BIO 101 - Quiz 4 - Chapters 11, 12, 14

D) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

1) Garrod hypothesized that inherited diseases such as alkaptonuria, the inability to metabolize the chemical alkapton, occur because A) metabolic enzymes require vitamin cofactors, and affected individuals have significant nutritional deficiencies. B) many metabolic enzymes use DNA as a cofactor, and affected individuals have mutations that prevent their enzymes from interacting efficiently with DNA. C) certain metabolic reactions are carried out by ribozymes, and affected individuals lack key splicing factors. D) genes dictate the production of specific enzymes, and affected individuals have genetic defects that cause them to lack certain enzymes.

C) A monohybrid cross involves organisms that are heterozygous for one character.

1) What do we mean when we use the term monohybrid cross? A) A monohybrid cross involves a single parent. B) A monohybrid cross produces a single offspring. C) A monohybrid cross involves organisms that are heterozygous for one character. D) A monohybrid cross is performed for one generation. E) A monohybrid cross results in a 9:3:3:1 phenotype ratio in the F2 offspring.

B) The gene involved is on the X chromosome.

1) When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result? A) The gene involved is on the Y chromosome. B) The gene involved is on the X chromosome. C) The gene involved is on an autosome, but only in males. D) Eye color in flies is a multifactorial trait.

B) It might allow the polymerase to recognize different promoters under certain environmental conditions.

10) RNA polymerase in a prokaryote is composed of several subunits. Most of these subunits are the same for the transcription of any gene, but one, known as sigma, varies considerably. Which of the following is the most probable advantage for the organism in having such variability in RNA polymerase? A) It might allow the translation process to vary from one cell to another. B) It might allow the polymerase to recognize different promoters under certain environmental conditions. C) It might allow the polymerase to react differently to each stop codon. D) It might alter the rate of translation and of exon splicing.

C) 50%

10) When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? A) 0% B) 25% C) 50% D) 75%

B) One-half of the daughters of an affected man would have this condition.

11) Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their 20s. How likely is it for a woman to have this condition? A) Women can never have this condition. B) One-half of the daughters of an affected man would have this condition. C) One-fourth of the daughters of an affected father and a carrier mother could have this condition. D) Very rarely: it is rare that an affected male would mate with a carrier female. E) Only if a woman is XXX could she have this condition.

C) RNA polymerase II

11) In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA known as pre-mRNA? A) ligase B) RNA polymerase I C) RNA polymerase II D) RNA polymerase III

C) traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1.

11) Mendel accounted for the observation that traits that had disappeared in the F1 generation reappeared in the F2 generation by proposing that A) new mutations were frequently generated in the F2 progeny, "reinventing" traits that had been lost in the F1. B) the mechanism controlling the appearance of traits was different between the F1 and the F2 plants. C) traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1. D) the traits were lost in the F1 due to dominance of the parental traits. E) members of the F1 generation had only one allele for each trait, but members of the F2 had two alleles for each trait.

D) All of the genes controlling the traits behaved as if they were located on different chromosomes.

12) The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following? A) None of the traits obeyed the law of segregation. B) Some traits obeyed the law of segregation and some did not. C) All of the genes controlling the traits were located on the same chromosome. D) All of the genes controlling the traits behaved as if they were located on different chromosomes.

D) several transcription factors

12) Transcription in eukaryotes requires which of the following in addition to RNA polymerase? A) the protein product of the promoter B) start and stop codons C) ribosomes and tRNA D) several transcription factors E) aminoacyl-tRNA synthetase

A) activation of the XIST gene on the X chromosome that will become the Barr body

12) What event causes all female mammals to have one active X chromosome per cell instead of two? A) activation of the XIST gene on the X chromosome that will become the Barr body B) activation of the BARR gene on one X chromosome, which then becomes inactive C) crossing over between the XIST gene on one X chromosome and a related gene on an autosome D) inactivation of the XIST gene on the X chromosome derived from the male parent

C) Any mutation in the sequence is selected against.

13) A part of the promoter, called the TATA box, is said to be highly conserved in evolution. Which of the following might this illustrate? A) The sequence evolves very rapidly. B) The sequence does not mutate. C) Any mutation in the sequence is selected against. D) The sequence is found in many but not all promoters. E) The sequence is transcribed at the start of every gene.

D) anaphase I of meiosis

13) Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division? A) prophase I of meiosis B) anaphase II of meiosis C) metaphase I of meiosis D) anaphase I of meiosis

A) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

13) Which of the following statements correctly describes linkage? A) The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. B) The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. C) All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome. D) Linked genes are found on different chromosomes.

A) The two genes are closely linked on the same chromosome.

14) How would one explain a testcross involving F1 dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced? A) The two genes are closely linked on the same chromosome. B) The two genes are linked but on different chromosomes. C) Recombination did not occur in the cell during meiosis. D) Both of the characters are controlled by more than one gene.

C) alignment of synapsed pairs of homologous chromosomes on the metaphase plate

14) Mendel's second law of independent assortment has its basis in which of the following events of meiosis I? A) synapsis of homologous chromosomes B) crossing over C) alignment of synapsed pairs of homologous chromosomes on the metaphase plate D) separation of homologs at anaphase E) separation of cells at telophase

A) It is the recognition site for a specific transcription factor.

14) Which of the following best describes the significance of the TATA box in eukaryotic promoters? A) It is the recognition site for a specific transcription factor. B) It sets the reading frame of the mRNA. C) It is the recognition site for ribosomal binding. D) It signals the end of the nucleotide sequence of the gene.

C) a bacterial promoter sequence

15) In order for a eukaryotic gene to be engineered into a bacterial colony to be expressed, what must be included in addition to the coding exons of the gene? A) the introns B) eukaryotic polymerases C) a bacterial promoter sequence D) eukaryotic ribosomal subunits E) eukaryotic tRNAs

A) The two genes are likely to be located on different chromosomes.

15) What does a frequency of recombination of 50% indicate? A) The two genes are likely to be located on different chromosomes. B) All of the offspring have combinations of traits that match one of the two parents. C) The genes are located on sex chromosomes. D) Independent assortment is hindered.

D) One allele was dominant.

15) Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? A) No genes interacted to produce the parental phenotype. B) Each allele affected phenotypic expression. C) The traits blended together during fertilization. D) One allele was dominant. E) Phenotype was not dependent on genotype.

D) 1/2

16) Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails? A) 1/16 B) 3/16 C) 3/8 D) 1/2 E) 9/16

B) 3' to 5' along the template strand

16) RNA polymerase moves in which direction along the DNA? A) 5' to 3' along whichever strand it's on B) 3' to 5' along the template strand C) 5' to 3' along the template strand D) 5' to 3' along the double-stranded DNA E) 3' to 5' along the nontemplate strand

D) Gene A is assorting independently of genes B and C, which are linked.

16) Three genes (A, B, and C) at three loci are being mapped in a particular species. Each gene has two alleles, one of which results in a phenotype that is markedly different from the wild type. The unusual allele of gene A is inherited with the unusual allele of gene B or C about 50% of the time. However, the unusual alleles of genes B and C are inherited together 14.4% of the time. Which of the following statements describes what is happening regarding the inheritance of these genes? A) The three genes are showing independent assortment. B) The three genes are linked. C) Gene A is linked but genes B and C are not. D) Gene A is assorting independently of genes B and C, which are linked. E) Gene A is located 14.4 map units from genes B and C.

E) 0

17) In certain plants, the tall trait is dominant to the short trait. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? A) 1 B) 1/2 C) 1/4 D) 1/6 E) 0

B) 1% frequency of recombination between two genes

17) One map unit is equivalent to which of the following values? A) the physical distance between two linked genes B) 1% frequency of recombination between two genes C) 1 nanometer of distance between two genes D) the distance between a pair of homologous chromosomes E) the recombination frequency between two genes assorting independently

D) It helps protect the mRNA from degradation by hydrolytic enzymes.

17) Which of the following is a function of a poly-A tail in mRNA? A) It adds the modified guanine to the 3' end of the mRNA. B) It indicates the site of translational termination. C) It is a sequence that codes for the binding of RNA polymerase to the DNA. D) It helps protect the mRNA from degradation by hydrolytic enzymes.

E) 1/64

18) In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? A) 1/4 B) 1/8 C) 1/16 D) 1/32 E) 1/64

B) an RNA with enzymatic activity

18) What is a ribozyme? A) an enzyme that uses RNA as a substrate B) an RNA with enzymatic activity C) an enzyme that catalyzes the association between the large and small ribosomal subunits D) an enzyme that synthesizes RNA as part of the transcription process E) an enzyme that synthesizes RNA primers during DNA replication

C) Crossovers between these genes result in chromosomal exchange.

18) Which of the following events causes recombination between linked genes to occur? A) Mutation on one homolog is different from that on the other homolog. B) When genes are linked they always "travel" together at anaphase. C) Crossovers between these genes result in chromosomal exchange. D) Nonrecombinant chromosomes break and then re-join with one another.

A) many noncoding stretches of nucleotides are present in eukaryotic DNA.

19) A eukaryotic transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that A) many noncoding stretches of nucleotides are present in eukaryotic DNA. B) there is redundancy in the genetic code. C) many nucleotides are needed to code for each amino acid. D) there are termination exons near the beginning of mRNA.

C) 3/4

19) Given the following cross between parents of the genotypes AABBCc × AabbCc, assume simple dominance for each trait and independent assortment. What proportion of the progeny will be expected to phenotypically resemble the first parent? A) 1/4 B) 1/8 C) 3/4 D) 3/8 E) 1

C) New allele combinations are acted upon by natural selection.

19) Why does recombination between linked genes continue to occur? A) Recombination is a requirement for independent assortment. B) Recombination must occur or genes will not assort independently. C) New allele combinations are acted upon by natural selection. D) Without recombination there would be an insufficient number of gametes.

C) A dihybrid cross involves organisms that are heterozygous for two characters.

2) What do we mean when we use the term dihybrid cross? A) A dihybrid cross involves two parents. B) A dihybrid cross produces two offspring. C) A dihybrid cross involves organisms that are heterozygous for two characters. D) A dihybrid cross is performed for two generations. E) A dihybrid cross results in a 3:1 phenotype ratio in the F2 offspring.

B) Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis.

2) Which of the following statements describes the chromosome theory of inheritance as expressed in the early twentieth century? A) Individuals inherit particular chromosomes attached to genes. B) Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis. C) Homologous chromosomes give rise to some genes and crossover chromosomes to other genes. D) No more than a single pair of chromosomes can be found in a healthy normal cell. E) Natural selection acts on certain chromosome arrays rather than on genes.

C) RNA

20) During splicing, which molecular component of the spliceosome catalyzes the excision reaction? A) protein B) DNA C) RNA D) lipid E) sugar

A) The frequency of crossing over varies along the length of the chromosome.

20) Map units on a linkage map cannot be relied upon to calculate physical distances on a chromosome for which of the following reasons? A) The frequency of crossing over varies along the length of the chromosome. B) The relationship between recombination frequency and map units is different in every individual. C) Physical distances between genes change during the course of the cell cycle. D) The gene order on the chromosomes is slightly different in every individual.

C) the probability that either one of two mutually exclusive events will occur

20) Which of the following is the best description of the addition rule of probability? A) the probability that two or more independent events will both occur B) the probability that two or more independent events will both occur in the offspring of one set of parents C) the probability that either one of two mutually exclusive events will occur D) the probability of producing two or more heterozygous offspring

A) The likelihood of a crossover event between these two genes is low.

21) What is the reason that closely linked genes are typically inherited together? A) The likelihood of a crossover event between these two genes is low. B) The number of genes in a cell is greater than the number of chromosomes. C) Chromosomes are unbreakable. D) Alleles are paired together during meiosis. E) Genes align that way during metaphase I of meiosis.

D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both.

21) Which of the following calculations require that you utilize the addition rule? A) Calculate the probability of black offspring from the cross AaBb × AaBb, when B is the symbol for black. B) Calculate the probability of children with both cystic fibrosis and polydactyly when parents are each heterozygous for both genes. C) Calculate the probability of each of four children having cystic fibrosis if the parents are both heterozygous. D) Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents are each heterozygous for both.

B) It can allow the production of proteins of different sizes and functions from a single mRNA.

21) Which of the following statements correctly describes alternative RNA splicing? A) It is a mechanism that can increase the rate of transcription. B) It can allow the production of proteins of different sizes and functions from a single mRNA. C) It allows the production of similar proteins from different RNAs. D) It increases the rate of transcription.

D) The molecule is degraded by hydrolytic enzymes because it is no longer protected at the 5' end and the 3' end.

22) In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find? A) The mRNA would not be transported out of the nucleus. B) The cell recognizes the absence of the tail and adds a new poly-A tail to the mRNA. C) The molecule is digested by restriction enzymes in the nucleus. D) The molecule is degraded by hydrolytic enzymes because it is no longer protected at the 5' end and the 3' end. E) The molecule attaches to a ribosome and is translated, but more slowly.

C) It is pleiotropic.

22) Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes eye problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information? A) It is recessive. B) It is dominant. C) It is pleiotropic. D) It is epistatic.

B) Drosophila genes cluster into four distinct groups of linked genes.

22) Sturtevant provided genetic evidence for the existence of four pairs of chromosomes in Drosophila in which of the following ways? A) There are four major functional classes of genes in Drosophila. B) Drosophila genes cluster into four distinct groups of linked genes. C) The overall number of genes in Drosophila is a multiple of four. D) The entire Drosophila genome has approximately 400 map units. E) Drosophila genes have, on average, four different alleles.

C) One-fourth of the gametes descended from cell X will be n + 1, 1/4 will be n - 1, and 1/2 will be n.

23) If cell X enters meiosis, and nondisjunction of one chromosome occurs in one of its daughter cells during meiosis II, what will be the result at the completion of meiosis? A) All the gametes descended from cell X will be diploid. B) Half of the gametes descended from cell X will be n + 1, and half will be n - 1. C) One-fourth of the gametes descended from cell X will be n + 1, 1/4 will be n - 1, and 1/2 will be n. D) There will be three extra gametes. E) Two of the four gametes descended from cell X will be haploid, and two will be diploid.

B) roan × roan

23) In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (CRCr) offspring of red (CRCR) and white (CrCr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? A) red × white B) roan × roan C) white × roan D) red × roan

C) 5' UTR E1 E2 E3 E4 UTR 3'

23) Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol? A) 5' UTR I1 I2 I3 UTR 3' B) 5' E1 E2 E3 E4 3' C) 5' UTR E1 E2 E3 E4 UTR 3' D) 5' I1 I2 I3 3' E) 5' E1 I1 E2 I2 E3 I3 E4 3'

D) translocation

24) One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called? A) deletion B) transversion C) inversion D) translocation E) duplication

D) to each end of an intron

24) Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Where on a pre-mRNA transcript does a spliceosome bind? A) to the exons B) to the 5' UTR C) to the 3' UTR D) to each end of an intron

C) pleiotropy

24) Which of the following describes the ability of a single gene to have multiple phenotypic effects? A) incomplete dominance B) multiple alleles C) pleiotropy D) epistasis

D) exchange of nonhomologous chromosome fragments

25) A translocation causes which of the following results? A) deletion only B) exchange of homologous chromosome fragments C) nondisjunction D) exchange of nonhomologous chromosome fragments

C) pleiotropy

25) Cystic fibrosis affects the lungs, the pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this expression of phenotypes? A) incomplete dominance B) multiple alleles C) pleiotropy D) epistasis E) codominance

D) inclusion of I1 in the mRNA

25) Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I1). Which of the following results might occur? A) loss of the gene product B) loss of E1 C) premature stop to the mRNA D) inclusion of I1 in the mRNA

B) Removal of the 5' UTR also removes the 5' cap, so the mRNA may be quickly degraded by hydrolytic enzymes.

26) Use the following model of a eukaryotic transcript to answer the question. E1-4 refer to the exons and I1-3 refer to the introns in the pre-mRNA transcript. 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Suppose that an induced mutation removes most of the 5' end of the 5' UTR. What might be the result of this removal? A) Removal of the 5' UTR has no effect because the exons remain intact. B) Removal of the 5' UTR also removes the 5' cap, so the mRNA may be quickly degraded by hydrolytic enzymes. C) The 3' UTR will duplicate and one copy will replace the 5' end. D) The first exon will not be read because I1 will now serve as the UTR.

E) skin pigmentation in humans

26) Which of the following traits is an example of polygenic inheritance? A) pink flowers in snapdragons B) the ABO blood group in humans C) Huntington's disease in humans D) white and purple flower color in peas E) skin pigmentation in humans

D) Environmental factors such as soil pH affect phenotype.

27) Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others produce pink flowers. This can be best explained by which of the following statements? A) Multiple alleles are involved in the expression of the phenotype. B) The allele for blue hydrangea is completely dominant. C) The alleles are codominant. D) Environmental factors such as soil pH affect phenotype.

D) at certain sequences along an intron

27) When the spliceosome binds to a pre-mRNA transcript, where does it typically attach? A) to the exons B) to the 5' UTR C) to the 3' UTR D) at certain sequences along an intron

B) removal of the 5' cap

28) Which of the following experimental procedures is most likely to speed up mRNA degradation in a eukaryotic cell? A) lengthening of the poly-A tail B) removal of the 5' cap C) removal of C nucleotides D) removal of one or more exons

B) In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing.

28) Which of the following statements provides an example of epistasis? A) Recessive genotypes for each of two genes (aabb) result in an albino corn snake. B) In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing. C) In Drosophila (fruit flies), white eyes can be due to a combination of multiple genes. D) In cacti, there are several genes for the type of spines.

C) UUU.

29) A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is A) TTT. B) UUA. C) UUU. D) AAA. E) either UAA or TAA, depending on first base wobble.

B) Design a test for identifying heterozygous carriers of the allele.

29) A scientist discovers a DNA-based test for one allele of a particular gene. This and only this allele, if homozygous, produces an effect that results in death at or about the time of birth. Which of the following statements describes the best use of this discovery? A) Screen all newborns of an at-risk population. B) Design a test for identifying heterozygous carriers of the allele. C) Introduce a normal allele into deficient newborns. D) Follow the segregation of the allele during meiosis.

D) males are hemizygous for the X chromosome.

3) Males are more often affected by sex-linked traits than females because A) male hormones such as testosterone often alter the effects of mutations on the X chromosome. B) female hormones such as estrogen often compensate for the effects of mutations on the X chromosome. C) X chromosomes in males generally have more mutations than X chromosomes in females. D) males are hemizygous for the X chromosome. E) mutations on the Y chromosome often worsen the effects of X-linked mutations.

B) Traits are inherited in discrete units, and are not the results of the "blending" of traits.

3) What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? A) There is considerable genetic variation in garden peas. B) Traits are inherited in discrete units, and are not the results of the "blending" of traits. C) Recessive genes occur more frequently in the F1 generation than do dominant ones. D) Genes are composed of DNA. E) An organism that is homozygous for many recessive traits is at a disadvantage.

D) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

30) Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following? A) binding of ribosomes to mRNA B) shape of the A and P sites of ribosomes C) attachment of amino acids to tRNAs D) bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

C) Darwin's explanation of natural selection

30) The frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following concepts? A) Mendel's law of independent assortment B) Mendel's law of segregation C) Darwin's explanation of natural selection D) Darwin's observations of competition

D) nondisjunction or translocation in either parent

30) What is the source of the extra chromosome 21 in an individual with Down syndrome? A) nondisjunction in the mother only B) nondisjunction in the father only C) duplication of the chromosome D) nondisjunction or translocation in either parent

E) No groups have a significantly higher frequency.

31) Down syndrome has a frequency in the U.S. population of ~1/830 live births. In which of the following groups would you expect this frequency to be significantly higher? A) people in Latin or South America B) the Inuit and other peoples in very cold habitats C) people living in equatorial areas of the world D) very small population groups E) No groups have a significantly higher frequency.

A) GTP provides the energy for the formation of the initiation complex, using initiation factors.

31) What is the function of GTP in translation? A) GTP provides the energy for the formation of the initiation complex, using initiation factors. B) GTP is hydrolyzed to provide phosphate groups for tRNA binding. C) GTP is hydrolyzed to provide energy for breaking peptide bonds. D) GTP supplies phosphates and energy to make ATP from ADP.

D) One member of the couple underwent nondisjunction in gamete production.

32) A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition? A) The woman inherited this tendency from her parents. B) One member of the couple carried a translocation. C) One member of the couple underwent nondisjunction in somatic cell production. D) One member of the couple underwent nondisjunction in gamete production. E) The mother had a chromosomal duplication.

B) Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

32) A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. What would be a potential consequence for a cell in which this happens? Remember that phenylalanine may be encoded by multiple codons. A) None of the proteins in the cell will contain phenylalanine. B) Proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU. C) The cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons. D) The ribosome will skip a codon every time a UUU is encountered.

B) the rules for base pairing between the third base of a codon and tRNA are flexible.

33) There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that A) some tRNAs have anticodons that recognize four or more different codons. B) the rules for base pairing between the third base of a codon and tRNA are flexible. C) many codons are never used, so the tRNAs that recognize them are dispensable. D) the DNA codes for all 61 tRNAs, but some are then destroyed. E) competitive exclusion forces some tRNAs to be destroyed by nucleases.

C) a group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation

33) What is a syndrome? A) a characteristic facial appearance B) a group of traits, all of which must be present if an aneuploidy is to be diagnosed C) a group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation D) a characteristic trait usually given the discoverer's name E) a characteristic that only appears in conjunction with one specific aneuploidy

E) the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

34) Which of the following events in translation is the first to occur in eukaryotes? A) elongation of the polypeptide B) base pairing of activated methionine-tRNA to AUG of the messenger RNA C) binding of the larger ribosomal subunit to smaller ribosomal subunits D) covalent bonding between the first two amino acids E) thD) covalent bonding between the first two amino acids E) the small subunit of the ribosome recognizing and attaching to the 5' cap of mRNA

A) a human chromosome 22 that has had a specific translocation

34) Which of the following is known as a Philadelphia chromosome? A) a human chromosome 22 that has had a specific translocation B) a human chromosome 9 that is found only in one type of cancer C) an animal chromosome found primarily in the mid-Atlantic area of the United States D) an imprinted chromosome that always comes from the mother

A) after an error occurring in anaphase I or anaphase II

35) At what point in cell division is a chromosome lost so that, after fertilization with a normal gamete, the result is an embryo with 45,X? A) after an error occurring in anaphase I or anaphase II B) after an error occurring in anaphase I only C) after an error occurring in anaphase II only D) after an error occurring in prophase I only E) after an error occurring in metaphase II only

B) Monosomy X is the only known viable human monosomy.

36) Which of the following statements correctly describes aneuploid conditions? A) A monosomy is more frequent than a trisomy. B) Monosomy X is the only known viable human monosomy. C) Of all human aneuploidies, only Down syndrome is associated with mental retardation. D) An aneuploidy resulting in the deletion of a chromosome segment is less serious than a duplication.

C) The amino acid methionine will not be covalently bound to the altered tRNA.

37) An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' AC. Which of the following statements correctly describes the most likely result of this change? A) tRNA will not form a cloverleaf. B) The nearby stem end will pair improperly. C) The amino acid methionine will not be covalently bound to the altered tRNA. D) The anticodon will not bind with the mRNA codon. E) The aminoacyl-tRNA synthetase will not be formed.

A) 3'-UCA-5'.

4) A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. The corresponding codon for the mRNA transcribed is A) 3'-UCA-5'. B) 3'-UGA-5'. C) 5'-TCA-3'. D) 3'-ACU-5'. E) either UCA or TCA, depending on wobble in the first base.

B) 8

4) How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? A) 4 B) 8 C) 16 D) 64

C) It is a gene region present on the Y chromosome that triggers male development.

4) Which of the following statements best describes the SRY gene? A) It is a gene present on the X chromosome that triggers female development. B) It is an autosomal gene that is required for the expression of genes on the Y chromosome. C) It is a gene region present on the Y chromosome that triggers male development. D) It is an autosomal gene that is required for the expression of genes on the X chromosome.

D) tortoiseshell females; black males

5) In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male? A) tortoiseshell females; tortoiseshell males B) black females; orange males C) orange females; orange males D) tortoiseshell females; black males E) orange females; black males

A) A gene from an organism can theoretically be expressed by any other organism.

5) The genetic code is essentially the same for all organisms. Based on this information, one can logically assume which of the following statements to be correct? A) A gene from an organism can theoretically be expressed by any other organism. B) All organisms have experienced convergent evolution. C) DNA was the first genetic material. D) The same codons in different organisms translate into the different amino acids. E) Different organisms have different numbers of different types of amino acids.

C) different possible assortment of chromosomes into gametes

5) Which of the following statements describes the major reason that the individual with the genotype AaBbCCDdEE can make many kinds of gametes? A) segregation of maternal and paternal alleles B) crossing over during prophase I C) different possible assortment of chromosomes into gametes D) the tendency for dominant alleles to segregate together

E) XNXn and XNY

6) Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents? A) XNXn and XnY B) XnXn and XNY C) XNXN and XnY D) XNXN and XNY E) XNXn and XNY

A) if UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only)

6) The "universal" genetic code is now known to have exceptions. Evidence for this can be found if which of the following is true? A) if UGA, usually a stop codon, is found to code for an amino acid such as tryptophan (usually coded for by UGG only) B) if one stop codon, such as UGA, is found to have the same effect on translation as another stop codon, such as UAA C) if prokaryotic organisms are able to translate a eukaryotic mRNA and produce the same polypeptide D) if several codons are found to translate to the same amino acid, such as serine

B) to observe whether or not a recessive trait would reappear

6) Why did Mendel continue some of his experiments to the F2 generation? A) to obtain a larger number of offspring on which to base statistics B) to observe whether or not a recessive trait would reappear C) to observe whether or not the dominant trait would reappear D) to distinguish which alleles were segregating

E) 100%

7) Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes? A) 0% B) 25% C) 50% D) 75% E) 100%

D) a triplet in the same reading frame as an upstream AUG

7) Which of the following descriptions of nucleotide triplets best represents a codon? A) a triplet separated spatially from other triplets B) a triplet that has no corresponding amino acid C) a triplet at the opposite end of tRNA from the attachment site of the amino acid D) a triplet in the same reading frame as an upstream AUG E) a sequence in tRNA at the 3' end

A) The law of independent assortment explains the segregation of two or more genes relative to one another.

7) Which of the following statements describes one difference between the law of independent assortment and the law of segregation? A) The law of independent assortment explains the segregation of two or more genes relative to one another. B) The law of segregation explains the segregation of two or more genes relative to one another. C) The law of segregation requires having two or more generations to describe. D) The law of segregation is accounted for by anaphase of mitosis.

B) a male inherits only one allele of the X-linked gene controlling hair color.

8) Normally, only female cats have the tortoiseshell phenotype because A) the males die during embryonic development. B) a male inherits only one allele of the X-linked gene controlling hair color. C) the Y chromosome has a gene blocking orange coloration. D) only males can have Barr bodies.

D) that the parents were both heterozygous for a single trait

8) Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest? A) that the parents were true-breeding for contrasting traits B) that the trait shows incomplete dominance C) that a blending of traits has occurred D) that the parents were both heterozygous for a single trait E) that each offspring has the same alleles for each of two traits

D) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome.

8) Which of the following statements best describes the termination of transcription in prokaryotes? A) RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase. B) RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript. C) RNA polymerase transcribes through an intron, which causes the polymerase to let go of the transcript. D) Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome. E) RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

E) HT

9) A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism? A) tt B) Hh C) HhTt D) T E) HT

B) translocation of the SRY gene to an autosome of a 46,XX individual

9) Sex determination in mammals is due to the SRY gene on the Y chromosome. An abnormality of this region could allow which of the following to have a male phenotype? A) Turner syndrome, 45,X B) translocation of the SRY gene to an autosome of a 46,XX individual C) a person with an extra X chromosome D) a person with one normal and one shortened (deleted) X

C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

9) Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression? A) mRNA, tRNA, and rRNA are transcribed. B) RNA polymerase binds to the promoter. C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end. D) Transcription can begin as soon as translation has begun even a little. E) RNA polymerase requires a primer to elongate the molecule.

C) ww

Figure 11.2 shows a pedigree chart for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. 4) What is the genotype of individual II-5? A) WW B) Ww C) ww D) WW or ww E) ww or Ww

C) 50%

Figure 11.2 shows a pedigree chart for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. 5) What is the likelihood that the offspring of IV-3 and IV-4 will have the trait? A) 0% B) 25% C) 50% D) 75% E) 100%

E) 1

Figure 11.2 shows a pedigree chart for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. 6) What is the probability that individual III-1 is Ww? A) 3/4 B) 1/4 C) 2/4 D) 2/3 E) 1

E) 1, 2, and 3

In a particular plant, leaf color is controlled by gene locus D. Plants with at least one D allele have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in Figure 11.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. 1) Which of the boxes marked 1-4 correspond(s) to plants with dark leaves? A) 1 only B) 1 and 2 C) 2 and 3 D) 4 only E) 1, 2, and 3

D) 2 and 3

In a particular plant, leaf color is controlled by gene locus D. Plants with at least one D allele have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in Figure 11.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. 2) Which of the boxes correspond(s) to plants with a heterozygous genotype? A) 1 only B) 1 and 2 C) 1, 2, and 3 D) 2 and 3 E) 2, 3, and 4

A) 1 and 4 only

In a particular plant, leaf color is controlled by gene locus D. Plants with at least one D allele have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F2 is diagrammed in the Punnett square shown in Figure 11.1, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. 3) Which of the plants will be true-breeding? A) 1 and 4 only B) 2 and 3 only C) 1, 2, 3, and 4 D) 1 only E) 1 and 2 only