trying to sequence a given species E) a procedure that uses software to order DNA sequences in a variety of comparable

B) a method that uses very large national and international databases to access and work with sequence information

Which of these is the smallest unit that natural selection can change? A) a species gene frequency B) a population s gene frequency C) an individual s genome D) an individual s genotype E) an individual s phenotype

B) a population s gene frequency

If the HMS Beagle had completely bypassed the Galapagos Islands, Darwin would have had a much poorer understanding of the A) relative stability of a well-adapted population s numbers over many generations. B) ability of populations to undergo modification as they adapt to a particular environment. C) tendency of organisms to produce the exact number of offspring that the environment can support. D) unlimited resources that support population growth in most natural environments. E) lack of genetic variation among all members of a population.

B) ability of populations to undergo modification as they adapt to a particular environment.

If a Drosophila female has a homozygous mutation for a maternal effect gene, A) she will not develop past the early embryonic stage. B) all of her offspring will show the mutant phenotype, regardless of their genotype. C) only her male offspring will show the mutant phenotype. D) her offspring will show the mutant phenotype only if they are also homozygous for the mutation. E) only her female offspring will show the mutant phenotype.

B) all of her offspring will show the mutant phenotype, regardless of their genotype.

In response to chemical signals, prokaryotes can do which of the following? A) turn off translation of their mRNA B) alter the level of production of various enzymes C) increase the number and responsiveness of their ribosomes D) inactivate their mRNA molecules E) alter the sequence of amino acids in certain proteins

B) alter the level of production of various enzymes

A hybrid zone is properly defined as A) an area where two closely related species ranges overlap. B) an area where mating occurs between members of two closely related species, producing viable offspring. C) a zone that features a gradual change in species composition where two neighboring ecosystems border each other. D) a zone that includes the intermediate portion of a cline. E) an area where members of two closely related species intermingle, but experience no gene flow.

B) an area where mating occurs between members of two closely related species, producing viable offspring.

Viral envelopes can best be analyzed with which of the following techniques? A) transmission electron microscopy B) antibodies against specific proteins not found in the host membranes C) staining and visualization with the light microscope D) use of plaque assays for quantitative measurement of viral titer E) immunofluorescent tagging of capsid proteins

B) antibodies against specific proteins not found in the host membranes

In eukaryotes, general transcription factors A) are required for the expression of specific protein-encoding genes. B) bind to other proteins or to a sequence element within the promoter called the TATA box. C) inhibit RNA polymerase binding to the promoter and begin transcribing. D) usually lead to a high level of transcription even without additional specific transcription factors. E) bind to sequences just after the start site of transcription.

B) bind to other proteins or to a sequence element within the promoter called the TATA box.

The product of the bicoid gene in Drosophila could be considered a(n) A) tissue-specific protein. B) cytoplasmic determinant. C) maternal effect. D) inductive signal. E) fertilization product.

B) cytoplasmic determinant.

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. In one set of experiments using this procedure in Drosophila, she was readily successful in increasing phosphorylation of amino acids adjacent to methylated amino acids in histone tails. Which of the following results would she most likely see? A) increased chromatin condensation B) decreased chromatin concentration C) abnormalities of mouse embryos D) decreased binding of transcription factors E) inactivation of the selected genes

B) decreased chromatin concentration

Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this? A) artificial selection B) directional selection C) stabilizing selection D) disruptive selection E) sexual selection

B) directional selection

In seed cracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population? A) disruptive selection B) directional selection C) stabilizing selection D) sexual selection E) No selection would operate because the population is in Hardy-Weinberg equilibrium.

B) directional selection

To introduce a particular piece of DNA into an animal cell, such as that of a mouse, you would find more probable success with which of the following methods? A) the shotgun approach B) electroporation followed by recombination C) introducing a plasmid into the cell D) infecting the mouse cell with a Ti plasmid E) transcription and translation

B) electroporation followed by recombination

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) Humans and bats evolved by natural selection, and whales evolved by Lamarckian mechanisms. B) Forelimb evolution was adaptive in people and bats, but not in whales. C) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy. D) Genes mutate faster in whales than in humans or bats. E) Whales are not properly classified as mammals.

C) Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.

For a repressible operon to be transcribed, which of the following must occur? A) A corepressor must be present. B) RNA polymerase and the active repressor must be present. C) RNA polymerase must bind to the promoter, and the repressor must be inactive. D) RNA polymerase cannot be present, and the repressor must be inactive. E) RNA polymerase must not occupy the promoter, and the repressor must be inactive.

C) RNA polymerase must bind to the promoter, and the repressor must be inactive.

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

C) Selection for larger female algae-eaters, bearing broods composed of more, and larger, young

If humans have 2,900 Mb, a specific member of the lily family has 120,000 Mb, and a yeast has ~13 Mb, why can t this data allow us to order their evolutionary significance? A) Size matters less than gene density. B) Size does not compare to gene density. C) Size does not vary with gene complexity. D) Size is mostly due to junk DNA. E) Size is comparable only within phyla.

C) Size does not vary with gene complexity.

Which of Darwin s ideas had the strongest connection to Darwin having read Malthus s essay on human population growth? A) Descent with modification B) Variation among individuals in a population C) Struggle for existence D) The ability of related species to be conceptualized in tree thinking E) That the ancestors of the Galapagos finches had come from the South American mainland

C) Struggle for existence

Why is it preferable to use large computers and databases in searching for individual genes, rather than testing each sequence for possible function? A) Testing for function would require too many cells. B) Testing for function would require knowing the species, its life stage, and its phylogeny. C) Testing for function would require knowing where a particular gene starts and ends and how it is regulated. D) Use of computer databases is intellectually less rigorous. E) The computer data can be sent to more labs.

C) Testing for function would require knowing where a particular gene starts and ends

In the narrow hybrid zone that separates the toad species Bombina bombina and Bombina variegata, what is true of those alleles that are unique to the parental species? A) Such alleles should be absent. B) Their allele frequency should be nearly the same as the allele frequencies in toad populations distant from the hybrid zone. C) The alleles heterozygosity should be higher among the hybrid toads there. D) Their allele frequency on one edge of the hybrid zone should roughly equal their frequency on the opposite edge of the hybrid zone.

C) The alleles heterozygosity should be higher among the hybrid toads there.

Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ? A) The appendix can be surgically removed with no immediate ill effects. B) The appendix might have been larger in fossil hominids. C) The appendix has a substantial amount of defensive lymphatic tissue. D) Individuals with a larger-than-average appendix leave fewer offspring than those with a below-average-sized appendix. E) In a million years, the human species might completely lack an appendix.

C) The appendix has a substantial amount of defensive lymphatic tissue.

One successful form of gene therapy has involved delivery of an allele for the enzyme adenosine deaminase (ADA) to bone marrow cells of a child with SCID, and delivery of these engineered cells back to the bone marrow of the affected child. What is one major reason for the success of this procedure as opposed to many other efforts at gene therapy? A) The engineered bone marrow cells from this patient can be used for any other SCID patient. B) The ADA introduced allele causes all other ADA-negative cells to die. C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow. D) No vector is required to introduce the allele into ADA-negative cells E) The immune system fails to recognize cells with the variant gene

C) The engineered cells, when reintroduced into the patient, find their way back to the bone marrow.

Which of the following statements describes the lysogenic cycle of lambda ( ) phage? A) After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. B) Most of the prophage genes are activated by the product of a particular prophage gene. C) The phage genome replicates along with the host genome. D) Certain environmental triggers can cause the phage to exit the host genome, switching from the lytic to the lysogenic. E) The phage DNA is incorporated by crossing over into any nonspecific site on the host cell s DNA.

C) The phage genome replicates along with the host genome.

A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur? A) The plants would develop some but not all of the symptoms of the TMV infection. B) The plants would develop symptoms typically produced by viroids. C) The plants would develop the typical symptoms of TMV infection. D) The plants would not show any disease symptoms. E) The plants would become infected, but the sap from these plants would be unable to infect other plants.

C) The plants would develop the typical symptoms of TMV infection.

Two closely related populations of mice have been separated for many generations by a river. Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a zone of overlap. Which of the following is not a possible outcome when they meet? A) They interbreed freely and produce fertile hybrid offspring. B) They no longer attempt to interbreed. C) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations. D) They remain separate in the extremes of their ranges but develop a persistent hybrid zone in the area of overlap. E) They interbreed in the region of overlap, but produce sterile offspring.

C) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations.

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) Natural selection cannot account for losses, only for innovations. 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) The ancestors of these organisms experienced harmful mutations that forced them to find new habitats that these species had not previously used.

C) Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.

Which describes the transfer of polypeptide sequences to a membrane to analyze gene expression? A) Southern blotting B) Northern blotting C) Western blotting D) Eastern blotting E) RT-PCR

C) Western blotting

The major advantage of using artificial chromosomes such as YACs and BACs for cloning genes is that A) plasmids are unable to replicate in cells. B) only one copy of a plasmid can be present in any given cell, whereas many copies of a YAC or BAC can coexist in a single cell. C) YACs and BACs can carry much larger DNA fragments than ordinary plasmids can. D) YACs and BACs can be used to express proteins encoded by inserted genes, but plasmids cannot. E) all of the above

C) YACs and BACs can carry much larger DNA fragments than ordinary plasmids can.

A student wishes to clone a sequence of DNA of ~200 kb. Which vector would be appropriate? A) a plasmid B) a typical bacteriophage C) a BAC D) a plant virus E) a large polypeptide

C) a BAC

According to the concept of punctuated equilibrium, A) natural selection is unimportant as a mechanism of evolution. B) given enough time, most existing species will branch gradually into new species. C) a new species accumulates most of its unique features as it comes into existence. D) evolution of new species features long periods during which changes are occurring, interspersed with short periods of equilibrium, or stasis. E) transitional fossils, intermediate between newer species and their parent species, should be abundant.

C) a new species accumulates most of its unique features as it comes into existence.

Which enzyme was used to produce the molecule in Figure 20.1? A) ligase B) transcriptase C) a restriction enzyme D) RNA polymerase E) DNA polymerase

C) a restriction enzyme

Plants are more readily manipulated by genetic engineering than are animals because A) plant genes do not contain introns. B) more vectors are available for transferring recombinant DNA into plant cells. C) a somatic plant cell can often give rise to a complete plant. D) genes can be inserted into plant cells by microinjection. E) plant cells have larger nuclei.

C) a somatic plant cell can often give rise to a complete plant.

Which of the following problems with animal cloning might result in premature death of the clones? A) use of pluripotent instead of totipotent stem cells B) use of nuclear DNA as well as mtDNA C) abnormal regulation due to variant methylation D) the indefinite replication of totipotent stem cells E) abnormal immune function due to bone marrow dysfunction

C) abnormal regulation due to variant methylation

A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. She tried decreasing the amount of methylation enzymes in the embryonic stem cells and then allowed the cells to further differentiate. Which of the following results would she most likely see? A) increased chromatin condensation B) decreased chromatin concentration C) abnormalities of mouse embryos D) decreased binding of transcription factors E) inactivation of the selected genes

C) abnormalities of mouse embryos

This binds to a site in the DNA far from the promoter to stimulate transcription: A) enhancer B) promoter C) activator D) repressor E) terminator

C) activator

DNA microarrays have made a huge impact on genomic studies because they A) can be used to eliminate the function of any gene in the genome. B) can be used to introduce entire genomes into bacterial cells. C) allow the expression of many or even all of the genes in the genome to be compared at once. D) allow physical maps of the genome to be assembled in a very short time. E) dramatically enhance the efficiency of restriction enzymes.

C) allow the expression of many or even all of the genes in the genome to be compared at once.

Altering patterns of gene expression in prokaryotes would most likely serve the organism s survival in which of the following ways? A) organizing gene expression so that genes are expressed in a given order B) allowing each gene to be expressed an equal number of times C) allowing the organism to adjust to changes in environmental conditions D) allowing young organisms to respond differently from more mature organisms E) allowing environmental changes to alter the prokaryote s genome

C) allowing the organism to adjust to changes in environmental conditions

When does exon shuffling occur? A) during splicing of DNA B) during mitotic recombination C) as an alternative splicing pattern in post-transcriptional processing D) as an alternative cleavage or modification post-translationally E) as the result of faulty DNA repair

C) as an alternative splicing pattern in post-transcriptional processing

The biological species concept is inadequate for grouping A) plants. B) parasites. C) asexual organisms. D) animals that migrate. E) sympatric populations.

C) asexual organisms.

A microarray known as a GeneChip, with most now known human protein coding sequences, has recently been developed to aid in the study of human cancer by first comparing two three subsets of cancer subtypes. What kind of information might be gleaned from this GeneChip to aid in cancer prevention? A) information about whether or not a patient has this type of cancer prior to treatment. B) evidence that might suggest how best to treat a person s cancer with chemotherapy. C) data that could alert patients to what kind of cancer they were likely to acquire. D) information about which parent might have provided a patient with cancer-causing genes. E) information on cancer epidemiology in the U.S. or elsewhere.

C) data that could alert patients to what kind of cancer they were likely to acquire.

The recessive allele that causes phenylketonuria (PKU) is harmful, except when an infants diet lacks the amino acid, phenylalanine. What maintains the presence of this harmful allele in a population s gene pool? A) heterozygote advantage B) stabilizing selection C) diploidy D) balancing selection

C) diploidy

Adult male humans generally have deeper voices than do adult female humans, as the direct result of higher levels of testosterone causing growth of the larynx. If one excludes the involvement of gender in the situation described in the paragraph above, then the pattern that is apparent in the fossil record is most similar to one that should be expected from A) pansexual selection. B) directional selection. C) disruptive selection. D) stabilizing selection. E) asexual selection.

C) disruptive selection.

These genes are expressed by the mother, and their products are deposited into the developing egg: A) homeotic genes B) segmentation genes C) egg-polarity genes D) morphogens E) inducers

C) egg-polarity genes

Two eukaryotic proteins have one domain in common but are otherwise very different. Which of the following processes is most likely to have contributed to this phenomenon? A) gene duplication B) RNA splicing C) exon shuffling D) histone modification E) random point mutations

C) exon shuffling

Bacteria containing recombinant plasmids are often identified by which process? A) examining the cells with an electron microscope B) using radioactive tracers to locate the plasmids C) exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid D) removing the DNA of all cells in a culture to see which cells have plasmids E) producing antibodies specific for each bacterium containing a recombinant plasmid

C) exposing the bacteria to an antibiotic that kills cells lacking the resistant plasmid

Restriction fragments of DNA are typically separated from one another by which process? A) filtering B) centrifugation C) gel electrophoresis D) PCR E) electron microscopy

C) gel electrophoresis

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 four of the original colonists died before they produced offspring, the ratios of genotypes could be quite different in the subsequent generations. This would be an example of A) diploidy. B) gene flow. C) genetic drift. D) disruptive selection. E) stabilizing selection.

C) genetic drift.

Which of the following characteristics, structures, or processes is common to both bacteria and viruses? A) metabolism B) ribosomes C) genetic material composed of nucleic acid D) cell division E) independent existence

C) genetic material composed of nucleic acid

The DNA polymerases of all cellular organisms have proofreading capability. This capability tends to reduce the introduction of A) extra genes by gene duplication events. B) chromosomal translocation. C) genetic variation by mutations. D) proofreading capability into prokaryotes.

C) genetic variation by mutations.

A defining characteristic of allopatric speciation is A) the appearance of new species in the midst of old ones. B) asexually reproducing populations. C) geographic isolation. D) artificial selection. E) large populations.

C) geographic isolation.

One species lives only in tree holes; another species lives only in streams. A) behavioral B) gametic C) habitat D) temporal E) mechanical

C) habitat

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island s lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. Using only the information provided in the paragraph, which of these is the best initial hypothesis for how D. santomea descended from D. yakuba? A) geographic isolation B) autopolyploidy C) habitat differentiation D) sexual selection E) allopolyploidy

C) habitat differentiation

If you were to observe the activity of methylated DNA, you would expect it to A) be replicating nearly continuously. B) be unwinding in preparation for protein synthesis. C) have turned off or slowed down the process of transcription. D) be very actively transcribed and translated. E) induce protein synthesis by not allowing repressors to bind to it.

C) have turned off or slowed down the process of transcription.

Theoretically, the production of sterile mules by interbreeding between female horses and male donkeys should A) result in the extinction of one of the two parental species. B) cause convergent evolution. C) strengthen postzygotic barriers between horses and donkeys. D) weaken the intrinsic reproductive barriers between horses and donkeys. E) eventually result in the formation of a single species from the two parental species

C) strengthen postzygotic barriers between horses and donkeys.

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island s lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. Which of these reduces gene flow between the gene pools of the two species on Sao Tomé, despite the existence of hybrids? A) hybrid breakdown B) hybrid inviability C) hybrid sterility D) temporal isolation E) a geographic barrier

C) hybrid sterility

Which of the following techniques used to analyze gene function depends on the specificity of DNA base complementarity? A) Northern blotting B) use of RNAi C) in vitro mutagenesis D) in situ hybridization E) restriction fragment analysis

C) in vitro mutagenesis

Which of the following procedures would produce RFLPs? A) incubating a mixture of single-stranded DNA from two closely related species B) incubating DNA nucleotides with DNA polymerase C) incubating DNA with restriction enzymes D) incubating RNA with DNA nucleotides and reverse transcriptase E) incubating DNA fragments with sticky ends with ligase

C) incubating DNA with restriction enzymes

DNA technology has many medical applications. Which of the following is not done routinely at present? A) production of hormones for treating diabetes and dwarfism B) production of viral proteins for vaccines C) introduction of genetically engineered genes into human gametes D) prenatal identification of genetic disease genes E) genetic testing for carriers of harmful alleles

C) introduction of genetically engineered genes into human gametes

During DNA replication, A) all methylation of the DNA is lost at the first round of replication. B) DNA polymerase is blocked by methyl groups, and methylated regions of the genome are therefore left uncopied. C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication. D) methylation of the DNA is maintained because DNA polymerase directly incorporates methylated nucleotides into the new strand opposite any methylated nucleotides in the template. E) methylated DNA is copied in the cytoplasm, and unmethylated DNA in the nucleus.

C) methylation of the DNA is maintained because methylation enzymes act at DNA sites where one strand is already methylated and thus correctly methylates daughter strands after replication.

In Darwin s thinking, the more closely related two different organisms are, the A) more similar their habitats are. B) less similar their DNA sequences are. C) more recently they shared a common ancestor. D) less likely they are to have the same genes in common. E) more similar they are in size.

C) more recently they shared a common ancestor.

According to the punctuated equilibria model, A) natural selection is unimportant as a mechanism of evolution. B) given enough time, most existing species will branch gradually into new species. C) most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species. D) most evolution occurs in sympatric populations. E) speciation is usually due to a single mutation.

C) most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.

Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene A) is transcribed in the early embryo. B) normally leads to formation of tail structures. C) normally leads to formation of head structures. D) is a protein present in all head structures. E) leads to programmed cell death.

C) normally leads to formation of head structures.

Upon undergoing change, which of these genes is most likely to result in speciation while a geographic barrier separates two populations of a flowering-plant species? A) one that affects the rate of chlorophyll a synthesis B) one that affects the amount of growth hormone synthesized per unit time C) one that affects the compatibility of male pollen and female reproductive parts D) one that affects the average depth to which roots grow down through the soil E) one that affects how flexible the stems are

C) one that affects the compatibility of male pollen and female reproductive parts

Gene flow is a concept best used to describe an exchange between A) species. B) males and females. C) populations. D) individuals. E) chromosomes.

C) populations.

Which of the following terms describes bacteriophage DNA that has become integrated into the host cell chromosome? A) intemperate bacteriophages B) transposons C) prophages D) T-even phages E) plasmids

C) prophages

A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using A) RNA polymerase to transcribe the gene. B) a restriction enzyme to cut the gene into shorter pieces. C) reverse transcriptase to reconstruct the gene from its mRNA. D) DNA polymerase to reconstruct the gene from its polypeptide product. E) DNA ligase to put together fragments of the DNA that codes for a particular polypeptide.

C) reverse transcriptase to reconstruct the gene from its mRNA.

Male satin bowerbirds adorn structures that they build, called bowers, with parrot feathers, flowers, and other bizarre ornaments in order to attract females. Females inspect the bowers and, if suitably impressed, allow males to mate with them. The evolution of this male behavior is due to A) frequency-dependent selection. B) artificial selection. C) sexual selection. D) natural selection. E) disruptive selection.

C) sexual selection.

The average birth weight for human babies is about 3 kg. Which of the following terms best describes this? A) artificial selection B) directional selection C) stabilizing selection D) disruptive selection E) sexual selection

C) stabilizing selection

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 percentage of the population that is heterozygous for this allele? A) 90 B) 81 C) 49 D) 18 E) 10

D) 18

Among known plant species, which of these have been the two most commonly occurring phenomena leading to the origin of new species? 1. allopatric speciation 2. sympatric speciation 3. sexual selection 4. polyploidy A) 1 and 3 B) 1 and 4 C) 2 and 3 D) 2 and 4

D) 2 and 4

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be A) 12. B) 14. C) 16. D) 28. E) 56.

D) 28.

Cattle breeders have improved the quality of meat over the years by which process? A) artificial selection B) directional selection C) stabilizing selection D) A and B

D) A and B

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 identifying the bones as being homologous B) By the principle of convergent evolution C) By proposing that humans, bats, and dolphins share a common ancestor D) A and C only E) A, B, and C

D) A and C only

Within a few weeks of treatment with the drug 3TC, a patient s HIV population consists entirely of 3TC-resistant viruses. How can this result best be explained? A) HIV can change its surface proteins and resist vaccines. B) The patient must have become reinfected with 3TC-resistant viruses. C) HIV began making drug-resistant versions of reverse transcriptase in response to the drug. D) A few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency. E) The drug caused the HIV RNA to change.

D) A few drug-resistant viruses were present at the start of treatment, and natural selection increased their frequency.

Which of the following is characteristic of the lytic cycle? A) Many bacterial cells containing viral DNA are produced. B) Viral DNA is incorporated into the host genome. C) The viral genome replicates without destroying the host. D) A large number of phages is released at a time. E) The virus-host relationship usually lasts for generations.

D) A large number of phages is released at a time.

At the beginning of this century there was a general announcement regarding the sequencing of the human genome and the genomes of many other multicellular eukaryotes. There was surprise expressed by many that the number of protein-coding sequences is much smaller than they had expected. Which of the following accounts for most of the rest? A) junk DNA that serves no possible purpose B) rRNA and tRNA coding sequences C) DNA that is translated directly without being transcribed D) non-protein coding DNA that is transcribed into several kinds of small RNAs with biological function E) non-protein coding DNA that is transcribed into several kinds of small RNAs without biological function

D) non-protein coding DNA that is transcribed into several kinds of small RNAs with biological function

Transcription factors in eukaryotes usually have DNA binding domains as well as other domains also specific for binding. In general, which of the following would you expect many of them to be able to bind? A) repressors B) ATP C) protein-based hormones D) other transcription factors E) tRNA

D) other transcription factors

A rapid method of speciation that has been important in the history of flowering plants is A) genetic drift. B) a mutation in the gene controlling the timing of flowering. C) behavioral isolation. D) polyploidy.

D) polyploidy.

If neutral variation is truly neutral, then it should have no effect on A) nucleotide diversity. B) average heterozygosity. C) our ability to measure the rate of evolution. D) relative fitness. E) gene diversity.

D) relative fitness.

This can inhibit transcription by blocking the binding of positively acting transcription factors to the DNA: A) enhancer B) promoter C) activator D) repressor E) terminator

D) repressor

What characteristics of electron microscopes make them most useful for studying viruses? A) high energy electrons with high penetrance B) requirement that specimens be viewed in a vacuum C) necessity for specimens to be dry and fixed D) shorter wavelengths providing higher resolution E) use of magnetic fields to focus electrons

D) shorter wavelengths providing higher resolution

Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome? A) size of the viral capsomeres B) RNA versus DNA genome C) double versus single strand genomes D) size and shape of the capsid E) glycoproteins of the envelope

D) size and shape of the capsid

According to the concept of punctuated equilibrium, the sudden appearance of a new species in the fossil record means that A) the species is now extinct. B) speciation occurred instantaneously. C) speciation occurred in one generation. D) speciation occurred rapidly in geologic time. E) the species will consequently have a relatively short existence, compared with other species.

D) speciation occurred rapidly in geologic time.

One species mates at the season when daylight is increasing from 13 hours to 13 hours, 15 minutes; another species mates at the season when daylight is increasing from 14 hours to 14 hours, 15 minutes. A) behavioral B) gametic C) habitat D) temporal E) mechanical

D) temporal

The lactose operon is likely to be transcribed when A) there is more glucose in the cell than lactose. B) the cyclic AMP levels are low. C) there is glucose but no lactose in the cell. D) the cyclic AMP and lactose levels are both high within the cell. E) the cAMP level is high and the lactose level is low.

D) the cyclic AMP and lactose levels are both high within the cell.

The incidence of cancer increases dramatically in older humans because A) the Ras protein is more likely to be hyperactive after age sixty. B) proteasomes become more active with age. C) as we age, normal cell division inhibitors cease to function. D) the longer we live, the more mutations we accumulate. E) tumor-suppressor genes are no longer able to repair damaged DNA.

D) the longer we live, the more mutations we accumulate.

About which of these did Darwin have a poor understanding? A) that individuals in a population exhibit a good deal of variation B) that much of the variation between individuals in a population is inherited C) the factors that cause individuals in populations to struggle for survival D) the sources of genetic variations among individuals E) how a beneficial trait becomes more common in a population over the course of generations

D) the sources of genetic variations among individuals

Why are yeast cells frequently used as hosts for cloning? A) they easily form colonies B) they can remove exons from mRNA. C) they do not have plasmids. D) they are eukaryotic cells E) only yeast cells allow the gene to be cloned

D) they are eukaryotic cells

What is the enzymatic function of restriction enzymes? A) to add new nucleotides to the growing strand of DNA B) to join nucleotides during replication C) to join nucleotides during transcription D) to cleave nucleic acids at specific sites E) to repair breaks in sugar-phosphate backbones

D) to cleave nucleic acids at specific sites

Fragments of DNA have been extracted from the remnants of extinct wooly mammoths, amplified, and sequenced. These can now be used to A) introduce into relatives, such as elephants, certain mammoth traits. B) clone live wooly mammoths. C) study the relationships among wooly mammoths and other wool-producers. D) understand the evolutionary relationships among members of related taxa. E) appreciate the reasons why mammoths went extinct

D) understand the evolutionary relationships among members of related taxa.

In a hypothetical population of 1,000 people, tests of blood-type genes show that 160 have the genotype AA, 480 have the genotype AB, and 360 have the genotype BB. 33) What is the frequency of the B allele? A) 0.001 B) 0.002 C) 0.100 D) 0.400 E) 0.600

E) 0.600

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) 0.60 C) 0.64 D) 0.75 E) 0.80

E) 0.80

In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In rangelands of the western United States, pronghorns and cattle often associate with one another. If some of these fleas develop a strong preference, instead, for cattle blood and mate only with fleas that, likewise, prefer cattle blood, then over time which of these should occur, if the host mammal can be considered as the fleas habitat? 1. reproductive isolation 2. sympatric speciation 3. habitat isolation 4. prezygotic barriers A) 1 only B) 2 and 3 C) 1, 2, and 3 D) 2, 3, and 4 E) 1 through 4

E) 1 through 4

Approximately what proportion of the DNA in the human genome codes for proteins or functional RNA? A) 83% B) 46% C) 32% D) 13% E) 1.5%

E) 1.5%

To observe natural selection s effects on a population, which of these must be true? A) One must observe more than one generation of the population. B) The population must contain genetic variation. C) Members of the population must increase or decrease the use of some portion of their anatomy. D) A and C only E) A and B only

E) A and B only

The higher the proportion of loci that are fixed in a population, the lower is that population s A) nucleotide variability. B) genetic polyploidy. C) average heterozygosity. D) A, B, and C E) A and C only

E) A and C only

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 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 number of predators may have decreased. C) The squirrels of subsequent generations should show greater levels of genetic variation than previous generations, because squirrels that would not have survived in the past will now survive. D) A and B only E) A, B, and C

E) A, B, and C

If the frequency of a particular allele that is present in a small, isolated population of alpine plants decreases due to a landslide that leaves an even smaller remnant of surviving plants bearing this allele, then what has occurred? A) a bottleneck B) genetic drift C) microevolution D) A and B only E) A, B, and C

E) A, B, and C

In order to identify a specific restriction fragment using a probe, what must be done? A) The fragments must be separated by electrophoresis. B) The fragments must be treated with heat or chemicals to separate the strands of the double helix. C) The probe must be hybridized with the fragment. D) Only A and B are correct. E) A, B, and C are correct.

E) A, B, and C are correct.

Which of the following series best reflects what we know about how the flu virus moves between species? A) An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans. B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. C) A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. D) An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. E) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.

E) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.

In order for speciation to occur, what is true? A) The number of chromosomes in the genome must change. B) Changes to centromere location or chromosome size must occur within the genome. C) Large numbers of genes that affect a single phenotypic trait must change. D) Large numbers of genes that affect numerous phenotypic traits must change. E) At least one gene, affecting at least one phenotypic trait, must change.

E) At least one gene, affecting at least one phenotypic trait, must change.

Ichthyosaurs were aquatic dinosaurs. 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) homologous. B) examples of convergent evolution. C) adaptations to a common environment. D) A and C only E) B and C only

E) B and C only

In a hypothetical population s gene pool, an autosomal gene, which had previously been fixed, undergoes a mutation that introduces a new allele, one inherited according to incomplete dominance. Natural selection then causes stabilizing selection at this locus. Consequently, what should happen over the course of many generations? A) The proportions of both types of homozygote should decrease. B) The proportion of the population that is heterozygous at this locus should remain constant. C) The population s average heterozygosity should increase. D) Both (A)and (B) E) Both (A)and (C)

E) Both (A)and (C)

Since Watson and Crick described DNA in 1953, which of the following might best explain why the function of small RNAs is still being explained? A) As RNAs have evolved since that time, they have taken on new functions. B) Watson and Crick described DNA but did not predict any function for RNA. C) The functions of small RNAs could not be approached until the entire human genome was sequenced. D) Ethical considerations prevented scientists from exploring this material until recently. E) Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible.

E) Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible.

Of the following anatomical structures, which is homologous to the wing of a bird? A) Dorsal fin of a shark B) Hindlimb of a kangaroo C) Wing of a butterfly D) Tail fin of a flying fish E) Flipper of a cetacean

E) Flipper of a cetacean

Which of the following factors would not contribute to allopatric speciation? A) A population becomes geographically isolated from the parent population. B) The separated population is small, and genetic drift occurs. C) The isolated population is exposed to different selection pressures than the ancestral population. D) Different mutations begin to distinguish the gene pools of the separated populations. E) Gene flow between the two populations is extensive.

E) Gene flow between the two populations is extensive.

Which of the following has the largest genome and the fewest genes per million base pairs? A) Haemophilus influenzae (bacterium) B) Saccharomyces cerevisiae (yeast) C) Arabidopsis thaliana (plant) D) Drosophila melanogaster (fruit fly) E) Homo sapiens (human)

E) Homo sapiens (human)

Which of the following statements best summarizes evolution as it is viewed today? A) It is goal-directed. B) It represents the result of selection for acquired characteristics. C) It is synonymous with the process of gene flow. D) It is the descent of humans from the present-day great apes. E) It is the differential survival and reproduction of the most-fit phenotypes.

E) It is the differential survival and reproduction of the most-fit phenotypes.

Which of the following statements about the DNA in one of your brain cells is true? A) Most of the DNA codes for protein. B) The majority of genes are likely to be transcribed. C) Each gene lies immediately adjacent to an enhancer. D) Many genes are grouped into operon-like clusters. E) It is the same as the DNA in one of your heart cells.

E) It is the same as the DNA in one of your heart cells.

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. That the actual forelimbs of these mammals do not seem to be optimally arranged is because A) natural selection has not had sufficient time to create the optimal design in each case, but will do so given enough time. B) natural selection operates in ways that are beyond the capability of the human mind to comprehend. C) in many cases, phenotype is not merely determined by genotype, but by the environment as well. D) though we may not consider the fit between the current skeletal arrangements and their functions excellent, we should not doubt that natural selection ultimately produces the best design. E) natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

E) natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

Which of the following is most closely identical to the formation of twins? A) cell cloning B) therapeutic cloning C) use of adult stem cells D) embryo transfer E) organismal cloning

E) organismal cloning

Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development? A) morphogenesis B) determination C) induction D) differentiation E) pattern formation

E) pattern formation

Which example below will most likely guarantee that two closely related species will persist only as distinct biological species? A) colonization of new habitats B) convergent evolution C) hybridization D) geographic isolation from one another E) reproductive isolation from one another

E) reproductive isolation from one another

Which of the following is used to make complementary DNA (cDNA) from RNA? A) restriction enzymes B) gene cloning C) DNA ligase D) gel electrophoresis E) reverse transcriptase

E) reverse transcriptase

What is it that can be duplicated in a genome? A) DNA sequences above a minimum size only B) DNA sequences below a minimal size only C) entire chromosomes only D) entire sets of chromosomes only E) sequences, chromosomes, or sets of chromosomes

E) sequences, chromosomes, or sets of chromosomes

Which describes brightly colored peacocks mating more frequently than drab peacocks? A) artificial selection B) directional selection C) stabilizing selection D) disruptive selection E) sexual selection

E) sexual selection

Most Swiss starlings produce four to five eggs in each clutch. Those producing fewer or more than this have reduced fitness. Which of the following terms best describes this? A) artificial selection B) directional selection C) stabilizing selection D) disruptive selection E) sexual selection

E) stabilizing selection

This is the site in the DNA located near the end of the final exon, encoding an RNA sequence that determines the 3 end of the transcript: A) enhancer B) promoter C) activator D) repressor E) terminator

E) terminator

The role of a metabolite that controls a repressible operon is to: A. bind to the promoter region and decreases the affinity of RNA polymerase for the promoter B. Bind to the operator region and block the attachment of RNA polymerase to the promoter C. increase the production of inactive repressor proteins D. bind to the repressor protein and inactivate it E. bind to the repressor protein and activate it

E. Bind to the repressor protein and activate it

A lack of this nonprotein molecule would result in the inability of the cell to turn off genes: A) operon B) inducer C) promoter D) repressor E) corepressor

E. Corepressor

The tryptophan operon is a repressible operon that is A. permanently turned on B. turned on only when tryptophan is present in the growth medium C. turned off only when glucose is present in the growth medium D. turned on only when glucose is present in the growth medium E. turned off whenever tryptophan is added to the growth medium

E. Turned off whenever tryptophan is added to the growth medium

This protein is produced by a regulatory gene A. operon B. inducer C. promoter D. repressor E. corepressor

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