Which of the following molecules is most involved in the transfer of genetic information from the nucleus to the cytoplasm?
A) DNA
B) mRNA
C) tRNA D) Proteins E) Lipids
Ans: B
If a trait that is not expressed in the F1 generation reappears in the F2 generation, the inheritance of the trait in question is an example of
A) codominance.
B) dominance and recessiveness.
C) incomplete dominance. D) epistasis.
E) a test cross.
B
A strand of DNA with the sequence 5′-ATTCCG-3′ would have a complementary strand with the sequence
A) 5′-TAAGGC-3′. B) 5′-ATTCCG-3′. C) 5′-ACCTTA-3′. D) 5′-CGGAAT-3′. E) 5′-GCCTTA-3′.
D
Single base changes in the coding regions of proteins can cause _______ mutations. A) missense
B) nonsense
C) frame-shift
D) silent
E) All of the above
E
Which of the following molecules functions to transfer information from one generation to the next in eukaryotes?
A) DNA
B) mRNA
C) tRNA D) Proteins E) Lipids
A
Which of the following changes affects more than a single amino acid in a sequence? A) A silent mutation
B) A missense mutation
C) A frameshift mutation
D) Both a and b E) Both b and c
C
Mendel concluded that each pea has two units for each character,and each gamete contains one unit. Mendel's "unit" is now referred to as a(n)
A) gene.
B) character.
C) locus.
D) transcription factor. E) None of the above
A
Which of the following molecules are contained in a spliceosome? A) DNA and RNA
B) DNA and protein
C) RNA and protein
D) RNA and lipid E) Protein and lipid
C
If a 5′-to-3′ strand of DNA has the sequence GTCTATGCATTA, what is the template DNA strand that would be used for transcription?
A) 5′-GTCTATGCATTA-3′
B) 5′-CAGATACGTAAT-3′
C) 3′-GTCTATGCATTA-5′ D) 3′-CAGATACGTAAT-5′ E) 5′-GUCUAUGCAUUA-3′
D
When cyclin binds Cdk,
A) the cell transitions from G2 to S. B) kinase activation occurs.
C) chromosomes condense.
D) the cell quickly enters M phase. E) the cell undergoes apoptosis.
B
Asexual reproduction produces genetically identical individuals because A) chromosomes do not have to replicate during asexual reproduction. B) it involves chromosome replication without cytokinesis.
C) no meiosis or fertilization takes place.
D) cell division occurs only in meiosis.
E) the mitotic spindle prevents nondisjunction. Ans: C
C
A deoxyribonucleoside is a
A) deoxyribose plus a nitrogenous base.
B) sugar and a phosphate.
C) deoxyribose plus a nitrogenous base and a phosphate.
D) ribose plus a nitrogenous base.
E) nitrogenous base bonded at the 5′ end to a sugar-phosphate backbone.
C
Different forms of a gene are called A) traits.
B) phenotypes.
C) genotypes.
D) alleles.
E) None of the above
D
If two strains of true-breeding plants that have different alleles for a certain character are crossed, their progeny are called
A) the P generation.
B) the F1 generation.
C) the F2 generation. D) F1 crosses.
E) F2 progeny.
B
The enzyme that restores the phosphodiester linkage between adjacent fragments in the lagging strand during DNA replication is
A) primase.
B) reverse transcriptase.
C) DNA ligase.
D) helicase.
E) DNA polymerase I.
C
In all sexually reproducing organisms, the diploid phase of the life cycle begins at A) spore formation.
B) gamete formation.
C) meiosis.
D) mitosis.
E) fertilization.
E
The strands that make up DNA are antiparallel.This means that
A) one strand is positively charged, and the other is negatively charged.
B) the base pairings create unequal spacing between the two DNA strands.
C) the 5′-to-3′ direction of one strand is counter to the 5′-to-3′ direction of the other strand. D) the twisting of the DNA molecule has shifted the two strands.
E) purines bond with purines and pyrimidines bond with pyrimidines.
C
During replication,the new DNA strand is synthesized
A) in the 3′-to-5′ direction.
B) in the 5′-to-3′ direction.
C) in both the 3′-to-5′ and 5′-to-3′ directions from the replication fork. D) from one end to the other, in the 3′-to-5′ or the 5′-to-3′ direction. E) None of the above
B
Interphase involves all of the following except
A) DNA replication.
B) the synthesis of cellular components necessary for mitosis. C) G1
D) the condensation of chromatin.
E) G2
D
Microtubules that form the mitotic spindle tend to originate from or terminate in A) centromeres and telomeres.
B) euchromatin.
C) centrioles and telomeres.
D) the nuclear envelope.
E) centrioles and kinetochores.
E
The most important thing a living cell does is:
A) Produce enough protein to undergo cell division B) Avoid the ionizing effect of radiation
C) Transcribe all genes effectively all the time
D) Replicate its DNA with high fidelity
E) Eliminate intervening sequences in RNA
D
Why did the original "one-gene, one-enzyme" hypothesis have to be modified? A) Some RNAs have catalytic activity.
B) Not all proteins are coded by genes.
C) Some enzymes are made up of more than one polypeptide.
D) All genes code for multiple enzymes. E) Not all enzymes are coded for by genes.
C
A pea plant with red flowers is test crossed, and one-half of the resulting progeny have red flowers, while the other half has white flowers. Therefore, the genotype of the test-crossed parent was
A) RR.
B) Rr.
C) rr.
D) either RR or Rr.
E) This cannot be answered without more information.
B
How does a nucleus in G2 differ from a nucleus in G1?
A) The G2 nucleus has twice the amount of DNA as the G1 nucleus. B) DNA synthesis occurs only in G1 phase.
C) Inactive cells are arrested only in G2 phase.
D) During G2, the cell prepares for S phase.
E) All of the above
A
In a(n) _______ cross, genes for two different characters separate. A) monohybrid
B) dihybrid
C) trihybrid
D) F1 E) F2
B
The DNA of a eukaryotic cell is A) double-stranded.
B) single-stranded.
C) circular.
D) complex inverted. E) conservative.
A
The transcription initiation site is located A) within the promoter.
B) on RNA polymerase.
C) at splice sites.
D) in a ribosome.
E) None of the above
A
In an organism with a diploid number of 8, a gamete has _______ chromosomes, a liver cell has _______ chromosomes, and a sperm cell at meiotic anaphase I has _______ chromosomes.
A) 8; 8; 8
B) 8; 4; 8
C) 8; 4; 4 D) 4; 8; 8 E) 4; 4; 4
D
The energy to move chromosomes during mitosis is provided by A) centrioles.
B) DNA polymerization.
C) migration of the centrosomes. D) formation of the cell plate.
E) ATP.
E
The process by which information in the nucleic acid sequence is used to direct the production of a specific chain of amino acids is called
A) initiation.
B) hybridization.
C) transcription.
D) translation.
E) None of the above
D
Separation of the alleles of a single gene into different gametes is called A) synapsis.
B) segregation.
C) independent assortment. D) heterozygous separation. E) recombination.
B
Chargaff's rule states that
A) DNA must be replicated before a cell can divide.
B) viruses enter cells without their protein coat.
C) only protein from the infecting phage can also be detected in progeny phage. D) only nucleic acids enter the cell during infection.
E) the amount of cytosine equals the amount of guanine.
E
Refer to the following diagram of DNA complementary base pairing. Which of the following bases would pair (from top to bottom) with the exposed 3′-end strand?
A) GACT
B) TCGA
C) AGCT
D) TAGC
E) ATCG
B
Termination of transcription involves a A) stop codon.
B) terminator sequence.
C) termiproteator.
D) hairline slip. E) series of As.
B
The mitotic spindle is composed of A) chromosomes.
B) chromatids.
C) microtubules.
D) chromatin. E) centrosomes.
C
Meiosis can occur
A) in all sexually reproducing organisms. B) only when an organism is diploid.
C) only in multicellular organisms.
D) only in haploid organisms.
E) only in single-celled organisms.
A
DNAreplicationoccurs
A) during both mitosis and meiosis. B) only during mitosis.
C) only during meiosis.
D) during S phase.
E) Both A and D
E
Mendel's crossing of spherical-seeded pea plants with wrinkled-seeded pea plants resulted in progeny that all had spherical seeds. This indicates that the wrinkled-seed trait is
A) codominant.
B) dominant.
C) recessive. D) Both a and b E) Both a and c
C
Termination of translation requires
A) a termination signal, RNA polymerase, and a release factor.
B) a release factor, initiator tRNA, and ribosomes.
C) initiation factors, the small subunit of the ribosome, and mRNA.
D) elongation factors and charged tRNAs.
E) a stop codon positioned at the A site of the ribosome, peptidyl transferase, and a release
factor.
E
Which of the following statements about the flow of genetic information is true?
A) Proteins encode information that is used to produce other proteins of the same amino acid
sequence.
B) RNA encodes information that is translated into DNA, and DNA encodes information
that is translated into proteins.
C) Proteins encode information that can be transcribed into RNA, and RNA encodes
information that can be transcribed into DNA.
D) DNA encodes information that is transcribed into RNA, and RNA encodes information
that is translated into proteins.
E) None of the above
D
Transcription is the process by which
A) a DNA molecule is synthesized from an RNA template.
B) ribonucleoside triphosphates are assembled into an RNA molecule without a template. C) an RNA molecule is synthesized from a DNA template.
D) a protein is synthesized with information from a messenger RNA.
E) a single-stranded DNA molecule is replicated.
C
Semiconservative replication of DNA involves
A) each of the original strands acting as a template for a new strand.
B) only one of the original strands acting as a template for a new strand.
C) the complete separation of the original strands, the synthesis of new strands, and the
reassembly of double-stranded molecules.
D) the use of the intact double-stranded molecule as a template. E) None of the above
A
The microtubules of the mitotic spindle attach to a specialized structure in the centromere region of each chromosome called the
A) kinetochore.
B) nucleosome.
C) equatorial plate. D) aster.
E) centrosome.
A
Why is RNA incorporated into the DNA molecule during DNA replication? A) RNA primase adds bases that act as primers.
B) RNA primase is able to use DNA as a template.
C) RNA primase must be incorporated into the holoenzyme complex. D) DNA polymerases can only add on to an existing strand.
E) All of the above
D
A mutant strain of yeast grew well at 20°C, but not at 37°C, whereas the wild-type strain grew well at both temperatures. The mutation is an example of a
A) conditional mutation.
B) missense mutation.
C) point mutation.
D) frame-shift mutation.
E) gain-of-function mutation.
A
The genotype of an organism that expresses a dominant trait can be determined by A) crossing the organism with a homozygous dominant organism.
B) crossing the organism with a heterozygous dominant organism.
C) crossing the organism with a homozygous recessive organism.
D) observing the phenotype of the progeny from any cross. E) observing the genotype of the progeny from any cross.
C
Craig Venter, a leader of one of the teams that sequenced the human genome, has now turned his attention to cataloging the microbial life of the oceans. His studies, which involve PCR amplification of microbial DNA and a sequencing of the PCR products, are part of a field of biology called
A) functional genomics. B) transposon-tagging. C) proteomics.
D) phenomics.
E) metagenomics.
E
Which of the following techniques or tools is best suited to determine the minimal genome of a free-living bacterium?
A) Metagenomics
B) Haplotype mapping
C) Pharmacogenetics
D) Bacterial artificial chromosomes E) Selective inactivation of genes
E
Which of the following statements about Hox genes is false?
A) They contain homeoboxes.
B) They were derived from duplications of a single ancestral gene.
C) They encode transcription factors.
D) They are found only in Drosophila and a few closely related genera of flies. E) All of the above are true; none is false.
D
Which of the following would provide the best evidence for genomic equivalence? A) Observations of determination in an undifferentiated cell
B) Demonstration of totipotency from a somatic cell
C) Evidence that environmental signals cause differentiation in stem cells
D) Observations of polarity in an early embryo
E) Microarray studies showing changes in gene expression
B
Sequencing of the human genome has allowed scientists to
A) understand regulatory sequences that are important for gene expression.
B) locate genes that cause disease.
C) understand evolutionary relationships by comparing human genes to genes in other
organisms.
D) investigate gene families and their origins. E) All of the above
E
A biologist who is trying to find open reading frames in a section of DNA is working in the field of
A) functional genomics. B) comparative genomics. C) metagenomics.
D) biodiversity.
E) proteomics.
A
Which of the following is not a potential point of regulation of gene expression? A) The level of transcription
B) The level of processing mRNA
C) The level of mRNA stability
D) The level of translation
E) All of the above are potential points of gene regulation.
E
Which of the following is an example of heterochrony?
A) A gene whose expression causes legs to form
B) A gene whose expression inhibits the formation of legs
C) A gene whose expression causes one segment to start growing sooner than it would
in the absence of that gene
D) A gene whose expression affects more than one module E) None of the above
C
In the absence of substance M, a hypothetical LM operon is turned off. If substance M is abundant, it can bind to the repressor, which permits the polymerase to begin transcribing the DNA. In this case, LM is a(n) _______ operon and M acts as a(n) _______.
A) repressible; inducer
B) repressible, transcription factor C) inducible; inducer
D) inducible; co-repressor
E) inducible; transcription factor
C
Which of the following statements about eukaryotic genomes is false?
A) They tend to be larger than prokaryotic genomes.
B) They tend to have more regulatory sequences than prokaryotic genomes have. C) The percentage of the genome devoted to coding sequence is higher than in
prokaryotic genomes.
D) They usually have more repetitive DNA than prokaryotic genomes have. E) All of the above are true; none is false.
C
DNA sequencing is most like the natural process of A) protein synthesis.
B) DNA repair.
C) DNA replication.
D) reverse transcription. E) alternative splicing.
C
Comparative genomics
A) assigns functions to the products of genes.
B) assigns functions to regulatory sequences.
C) compares genes in different organisms to see how those organisms are related
physiologically. D) Both a and c
E) All of the above
C
Two-dimensional gel electrophoresis separates proteins based on _______ and _______. A) size; concentration
B) size; shape
C) size; charge
D) concentration; shape E) shape; charge
C
Which of the following genomes is most likely that of a free-living prokaryote?
A) A genome that is 300 million bp long with over 50 percent repetitive DNA and
many introns
B) A genome that is 16,000 bp long and arranged in a circle
C) A genome that is 3 million bp long, arranged in a single circular chromosome, and
has little repetitive DNA
D) A genome that is 3 million bp long, is arranged in many linear chromosomes, and
has many introns
E) None of the above
C
Which of the following statements about prokaryotes is true?
A) They generally live in static environments.
B) The most efficient means of regulation of gene expression in these organisms is
usually at the level of transcription.
C) By making certain proteins only when needed, they save energy and other
resources. D) Both a and b E) Both b and c
E
In eukaryotes, a promoter is the region of
A) a plasmid that binds the enzymes for replication. B) the mRNA that binds to a ribosome.
C) DNA that binds RNA polymerase.
D) the mRNA that binds tRNAs.
E) None of the above
C
Bacteria protect themselves from their own restriction enzymes by A) means of their blunt ends.
B) means of their sticky ends.
C) adding methyl groups at restriction sites.
D) means of DNA ligase.
E) transforming themselves
C
Which enzyme is required to bring lactose into E. coli cells? A) β-galactoside permease
B) β-galactoside transferase
C) β-galactoside transacetylase
D) β-galactosidase E) None of the above
A
If the anchor cell is destroyed in Caenorhabditis elegans,
A) no vulva will form.
B) no anchorettes will form.
C) secondary vulval precursors will become primary vulval cells. D) another cell will differentiate into an anchor cell.
E) signals from the nematode's surface will direct readjustments.
A
An engineered DNA molecule that contains sequences from cattle and sequences from bacteria would be considered to be _______ DNA.
A) transgenic
B) recombinant
C) electroporated
D) genomic
E) None of the above
B
In negative regulation,
A) the gene is never transcribed.
B) the gene is always transcribed.
C) binding of an activator stimulates transcription.
D) transcription can be turned off when a repressor binds to the DNA near the
promoter.
E) a transcription factor is required in order for the gene to be transcribed.
D
Different results are achieved when an eight-cell sea urchin embryo is bisected horizontally as opposed to when it is bisected vertically. This observation supports which of the following statements?
A) Cellular determinants are equally distributed in the embryo.
B) Differentiation has occurred by the eight-cell stage.
C) Inducers have determined cell fate by the eight-cell stage. D) Polarity exists in the embryo by the eight-cell stage.
E) None of the above
D
In the context of metabolomics, glucose would be considered a A) haplotype.
B) primary metabolite. C) secondary metabolite. D) tertiary metabolite. E) None of the above
B
Haplotype maps are based primarily on
A) positions of transposons.
B) variations at specific nucleotides.
C) whether or not open reading frames exist. D) the extent to which a gene is expressed. E) None of the above
B
Which of the following statements about the evolution of development is false?
A) Evolution by natural selection "works" like a tinker, assembling new structures by
combining and modifying available materials.
B) Nearly all evolutionary innovations are the result of modifications of previously
existing mechanisms and structures.
C) The genes that control development are highly conserved.
D) Natural selection can act on any signaling pathway that affects development.
E) All of the above are true; none is false
E
Without maintenance methylase, the changes made by DNA methylase would not A) be able to decrease transcription of a gene.
B) be able to increase transcription of a gene.
C) be passed on from one generation to the next.
D) coordinate regulation across different genes. E) produce microRNA.
C
Nucleosomes disaggregate to allow transcription and then reaggregate A) through alternative splicing.
B) by acetylation and deacetylation.
C) through alternation of nucleotides.
D) through attachment of ubiquitin. E) through insertion of nucleotides.
B
Which of the following is required for the formation of gene families? A) Highly repetitive DNA
B) Pseudogenes
C) Transposable elements
D) Regulatory sequences E) Gene duplication
E
Which of the following statements about viruses is true?
A) They are not cells.
B) They can regulate the movements of substances into and out of the cell. C) They can reproduce outside living cells.
D) They are large and therefore easy to study.
E) None of the above
A
What type of molecule is a transcription factor? A) Protein
B) Enzyme
C) DNA
D) Carbohydrate E) Both a and b
A
Some metabolic pathways are regulated in part by changes in the rate of degradation of key enzymes. This is an example of
A) operon control.
B) transcriptional control.
C) liquid hybridization.
D) feedback inhibition.
E) posttranslational control.
E
DNA is cut at specific sites by means of A) DNA ligases.
B) transposons.
C) restriction enzymes.
D) DNA slicases.
E) DNA methylases.
C
Which of the following represents the correct gene action sequence in the body segmentation of Drosophila?
A) Segment polarity, pair rule, gap
B) Gap, segment polarity, pair rule
C) Gap, pair rule, segment polarity D) Hox, pair rule, segment polarity E) None of the above
C
A biologist would most likely use the technique of electroporation to A) separate proteins based on size and charge.
B) knock out a gene.
C) create antisense DNA.
D) measure expression levels of a gene. E) coax DNA into host cells.
E
Which of the following DNA sequences would most likely be recognized by a restriction enzyme?
A) AGTCGA
B) GTCTGA
C) TAAGGT D) TAGCTA E) TCGTGGA
D
The expression of some genes can be regulated in part by the pattern of alternative splicing. This is an example of
A) DNA methylation.
B) transcriptional regulation.
C) catalytic RNA activity.
D) posttranscriptional control. E) the endosymbiotic theory.
D
A biologist is using computer programs and mathematical tools to assemble a large sequence of DNA from the data provided by multiple parallel runs of next-generation sequencing. The term that best describes this biologist's field of study is
A) functional genomics.
B) comparative genomics. C) metagenomics.
D) biodiversity.
E) bioinformatics.
E
Differentiated cells in the process of forming the liver of a mouse provide an example of A) differentiation.
B) determination.
C) apoptosis.
D) induction.
E) morphogenesis.
E
If a human fetus is exposed to chemicals that lead to the overexpression of Sonic hedgehog, the baby will likely have
A) webbed fingers and toes.
B) two thumbs on each hand.
C) two "little fingers" on each hand. D) an elongated neck.
E) a shortened neck.
C
The HIV virus that causes AIDS is a(n) A) arbovirus.
B) double-stranded DNA virus. C) single-stranded DNA virus. D) porcine virus.
E) retrovirus.
E
Which of the following statements about microRNAs is false?
A) They are easy to detect.
B) They are small (less than 50 nucleotides in length).
C) Any particular microRNA can regulate the expression of many target genes. D) They are transcribed.
E) All of the above are true; none is false.
A
Which of the following characteristics would not be useful in a vector? A) A recognition sequence for a restriction enzyme
B) Large size relative to the host chromosomes
C) The ability to replicate independently inside the host cell
D) S reporter gene
E) All of the above are useful attributes of a vector.
B
Single nucleotide polymorphisms (SNPs)
A) can be used to map unlinked genes in order to follow the inheritance of disease
traits.
B) can be used to predict if a patient is at risk for a particular disease.
C) can be linked in order to generate gene sequences.
D) have limited sequence variations.
E) All of the above
B
In next-generation DNA sequencing technology, the PCR technique A) breaks the DNA into fragments.
B) produces many identical copies of specific DNA fragments.
C) labels each of the four nucleotides with a different marker.
D) enables overlapping sequences to be assembled into one complete sequence. E) None of the above
B
Which of the following entities act in opposite ways? A) A constitutive gene and an activator
B) A transcription factor and a constitutive gene
C) A repressor and an activator
D) A promoter and a repressor E) A promoter and an activator
C
Lowering the expression of the MyoD gene would tend to _______ the activity of cyclin-dependent kinases. This activity would tend to _______ differentiation of muscle cells.
A) increase; enhance
B) increase; retard
C) decrease; enhance
D) decrease; retard
E) decrease; have no effect on
B
Transgenic cells are created via the _______ of recombinant DNA into cells. A) recombination
B) transfection
C) ligation
D) restriction
E) complementation
B
Which of the following statements about genomes is true?
A) Most genes found in the genomes of complex multicellular organisms are not
required for survival.
B) As complexity increases from bacteria to yeast to invertebrate to vertebrate, gene
number increases more than does the size of the genome.
C) As complexity increases from bacteria to yeast to invertebrate to vertebrate, the
proportion of the genome consisting of coding sequence increases.
D) Both a and b
E) Both b and c
A
The artificial selection experiments with bristle numbers in Drosophila illustrate which of the following generalities?
A) In such experiments, it is difficult to obtain individuals with traits that fall outside
the range found in the original population.
B) Populations often contain considerable genetic variation upon which selection can
operate.
C) Such experiments usually take thousands of generations to achieve their results.
D) Mutations occur to suit the needs of the population.
E) None of the above
B
The hypothesis of neutral evolution asserts that
A) the rate of molecular mutation is influenced by natural selection.
B) most variability in the structure of molecules does not affect their functioning. C) closely related species have more similar molecular structures than do distantly
related species.
D) organisms evolved through neutral changes in their molecules. E) mutations neither add nor subtract amino acids from molecules.
B
A small population of sawflies that was once connected to a larger one but is now isolated is no longer experiencing
A) enhanced genetic drift.
B) gene flow.
C) reproductive isolation. D) natural selection.
E) genotypic equilibrium.
B
Mules are an example of which type of reproductive isolation? A) Low hybrid zygote viability
B) Temporal isolation
C) Postzygotic isolation
D) All of the above E) None of the above
C
The sizes of horns in males of a particular beetle have an interesting distribution: the highest frequencies are around 15 millimeters and 30 millimeters, with few individuals in between. Based on this observation, which of the following modes of selection is most likely to be operating on these horns?
A) Stabilizing selection B) Directional selection C) Concentrated selection D) Disruptive selection E) Purifying selection
D
Which type of speciation is most common among flowering plants? A) Geographic
B) Sympatric
C) Allopatric
D) Disruptive
E) None of the above
B
Oxygen in Earth's atmosphere was
A) generated, in part, by photosynthetic cyanobacteria.
B) generated abiotically.
C) generated by nonphotosynthetic bacteria.
D) present in high amounts before the origin of life.
E) present in low amounts when larger eukaryotes evolved.
A
In a hypothetical population of sawflies, 20 percent of the population is homozygous for allele A and 45 percent is homozygous for allele a. Assuming that A and a are the only alleles at this locus, what percent of the population is heterozygous?
A) 10 percent
B) 20 percent
C) 35 percent
D) 45 percent
E) Insufficient information is given to answer the question.
C
The wasp genus Nasonia contains all of the descendants of the members' common ancestor. This genus therefore would be called
A) a synapomorphy.
B) a polyphyly.
C) a clade.
D) parsimonious. E) self-compatible.
C
Which of the following statements about biological evolution is false? A) Species change over time.
B) Natural selection produces changes in species.
C) Individuals in a population evolve.
D) Different species may share a common ancestor. E) Most populations are genetically diverse.
C
Which of the following is not a condition that must be met for a population to be at Hardy-Weinberg equilibrium?
A) Absence of gene flow
B) Absence of differential survival among genotypes
C) Random mating of individuals with respect to genotype
D) Absence of genetic drift that would cause chance fluctuations of allele frequencies E) Small population size
E
An evolutionary trend toward shorter legs is observed in a rodent. Which of the following processes is the most likely explanation for this pattern?
A) Genetic drift
B) Stabilizing selection
C) Directional selection D) All of the above
E) None of the above
C
Random genetic drift would probably have its greatest effect on a A) small, isolated population.
B) large population in which mating is nonrandom.
C) large population in which mating is random.
D) large population with regular immigration from a neighboring population. E) large population with a high mutation rate.
A
The experiments by Rice and Salt with fruit flies showed that
A) speciation can be studied in the lab.
B) the evolution of reproductive isolation requires more than one hundred generations. C) acetyldehyde can be used to keep fly populations from becoming species.
D) Both a and b
E) Both a and c
A
Geographic isolation
A) Is the basis of allopatric speciation.
B) always results in the formation of new species.
C) is required for speciation.
D) does not cause a decreased probability, over time, that members of two separated
populations can mate.
E) has the same effects on all organisms.
A
Despite being incomplete as a whole, the fossil record is rather detailed for A) soft-bodied insects.
B) cnidarians and sponges.
C) most terrestrial animals.
D) hard-shelled mollusks. E) Both c and d
D
Gene duplication can
A) occur by duplication of an entire diploid genome.
B) result in the formation of pseudogenes.
C) result in genes that are lost from the genome.
D) lead to the evolution of genes that code for proteins with new functions. E) All of the above
E
Which of the following best describes natural selection?
A) Chance variations in traits
B) The differential survival and reproduction of individuals
C) The processes that lead individuals to resemble their parents D) The potential for all species to increase rapidly in number E) The immutability of species
B
Genes from many isolates of the influenza virus have been sequenced. In certain regions of the genome, nonsynonymous substitutions have been found to occur much more frequently than synonymous substitutions. From this pattern we can infer that
A) a great deal of genetic drift is taking place.
B) most of the amino acid changes are neutral.
C) strong stabilizing selection is acting on this gene.
D) strong selection for change (directional selection) is acting on this gene. E) mutations that change the amino acid are disadvantageous.
D
Shared derived traits are also known as A) homoplasies.
B) synapomorphies.
C) sympatries.
D) homologies. E) paraphylies.
B
If the half-life of a radioactive substance is 600 years, what fraction of the original material is left after 1,800 years?
A) One-half
B) One-fourth
C) One-eighth
D) One-sixteenth
E) None of the above
C
Suppose you were to drill a hole toward the center of Earth. Which of the following is the correct order of the layers you would encounter?
A) Magma, mantle, lithospheric plate
B) Mantle, magma, lithospheric plate
C) Lithospheric plate, magma, mantle D) Lithospheric plate, mantle, magma E) Mantle, lithospheric plate, magma
C
If variation at a given locus has no effect on the phenotype of individuals, which of the following evolutionary processes will still occur at that locus?
A) Genetic drift
B) Natural selection
C) Nonrandom mating D) Both a and b
E) None of the above
A
If a population with two alleles is at Hardy-Weinberg equilibrium and the frequency of one allele is 0.7, what is the heterozygote frequency?
A) 0.7
B) 0.42
C) 0.3
D) 0.21
E) Insufficient information is given to answer the question.
B
What is the critical distinction between allopolyploidy and autopolyploidy?
A) Allopolyploidy involves disruptive selection.
B) Autopolyploidy involves disruptive selection.
C) The mode of speciation in allopolyploidy is allopatric rather than sympatric.
D) Autopolyploidy requires genetic contribution from two different parental species. E) Allopolyploidy requires genetic contribution from two different parental species.
E
Which of the following is a likely reason for the diversification of Lake Malawai cichilds?
A) Habitat specialization
B) Male competition for females C) Polyploidy
D) Both a and b
E) Both b and c
D
The artificial selection experiments with bristle numbers in Drosophila illustrate which of the following generalities?
A) In such experiments, it is difficult to obtain individuals with traits that fall outside
the range found in the original population.
B) Populations often contain considerable genetic variation upon which selection can
operate.
C) Such experiments usually take thousands of generations to achieve their results.
D) Mutations occur to suit the needs of the population.
E) None of the above
B
What was Darwin's explanation for the evolution of bright colors and other apparently useless (and potentially deleterious) but conspicuous characters in males of many species?
A) Stabilizing selection
B) Genetic drift
C) Sexual selection
D) Disruptive selection E) Gene flow
C
Which of the following is not a prezygotic reproductive isolating barrier? A) Behavioral isolation
B) Mechanical isolation
C) Hybrid infertility
D) Temporal isolation
E) All of the above are prezygotic reproductive isolating barriers.
C
Most of human evolution has occurred during the A) Paleozoic era.
B) Devonian period.
C) Quaternary period.
D) Carboniferous period. E) Cretaceous period.
C
Rocks that are formed when grains accumulate at the bottom of bodies of water are called _______ rocks
A) igneous
B) sedimentary
C) strata D) tertiary E) deep
B
Snakes, which lack limbs, evolved from vertebrates that had legs. This is an example of A) convergent evolution.
B) an evolutionary reversal.
C) a synapomorphy.
D) a homology.
E) None of the above
B
In a hypothetical population of tree swallows, 18 individuals are homozygous for the c4 allele, 22 individuals are heterozygous for the allele, and 10 individuals lack the allele. What is the frequency of the c4 allele?
A) 0.29
B) 0.36 C) 0.40 D) 0.58 E) 0.80
D
In the Dobzhansky-Muller model, an ancestral population (aabb) splits into 2 lineages. Different mutations produce different new alleles in each population (Aabb in one population, aaBb in the other). Which genotype would not be viable?
A) aabb
B) Aabb
C) aaBB
D) AaBb
E) Both c and d
D
Supporting the claim that a meteorite caused the mass extinction at the end of the Cretaceous period, abnormally high concentrations of _______ have been found in rocks dating from that time.
A) lithium
B) iridium C) mercury D) nickel E) tungsten
B
The half-life of carbon-14 is 5,700 years. If 10 percent of the original carbon-14 is left in a structure, that structure is _______ years old.
A) less than 2,850
B) about 5,700
C) between 11,400 and 17,100
D) between 17,100 and 22,800 E) about 57,000
D
As adaptations for flight, the wings of bats and the wings of birds are an example of A) synapomorphy.
B) evolutionary reversal.
C) monophyly.
D) paraphyly.
E) convergent evolution.
E
The ratio of 14C to its stable isotope, carbon-12 (12C), is relatively constant in living organisms and their environment; however, this changes once an organism dies. In a fossil less than 50,000 years old, what would the ratio of 14C to 12C be?
A) The ratio of 14C to 12C would be higher because the 12C is not replenished after
death.
B) The ratio of 14C to 12C would be lower because 14C is not replenished after death
C) The ratio would be equal.
D) Fossils less than 50,000 years old cannot be dated using this method.
E) None of the above
B
Which of the following is changing most rapidly during recent history? A) Oxygen levels
B) Carbon dioxide levels
C) Sea level
D) Global temperature E) All of the above
B
Why are assemblages of fossils seen in successive geological periods so different?
A) Rapid continental drift has altered the positions of continents such that the strata
represent different locations on Earth.
B) Rapid bursts of evolution have occurred due to changes in oxygen concentrations.
C) Mass extinctions and the subsequent rebound of biological diversity have brought
about sudden changes in the assemblages.
D) Organisms continue to evolve during periods when fossilization does not occur.
E) None of the above; fossil assemblages across successive strata blend into one
another, and there are no sharp breaks.
C
The species definition that includes similarity of appearance among individual members is the basis for
A) the lineage species concept.
B) reproductive isolation.
C) the morphological species concept. D) centric fusion.
E) the biological species concept.
C
The sudden disappearance of the dinosaurs some 65 mya may have been the result of A) Earth's collision with a large meteorite.
B) slow climate changes due to planetary cooling.
C) competition from better adapted organisms.
D) the rise of birds and mammals. E) the formation of Pangaea.
A
Despite inhabiting overlapping ranges, the western spotted skunk and the eastern spotted skunk do not interbreed, partly because the western species breeds in early fall and the eastern species breeds in late winter to early spring. This is an example of _______ isolation.
A) chemical B) gametic
C) postzygotic D) temporal E) mechanical
D
The common ancestor of all of the species displayed in a phylogenetic tree lies at the _______ of the tree.
A) node
B) root
C) tip
D) taxon
E) None of the above
B
Which of the following is formed when two branches diverge in a phylogenetic tree? A) A population
B) A lineage
C) A node
D) All of the above E) None of the above
C
Two species of monkeyflowers have diverged in the characters of their flower such that they are now pollinated by different animals. This is an example of _______ isolation. A) behavioral
B) allopatric
C) mechanical D) temporal E) sympatric
C
It is difficult to apply the biological species concept to groups of organisms that A) are asexual.
B) produce hybrids only in captivity. C) show little morphological diversity. D) exist only in the fossil record.
E) Both a and d
E
Due to various causes, including DDT poisoning, the population size of whooping cranes was reduced to about a dozen during the 1970s. The population size has since rebounded, and there are now hundreds of whooping cranes. Which of the following would you not expect to see in the current populations of whooping cranes?
A) Very low levels of genetic variation
B) Very few heterozygous individuals
C) Differences from historical populations in terms of allele frequencies
D) Considerable genetic polymorphism
E) All of the above would be seen in the current populations of whooping cranes.
D
The evolutionary relationship among organisms is known as A) taxonomy.
B) phylogeny.
C) paraphyly.
D) synapomorphy. E) homoplasy.
B
Near the ends of several geological periods, including the Devonian, Permian, and the Triassic, sea level _______ dramatically, most likely due to _______.
A) rose; increased glaciation
B) rose; decreased glaciation
C) rose; cessation of continental drift D) fell; increased glaciation
E) fell; cessation of continental drift
D
Synonymous substitutions are possible because
A) of the operation of the Hardy-Weinberg principle.
B) most changes in DNA are either deleterious or selectively neutral. C) mutation rates are low.
D) most amino acids are specified by more than one codon.
E) None of the above
D
1.
The evolutionary importance of plant tissue composed of tracheids is that it provides
A)a vascular system and structural support.
B)structural support and increased growth.
C)enhanced photosynthesis and structural support.
D)enhanced photosynthesis and a vascular system.
E)None of the above
A
The common ancestry (monophyly) of the three domains (Archaea, Bacteria, and Eukarya) is confirmed by
A)the similar appearances of different organisms.
B)ample fossil evidence.
C)DNA as the genetic material that encodes for proteins.
D)All of the above
E) None of the above
C
The microbial eukaryotes that are responsible for sleeping sickness and those that are responsible for malaria
A)are both alveolates.
B)both have insect vectors for transmission to humans.
C)cause the same symptoms.
D)both have gametocyte life stages.
E)All of the above
B
Dinoflagellates are common endosymbionts of
A) coral.
B) fungi.
C) other dinoflagellates.
D) tertiary endosymbionts.
E) None of the above
A
Actinobacteria
A) are photoheterotrophs.
B) are the source of many important antibiotics.
C) are Gram-negative bacteria.
D) were once classified as protists.
E)are the only bacteria that divide by mitosis.
B
Asexually reproduced groups of nearly identical organisms are known as
A) fruiting bodies.
B) buds.
C) clonal lineages.
D) myxamoebas.
E) conjugates.
C
Before they had the ability to decipher nucleotide sequences, biologists classified prokaryotes based on several characteristics. Which of the following was not one of these characteristics?
A) Nutritional requirements
B) Phenotypic characteristics like shape or color
C) Sensitivity to antibiotics
D) Modes of locomotion
E) Multiple genes
E
A universal feature of the life cycles of land plants is
A)morphologically identical gametophyte and sporophyte stages.
B) genetically identical gametophyte and sporophyte stages.
C) alteration of generations between haploid gametophytes and diploid sporophytes.
D) All of the above
E) None of the above
C
Which of the following features is a synapomorphy of the animals?
A) Cells that contain chitin
B) Vascular systems
C) Similarities in their Hox genes
D) Bilateral symmetry
E) Spiral cleavage
C
A pseudocolomate animal lacks a
A) body cavity.
B) fluid-filled body cavity.
C) fluid-filled body cavity lined on the outside with mesoderm.
D) fluid-filled body cavity lined on the outside and inside with mesoderm.
E) pseudocoel.
D
The calcification of an internal skeleton is characteristic of the
A) urochordates.
B) echinoderms.
C) hemichordates.
D) brachiopods.
E)phoronids.
B
Which of the following groups of protists secretes an external "shell" of silica (silicon dioxide)?
A) Paramecium
B) Diatoms
C) Red algae
D) Euglenids
E) Amoebozoans
B
The large and remarkable pogonophoran annelids live near deep-ocean hydrothermal (volcanic) vents where food items are scarce. Many species are able to obtain enough nutrition because
A) they are able to conduct photosynthesis.
B) their tissues harbor endosymbiotic bacteria that fix carbon by oxidizing hydrogen sulfide and methane.
C) they fix carbon from the minerals found in the ocean's muddy floor.
D) they filter algae out of ocean water.
E) they feed on dead fish that sink to the ocean floor.
B
Cephalization is most commonly associated with
A) spherical symmetry.
B) radial symmetry.
C) sessile animals.
D) bilateral symmetry.
E) lophophorate animals.
D
Which of the following is a broad nutritional category of prokaryotes that is recognized by biologists?
A)Physioautotrophs
B) Heteroautotrophs
C)Chemolithotrophs
D)Both a and b
E) Both a and c
C
The sister group to the vertebrates includes an animal called a(n) _______, which produces large amounts of slime as a defense mechanism.
A) hagfish
B) lamprey
C) eel
D) slug
E) ascidian
A
Stomata appear to have arisen first in the
A) hornworts.
B) mosses.
C) liverworts.
D) club mosses.
E) angiosperms.
B
The diversification of insects about 450 million years ago corresponded with
A) the appearance of the first land plants.
B) the evolution of cartilaginous fish.
C) the extinction of dinosaurs.
D) changes in the CO2 concentration of the atmosphere.
E) None of the above
A
Negative-sense single-stranded RNA viruses
A) have only a few genes, including one that allows them to make mRNA from their genome.
B) are responsible for causing plant diseases and are referred to as mosaic viruses.
C) regenerate themselves by reverse transcription.
D) are polyphyletic and include some that have more than a million base pairs.
E) have distinct lipids in their plasma membranes.
A
The cyanobacteria found in the internal mucilage-filled cavities of the hornworts serve to
A) provide structural support.
B) produce carbohydrates.
C) convert atmospheric nitrogen gas into a usable nutrient form.
D) convert atmospheric carbon gas into a usable nutrient form.
E) Both c and d
C
Lateral gene transfer is the process by which
A) scientists make transgenic organisms.
B) prokaryotes within a species exchange genes.
C) prokaryotes acquire DNA from a different species.
D) genes are passed to daughter cells.
E) None of the above
C
Which of the following statements about the brown algae is false?
A) They are all multicellular.
B) They use the same photosynthetic pigments as do land plants.
C) They are almost exclusively marine.
D) A few are many meters in length.
E) They are stramenopiles.
B
An animal that has a hemocoel, a chitinous exoskeleton, and a complete digestive tract is most likely a(n)
A) nematode.
B) annelid.
C) arthropod.
D) mollusk.
E) arrow worm.
C
You are rowing a boat across a marine estuary at night and see flashes of light in the water. This is most likely a result of the action of
A) dinoflagellates.
B) diatoms.
C) diplomonads.
D) Both a and b
E) Both b and c
A
In heterosporous land plants, _______ produce _______.
A) microgametophytes; eggs
B) microgametophytes; sperm
C) microgametophytes; eggs and sperm
D) megagametophytes; sperm
E)megagametophytes; eggs and sperm
B
The molluscan body plan includes three unique, shared, derived characteristics that support the monophyly of the group: the _______, the _______, and the _______.
A) foot; radula; mantle
B) foot; mantle; shell
C) visceral mass; radula; mantle
D) visceral mass; mantle; shell
E) foot; visceral mass; mantle
E
It is difficult to reconstruct the phylogenetic relationships of viruses because of their
A) small genomes.
B) diverse capsid morphologies.
C) rapid evolutionary rates.
D) Both a and b
E) Both a and c
E
Which of the following statements about bacteria is true?
A) Gram-positive bacteria have a lot of peptidoglycan in their cell walls and stain blue to purple.
B) Gram-negative bacteria have no peptidoglycan in their cell walls and stain blue to purple.
C) Gram-positive bacteria weigh more than a gram.
D) Gram-positive bacteria have relatively little peptidoglycan in their cell walls and stain pink to red.
E) Gram-negative bacteria lack a plasma membrane.
A
In the alternation of generations, the gametophyte generation is _______ and produces _______.
A) haploid; spores
B) haploid; gametes
C) diploid; spores
D) diploid; gametes
E)haploid or diploid; spores
B
Because all animals must take in nutrients from their environment and digest their food internally, the nutritional mode of animals is called
A) heterotrophic.
B) photoheterotrophic.
C) photoautotrophic.
D) chemolithotrophic.
E) chemoautotrophic.
A
Two different species of ciliate are placed in a solution with an unknown solute concentration. Ciliate A has a contractile vacuole that expels water at a rate of 5 times per minute; the contractile vacuole of ciliate B expels water 12 times per minute. Which of the following is a reasonable conclusion based on these observations?
A) Ciliate A has a greater solute concentration than ciliate B.
B) Ciliate B has a greater solute concentration than ciliate A.
C) The solution has a greater solute concentration than ciliate A.
D) The solution has a greater solute concentration than ciliate B.
E) No conclusions can be made unless we know the solute concentration of the solution.
B
Which of the following was an essential step in the evolution of eukaryotic cells?
A) The development of a nuclear envelope
B) The development of a cytoskeleton
C) The endosymbiotic acquisition of certain organelles
D) The development of a flexible cell surface
E) All of the above
E
Bacteria are known for the many roles they play in biological communities. Which of the following is the rarest role for this group of organisms?
A) Pathogen
B) Digestive aid
C) Nitrogen and sulfur processor in soils
D) Decomposer
E)Industry and agricultural use
A
Archaea is the closest sister group to the
A) bacteria.
B) bacteria and eukaryotes.
C) eukaryotes.
D) prokaryotes.
E) None of the above
C
Which of the following statements about methanogens is false?
A) Methane is their preferred carbon source.
B) They are associated with mammalian flatulence.
C) They prefer anaerobic conditions.
D) Some are thermophilic.
E) Some live in volcanic vents on the ocean floor.
A
Within vascular plants, the large, prominent plant is the _______; in nonvascular plants it is the _______.
A) gametophyte; sporophyte
B) sporophyte; gametophyte
C) gametophyte; gametophyte
D) sporophyte; sporophyte
E)None of the above
B
The ancestor of the animal clade was probably a
A) ctenophore.
B) triploblastic acoelomate with spiral cleavage.
C) ciliated protist.
D) colonial flagellated protist.
E) None of the above
D
Which of the following is not a characteristic of land plants?
A)Development from embryos protected by tissues of the parent plant
B) Cell walls containing cellulose
C) Chloroplasts containing chlorophylls a and b
D) Starch as the storage carbohydrate
E) Anaerobic respiration
E
Which of the following groups has a water vascular system?
A) Mollusks
B) Chordates
C) Annelids
D) Echinoderms
E)Hemichordates
D
All prokaryotes that use light as an energy source
A) use chlorophyll a as their photosynthetic pigment.
B) use bacteriochlorophyll as their photosynthetic pigment.
C) release oxygen gas.
D) produce particles of sulfur.
E) None of the above
E
All photosynthetic prokaryotes
A) use chlorophyll a as their photosynthetic pigment.
B) use bacteriochlorophyll as their photosynthetic pigment.
C) release oxygen gas.
D) produce particles of sulfur.
E) are photoautotrophs.
E
Which of the following is not one of the characteristics that distinguishes deuterostomes from protostomes?
A) Cleavage type
B) Ability to form a blastopore
C) Embryological origin of the mouth
D) Derivation of mesoderm
E) Position of the nervous system (dorsal/ventral)
B
Which of the following are synapomorphies for both gymnosperms and angiosperms?
A) Seeds
B) Heterospory
C) Flowers
D) Both a and b
E) Both a and c
D
The terms "acoelomate," "pseudocoelomate," and "coelomate" refer to
A) levels of cephalization.
B) the origin of the blastopore.
C) ectoderm, mesoderm, and endoderm.
D) the body cavity of animals.
E)the vertebrate body plan.
D
Nonvascular land plants have never evolved to the size of vascular plants, most likely because they lack
A) a photosynthetic mechanism.
B) an efficient mode of respiration.
C) an efficient system for conducting water and minerals.
D) mechanisms for nutrient and water absorption.
E) All of the above
C
Which of the following is not one of the traits that unite the protostomes?
A) Dorsal nervous system
B) Anterior brain
C) Bilaterally symmetrical body plan
D) Development of a mouth from a blastopore (in many species)
E) All of the above are traits that unite protostomes.
A
Which of the following groups exhibits exclusively radial symmetry?
A) Loboseans
B) Foraminiferans
C) Stramenophiles
D) Radiolarians
E) Heteroloboseans
D
Which of the following is not considered part of the body plan of an organism?
A) The symmetry of the body
B) The structure of the body cavity
C) The segmentation of the body
D) External appendages
E) The larval morphology
E
A eukaryotic organism that undergoes alternation of generations in which different generations do not resemble each other morphologically is referred to as
A) homomorphic.
B) heteromorphic.
C) isomorphic.
D) anisomorphic.
E) gametophytic.
B
Plants invaded the land sometime during the Paleozoic era. In order to evolve and thrive on land, plants had to develop
A) photosynthetic pigments and mechanisms for transporting water and minerals to aerial parts.
B) starch for carbohydrate storage and mechanisms for transporting water and minerals to aerial parts.
C) physical support structures and mechanisms for gamete dispersal.
D) photosynthetic pigments that are not dependent on an aqueous environment and starch for carbohydrate storage.
E) physical support structures and alternation of generations.
C