SQ topic 14 BIOL1009, SQ Topic 15 BIOL1009, SQ Topic 16 BIOL1009, SQ Topic 17 BIOL1009, SQ Topic 18 BIOL1009, SQ Topic 19 BIOL1009

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short? -1 -1/4 -1/2 -0

-0

A woman is a carrier for red-green color blindness, a sex-linked trait. Her husband is normal (not color-blind) for this trait. What are the chances that their newborn daughter will be red-green color-blind? -75% -0% -25% -100% -50%

-0%

What is the probability that a male will inherit an X-linked recessive allele from his father? -100% -0% -25% -50% -75%

-0%

What is the probability that a male will inherit an X-linked recessive allele from his father? -25% -0% -50% -100% -75%

-0%

In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D 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 the figure below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the plants will be true-breeding? -1 only -1 and 4 only -1 and 2 only -1, 2, 3, and 4 -2 and 3 only

-1 and 4 only

The centimorgan (cM) is a unit named in honor of Thomas Hunt Morgan. To what is it equal? -the distance between a pair of homologous chromosomes -1 nanometer of distance between two genes -1% frequency of recombination between two genes -the recombination frequency between two genes assorting independently -the physical distance between two linked genes

-1% frequency of recombination between two genes

In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D 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 the figure below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the boxes marked 1-4 correspond to plants with dark leaves? -1 and 2 -1 only -4 only -1, 2, and 3 -2 and 3

-1, 2, and 3

Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr x PpRr will have white flowers and wrinkled seeds? -3/4 -1/16 -0 -1/4 -1/2

-1/16

If a heterozygous plant is allowed to self-pollinate, what proportion of the offspring will also be heterozygous? -2/3 -1/4 -1/2 -all of them -1/3

-1/2

Michelle and Keith are apparently normal, but their daughter was born with alkaptonuria, an inherited metabolic disorder. If alkaptonuria is like most other human hereditary disorders, the probability of their next child being born with alkaptonuria is _____. -1/4 -2/3 -0 -1/2

-1/4

An AABbccDdEeFF individual is crossed with an individual with the genotype AaBBCCDdEeff. What is the probability that their offspring will have the genotype AaBBCcddEEFf? -1/4 -1/64 -1/2 -1/16 -1/32

-1/64

In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC? -1/16 -1/4 -1/64 -1/32 -1/8

-1/64

If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce? -1,000,000 -200 -100 -1,000 -10,000

-10,000

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? -25% -0% -100% -50% -75%

-100%

The pedigree below is for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the probability that individual III-1 is Ww? -50% -100% -75% -25% -67%

-100%

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? -38 -24 -12 -31

-12

How many different amino acids could be specified if codons were two nucleotides in length? -4 -16 -2 -8

-16

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1,000 F2 offspring resulted from the cross, approximately how many of them would you expect to have red, terminal flowers? -750 -190 -565 -250 -65

-190

In a particular plant, leaf color is controlled by gene locus D. Plants with at least one allele D 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 the figure below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square. Which of the boxes marked 1-4 correspond to plants with a heterozygous genotype? -1, 2, and 3 -2, 3, and 4 -1 -2 and 3 -1 and 2

-2 and 3

Tom's brother suffers from phenylketonuria (PKU), a recessive disorder. The brothers' parents do not have PKU. What are the chances that Tom, who is normal for this trait, is a carrier of PKU? -1/2 -1/3 -1/4 -2/3 -4/3

-2/3

Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, the progeny plants will be _____. -100% pink -25% white and 75% red -50% pink and 50% red -25% red, 50% pink, and 25% white -100% red

-25% red, 50% pink, and 25% white

How many different amino acids could be specified if codons were four nucleotides in length? -64 -4 -16 -256

-256

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of ATP, GTP, and UTP. How many artificial mRNA 3 nucleotide codons could possibly be made? -3 -9 -27 -6

-27

A particular triplet of bases in the template strand of DNA is 5' GGT 3'. The corresponding codon for the mRNA transcribed is: -3' GGU 5' -3' GGT 5' -3' CCA 5' -3' UGG 5'

-3' CCA 5'

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The anticodon loop of the first tRNA that will complement this mRNA is: -5' ACG 3' -5' GGC 3' -5' UGC 3' -3' GGC 5'

-3' GGC 5'

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is: -3' TCA 5' -3' UGA 5' -3' TGA 5' -3' UCA 5'

-3' UCA 5'

A particular triplet of bases in the template strand of DNA is 5' AAT 3'. The corresponding codon for the mRNA transcribed is: -3' TAA 5' -3' UUA 5' -3' AAT 5' -3' AAU 5'

-3' UUA 5'

Given the locally unwound double strand below, in which direction does the RNA polymerase move? -5' → 3' along the template strand -3' → 5' along the template strand -3' → 5' along the complementary strand -5' → 3' along the complementary strand

-3' → 5' along the template strand

Drosophila (fruit flies) usually have long wings, but mutations in the BTgene can result in bent wings and mutations in the VG gene can result in vestigial wings. If flies that are heterozygous for both the bent wing gene and the vestigial wing gene are mated, what is the probability of offspring with bent wings only? Note that the mutant alleles of both genes are recessive. -3/16 -1/4 -3/8 -1/8 -9/16

-3/16

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. Among the F2 offspring, what is the probability of plants with white axial flowers? -3/16 -9/16 -1/8 -1/16

-3/16

An individual with the genotype AABbCcDD can make how many different kinds of gametes? -8 -2 -32 -16 -4

-4

If a DNA sample were composed of 10% thymine, what would be the percentage of guanine? -40% -90% -10% -80%

-40%

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:3' C C T A G G C T G C A A T C C 5'An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence? -5' G C C T A G G 3' -5' A C G T T A G G 3' -3' G C C T A G G 5' -5' A C G U U A G G 3'

-5' A C G U U A G G 3'

What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below?5' AAGGCTT 3' -5' TTCGGAA 3' -5' AAGCCUU 3' -5' TTCCGAA 3' -5' AAGCCTT 3'

-5' AAGCCTT 3'

The nucleotide sequence of the coding strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' AATTCGGG 3' -5' TTAAGCCC 3' -5' AAUUCGGG 3' -5' CCCGAATT 3' -5' CCCGAAUU 3'

-5' AAUUCGGG 3'

The nucleotide sequence of the coding strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' ATGCGTA 3' -5' TACGCAT 3' -5'UACGCAU 3' -5' AUGCGUA 3' -5' TACGCAT 3'

-5' AUGCGUA 3'

The nucleotide sequence of the coding strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' AATTCGGG 3' -5' CCCGAAUU 3' -5' AAUUCGGG 3' -5' CCCGAATT 3' -5' TTAAGCCC 3'

-5' CCCGAAUU 3'

The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' AATTCGGG 3' -5' TTAAGCCC 3' -5' CCCGAATT 3' -5' CCCGAAUU 3' -5' AAUUCGGG 3'

-5' CCCGAAUU 3'

The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' TTTAAGG 3' -5' CCTTAAA 3' -5' AAATTCC 3' -5' CCUUAAA 3' -5' UUUAAGG 3'

-5' CCUUAAA 3'

What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below?5' GCGAATA 3' -5' CGCTTAT 3' -5' TATTCGC 3'

-5' TATTCGC 3'

What would be the sequence of the DNA molecule made by replication of the DNA molecule shown below?5' TTCCGGA 3' -5' UCCGGAA 3' -5' TCCGGAA 3' -5' AAGGCCT 3' -5' AAGGCCT 3'

-5' TCCGGAA 3'

A peptide has the sequence NH2-phe-pro-lys-gly-phe-pro-COOH. Which of the following sequences in the coding strand of the DNA would code for this peptide? -5' GGG-AAA-TTT-AAA-CCC-ACT-GGG 3' -3' AUG-AAA-GGG-TTT-CCC-AAA-GGG 5' -3' UUU-CCC-AAA-GGG-UUU-CCC 5' -5' TTT-CCC-AAA-GGG-TTT-CCC 3'

-5' TTT-CCC-AAA-GGG-TTT-CCC 3'

The figure below represents a tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which codon on the mRNA strand codes for this amino acid? -5' CUU 3' -5' UUC 3' -5' TTC 3' -5' GAA 3'

-5' UUC 3'

The nucleotide sequence of the coding strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' TTTAAGG 3' -5' CCUUAAA 3' -5' AAATTCC 3' -5' UUUAAGG 3' -5' CCTTAAA 3'

-5' UUUAAGG 3'

Which of the following statements is TRUE? -5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins. -Many prokaryotic genes have "intervening" sequences, or introns, that do not code for proteins. -Many prokaryotic primary mRNA molecules have "intervening" sequences, or introns, that do not code for proteins. -All of these statements are true.

-5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins.

The nucleotide sequence of the template strand of a DNA molecule is shown below. What will be the nucleotide sequence of the RNA molecule made from this segment of DNA? 5' ATGCGTA 3' -5' TACGCAT 3' -5' AUGCGUA 3' -5' TACGCAT 3' -5'UACGCAU 3'

-5'UACGCAU 3'

Hemophilia is a sex-linked disorder. The daughter of a father with hemophilia and a carrier mother has a _____ probability of having hemophilia. -25% -100% -0% -50% -33%

-50%

Human blood groups are governed by three alleles, A, B, and O. A and B are codominant and O is recessive to both. If a woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood? -50% -25% -0% -100% -75%

-50%

In werewolves (hypothetically), pointy ears (P) are dominant over round ears (p). The gene is on the X chromosome. (Sex determination in werewolves is the same as for "other" humans.) A certain female werewolf has pointy ears even though her father had round ears. What percentage of her sons will have round ears if she mates with a werewolf with round ears? -25% -50% -0% -75% -100%

-50%

The pedigree below is for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the likelihood that the progeny of IV-3 and IV-4 will have the trait? -50% -75% -0% -100% -25%

-50%

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? -50% -0% -100% -25% -75%

-50%

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. If true-breeding red long radishes are crossed with true-breeding white oval radishes, which of the following phenotypic ratios would be expected in the F2 generation? -9:3:3:1 -1:1:1:1:1:1 -6:3:3:2:1:1 -9:4:3 -1:1:1:1

-6:3:3:2:1:1

In humans, male-pattern baldness is controlled by an autosomal gene (= a gene that is found on a chromosome other than an X or Y chromosome) that occurs in two allelic forms. Allele Hn determines nonbaldness, and allele Hb determines pattern baldness. In males, because of the presence of testosterone, allele Hb is dominant over Hn. If a man and woman both with genotype HnHb have a son, what is the chance that he will eventually be bald? -33% -0% -25% -50% -75%

-75%

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE? -32 -8 -16 -4

-8

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer. You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many different artificial mRNA 3 nucleotide codons could possibly be made? -4 -16 -8 -3

-8

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? -58% -16% -8% -42%

-8%

In an analysis of the nucleotide composition of DNA, which of the following will be found? -A + C = G + T -A = G and C = T -G + C = T + A -A = C

-A + C = G + T

Between which two genes would you expect the highest frequency of recombination? -W and E -A and G -A and W -E and G -A and E

-A and G

Which of the following cells are very likely to become cancerous? -All of these answers are correct. -A cell with a mutation that causes increased expression of a proto-oncogene and mutations in several tumor-suppressor genes that cause decreased expression of those genes. -A cell with a mutation that causes increased expression of a proto-oncogene. -A cell with a mutation that causes decreased expression of a tumor-suppressor genes.

-A cell with a mutation that causes increased expression of a proto-oncogene and mutations in several tumor-suppressor genes that cause decreased expression of those genes.

What do we mean when we use the terms monohybrid cross and dihybrid cross? -A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. -A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio. -A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one. -A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations.

-A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one.

Which of the following is the best definition of a gene that is being "expressed"? -A gene that is part of chromatin that is open and accessible to transcription factors and RNA polymerase is being expressed. -A gene that is producing lots of RNA is being expressed. -A gene that is producing lots of protein is being expressed. -A gene that is producing its final product (protein or non-coding RNA) in a functional form is being expressed.

-A gene that is producing its final product (protein or non-coding RNA) in a functional form is being expressed.

Which of the following would NOT be considered a gene that is being expressed? -A gene that is producing mRNA, but no protein. -A gene that is producing tRNA, but no protein. -A gene that is producing rRNA, but no protein. -All of these answers are correct.

-A gene that is producing mRNA, but no protein.

Which of the following mutations would make it impossible for a bacterial cell to metabolize lactose? -All of these answers are correct. -A mutation in the operator for the lac operon such that it can no longer bind with lac repressor protein -A mutation in the promoter for the lac operon such that it can no longer bind RNA polymerase -A mutation in the gene encoding the lac repressor protein such that the lac repressor protein can no longer bind to the operator

-A mutation in the promoter for the lac operon such that it can no longer bind RNA polymerase

Which of the following mutations would be likely to increase the chances of a cell becoming cancerous? -All of these answers are correct. -A mutation that decreases the expression of a gene that increases the rate of cell division. -A mutation that increases the expression of a gene that decreases the rate of cell division. -A mutation that decreases the expression of a gene that is needed for efficient repair of DNA mutations.

-A mutation that decreases the expression of a gene that is needed for efficient repair of DNA mutations.

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

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

During translation (polypeptide elongation), charged tRNAs enter the ribosome at the: -T site -A site -E site -P site

-A site

Human blood groups are governed by three alleles, A, B, and O. A and B are codominant and O is recessive to both. A man who has type B blood and a woman who has type A blood could have children of which of the following phenotypes? -A, B, or O -AB or O -A, B, AB, or O -AB only -A or B only

-A, B, AB, or O

A particular triplet of bases in the coding strand of a gene is TTT. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is: -GGG. -UUU. -AAA -TTT.

-AAA

A particular triplet of bases in the template strand of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is: -TTT. -UUA. -AAA. -UUU.

-AAA.

A = big apples;R = red apples; a = small apples; r = yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents? -Aarr and aaRr -AARr and Aarr -AArr and aaRr -AaRr and aarr -AaRr and AaRr

-AArr and aaRr

Four genes (A, B, C, and D) are on the same chromosome. The recombination frequencies are as follows: A-B: 19%; B-C: 14%; A-C: 5%; B-D: 2%; A-D: 21%; C-D: 16%. Based on this information, which sequence of genes is correct? -ADBC -ACBD -ABCD -ABDC

-ACBD

The nitrogenous base adenine is found in all members of which group? -proteins, triglycerides, and testosterone -α glucose, ATP, and DNA -proteins, ATP, and DNA -ATP, RNA, and DNA

-ATP, RNA, and DNA

In a certain plant, the alleles A, B, and C are completely dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as a plant with the genotype _____. -AABBCc -AaBBcc -Aabbcc -None of the listed responses is correct. -aabbcc

-AaBBcc

Different cells may have different combinations of transcriptional activators because: -All of these answers are correct -some cells may produce chemicals that turn off expression of transcriptional activators in nearby cells -cytoplasmic determinants may not be equally distributed within egg cells -during cell division cytoplasmic determinants may not be evenly distributed to the two daughter cells

-All of these answers are correct

The chances that a cell will become cancerous can be increased by: -decreased expression of genes that act in DNA repair -All of these answers are correct. -increased expression of genes that promote cell division -decreased expression of genes that inhibit cell division

-All of these answers are correct.

Transfer RNAs, or tRNAs: -have 3-dimensional shapes that are formed by hydrogen bonding between the nitrogenous bases of some of the ribonucleotides comprising the tRNA -contain an anticodon that base pairs with an appropriate codon on a mRNA molecule -All of these answers are correct. -bind only a specific amino acid

-All of these answers are correct.

Tumor-suppressor genes may encode polypeptides that: -decrease the rate of cell division. -function in DNA repair. -function in cell adhesion. -All of these answers are correct.

-All of these answers are correct.

Which of the following chromatin modifications are possible? -DNA may be modified to make nearby DNA less accessible to the transcription machinery. -All of these answers are correct. Histones may be modified to make nearby DNA more accessible to the transcription machinery. Histones may be modified to make nearby DNA less accessible to the transcription machinery.

-All of these answers are correct.

Why are chimpanzees and (most) humans so different? -Many genes are expressed at different levels in chimpanzees than in humans. -The nucleotide sequences of chimpanzee genes are slightly different than the nucleotide sequences of the corresponding human genes. -The proteins encoded by chimpanzee genes have slightly different amino acid sequences than the corresponding proteins encoded by human genes. -All of these answers are correct.

-All of these answers are correct.

Which of the following statements about how cytoplasmic determinants and induction help control which transcriptional activators are expressed by different cell types is TRUE? -Cytoplasmic determinants are unevenly distributed during cell division, causing the resulting daughter cells to express different combinations of transcriptional activators. -Cytoplasmic determinants are unevenly distributed in egg cells. -All of these statements are true. -Induction causes the cells near the cell producing the inductive agent to express some of the same transcriptional activators.

-All of these statements are true.

Which of the following statements about translation is TRUE? -mRNA molecules are read by the translation machinery in the 5' to 3' direction. -Translation of an mRNA begins at an AUG codon -The 5' and 3' UTRs of an mRNA molecule are not translated. -All of these statements are true.

-All of these statements are true.

Which of the following statements comparing gene expression in skin versus muscle cells is TRUE? -Some genes are only expressed in skin cells. -Some genes are only expressed in muscle cells. -All of these statements are true. -Some genes are expressed at higher levels in skin cells. Other genes are expressed at higher levels in muscle cells.

-All of these statements are true.

Which of the following statements is TRUE? -All of these statements are true. -5' and 3' untranslated regions (UTRs) are parts of exons, but do not code for proteins. -Many prokaryotic genes have "intervening" sequences, or introns, that do not code for proteins. -Many prokaryotic primary mRNA molecules have "intervening" sequences, or introns, that do not code for proteins.

-All of these statements are true.

Which of the following statements about inheritance is TRUE? -Only DNA modifications may be inherited. -Only histone modifications may be inherited. -Only alterations in the actual nucleotide sequence of the DNA may be inherited. -All of these types of modifications may be inherited.

-All of these types of modifications may be inherited.

The chromosome theory of inheritance states that _____. -genes occupy specific positions on chromosomes -chromosomes assort independently during meiosis -All these answers are correct. -homologous chromosomes segregate from each other during meiosis

-All these answers are correct.

Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell? -The repressor protein attaches to the regulator. -The repressor protein and allolactose bind to RNA polymerase. -Allolactose binds to the regulator gene. -Allolactose binds to the repressor protein

-Allolactose binds to the repressor protein

Flies with mutant bicoid genes develop posterior structures at both ends. The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end of a normal (i.e. unmutated) fly embryo, which of the following would occur? -The embryo would grow to an unusually large size. -The embryo would grow extra wings and legs. -Anterior structures would form in both sides of the embryo. -The embryo would probably show no anterior development and die.

-Anterior structures would form in both sides of the embryo.

A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium and grown them for another generation. Which pattern in the figure shown below would you expect if the DNA was replicated in a conservative manner? -B -E -D -C

-B

Why do our chromosomes become shorter as we age? -Because DNA repair enzymes become defective as we age. -All of these answers are correct. -Because DNA polymerases can only add nucleotides to an existing nucleotide chain, an RNA primer is used to initiate DNA synthesis. Once that RNA primer is removed from the end of a linear chromosome, there is no mechanism to completely fill in the missing nucleotides at the end of a linear chromosome. -Because DNA polymerase becomes defective as we age, so that it is not able to fully replicate our DNA within a single replication cycle.

-Because DNA polymerases can only add nucleotides to an existing nucleotide chain, an RNA primer is used to initiate DNA synthesis. Once that RNA primer is removed from the end of a linear chromosome, there is no mechanism to completely fill in the missing nucleotides at the end of a linear chromosome.

Which of the following statements about repressor proteins is FALSE? -Active repressor proteins prevent transcription of certain genes -Binding of a corepressor stabilizes repressor proteins in their inactive shape -Active repressor proteins bind operator sequences -Binding of an inducer prevents a repressor protein from binding its operator sequence

-Binding of a corepressor stabilizes repressor proteins in their inactive shape

Which of the following shows the correct base pairing of deoxyribonucleotides that occurs in nature? -C with T -C with A -C with U -C with G

-C with G

Recombination between linked genes comes about for what reason? -Independent assortment sometimes fails because Mendel had not calculated appropriately. -Crossovers between these genes result in chromosomal exchange. -When genes are linked they always "travel" together at anaphase. -Mutation on one homolog is different from that on the other homolog.

-Crossovers between these genes result in chromosomal exchange.

Which of the following statements regarding cytoplasmic determinants is FALSE? -Cytoplasmic determinants are unevenly distributed in fertilized egg cells. -Cytoplasmic determinants are unevenly distributed in unfertilized egg cells. -The cytoplasmic determinants that are more abundant in a cell help determine which subset of genes is expressed in that cell. -Cytoplasmic determinants are evenly distributed when the zygote divides to produce two daughter cells.

-Cytoplasmic determinants are evenly distributed when the zygote divides to produce two daughter cells.

Which of the following statements regarding cytoplasmic determinants is FALSE? -Cytoplasmic determinants are evenly distributed within egg cells prior to fertilization, and then become unevenly distributed immediately after fertilization. -Cytoplasmic determinants include mRNA molecules. -Cytoplasmic determinants include polypeptides. -Cytoplasmic determinants include molecules that are not polypeptides or mRNAs.

-Cytoplasmic determinants are evenly distributed within egg cells prior to fertilization, and then become unevenly distributed immediately after fertilization.

In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure shown below would be expected after one round of DNA replication in the presence of 14N? -C -D -B -E

-D

Which component is not directly involved in translation? -ribosomes -mRNA -tRNA -DNA

-DNA

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? -DNA in both daughter cells would be radioactive. -Neither of the two daughter cells would be radioactive. -All four bases of the DNA would be radioactive. -One of the daughter cells, but not the other, would have radioactive DNA.

-DNA in both daughter cells would be radioactive.

Which of the following statements is TRUE? -DNA is translated and RNA is transcribed -RNA is translated and proteins are transcribed -RNA is transcribed and proteins are translated -DNA is transcribed and RNA is translated

-DNA is transcribed and RNA is translated

Which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of DNA fragments resulting from DNA replication of one of the two DNA strands? -DNA polymerase III -helicase -DNA polymerase I -primase

-DNA polymerase I

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? -primase -topoisomerase -DNA ligase -DNA polymerase III

-DNA polymerase III

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? -Polymerase can work on only one strand at a time. -DNA ligase works only in the 3' → 5' direction. -The origins of replication occur only at the 5' end. -DNA polymerase can join new nucleotides only to the 3' end of a growing strand.

-DNA polymerase can join new nucleotides only to the 3' end of a growing strand.

A new DNA strand elongates only in the 5' to 3' direction because: -DNA polymerase begins adding nucleotides at the 5' end of the template. -DNA polymerase can only add nucleotides to the free 3' end. -replication must progress toward the replication fork. -the polarity of the DNA molecule prevents addition of nucleotides at the 3' end.

-DNA polymerase can only add nucleotides to the free 3' end.

Why are primases necessary in order for DNA replication to occur? -Primases modify DNA molecules to allow replication of those molecules by DNA polymerases -Primases modify deoxyribonucleotides to allow them to serve as substrates for DNA polymerases -Primases modify DNA polymerases to allow them to carry out their function. -DNA polymerases can not initiate synthesis of new nucleotide chains

-DNA polymerases can not initiate synthesis of new nucleotide chains

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following? -DNA polymerases can only add deoxyribonucleotides to the 5' end of an existing nucleotide chain -the evolution of telomerase enzyme -DNA polymerases can only add deoxyribonucleotides to the 3' end of an existing nucleotide chain -the "no ends" of a circular chromosome

-DNA polymerases can only add deoxyribonucleotides to the 3' end of an existing nucleotide chain

The process by which DNA molecules are copied so that when cells divide each cell can have a complete copy of the DNA is known as: -chromosome duplication -DNA transcription -DNA ligation -DNA replication

-DNA replication

Which of the following correctly shows the flow of information in a cell? -RNA to protein to DNA -RNA to DNA to protein -DNA to RNA to protein -DNA to protein to RNA

-DNA to RNA to protein

Physically, what are different alleles? -None of the listed responses is correct. -Different alleles are different DNA sequences found at the same locus on sister chromatids. -Different alleles are different phenotypes for a particular character. -Different alleles are different particles found in gametes. -Different alleles are different DNA sequences found at the same locus (location) on homologous chromosomes.

-Different alleles are different DNA sequences found at the same locus (location) on homologous chromosomes.

How do different subsets of genes come to be expressed in different cell types? -Each cell type expresses a specific transcriptional activator, which causes alternative splicing of different transcripts. -Different cell types express different combinations of transcriptional activators, which cause alternative splicing of different transcripts. -Different cell types express different combinations of transcriptional activators, which turn on expression of different combinations of genes. -Each cell type expresses a specific transcriptional activator, which turns on expression of a specific combination of genes.

-Different cell types express different combinations of transcriptional activators, which turn on expression of different combinations of genes.

Different genes are expressed in different cells of our bodies because: -Egg cells have an unequal distribution of genes -Epigenetics results in different cells having different genes -Different cells have different combinations of activators -Recombination results in different cells having different genes

-Different cells have different combinations of activators

Why do neural cells have different characteristics than skin cells? -Genes are expressed at higher levels in neural cells, which are very active, than in skin cells, which play primarily a structural role. -Different genes are present in neural than in skin cells. -Neural cells have more copies of some genes and skin cells have more copies of other cells. -Different genes are expressed in neural than in skin cells.

-Different genes are expressed in neural than in skin cells.

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

-Drosophila genes cluster into four distinct groups of linked genes.

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. Which of the samples shown in the figure below shows the density distribution of DNA you would expect in this experiment? -D -C -E -B

-E

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already. Where does tRNA #2 move to after this bonding of lysine to the polypeptide? E site A site exit tunnel P site

-E site

What is meant by the statement that "the genetic code is not ambiguous"? -Each amino acid is specified by just one codon. -All of these answers are correct. -Compared with DNA, RNA has ribose instead of deoxyribose and uracil instead of thymine, preventing mixing up of DNA and RNA -Each codon specifies just one amino acid.

-Each codon specifies just one amino acid.

Queen Victoria was a carrier of a recessive sex-linked allele for hemophilia. Which of the following possibilities could explain the presence of the hemophilia allele in her genotype? -Either her mother was homozygous dominant or her father had hemophilia. -Either her mother was a carrier or her father had hemophilia. -Both her mother and her father had hemophilia. -none of these answers is correct -Either her mother was a carrier or her father had a dominant allele

-Either her mother was a carrier or her father had hemophilia.

What are the coding segments of a stretch of eukaryotic DNA called? -Transcriptons -Introns -Replicons -Exons

-Exons

Which of the following statements about RNA processing is FALSE? -Ribozymes may function in RNA splicing. -Exons are cut out before mRNA leaves the nucleus. -RNA splicing can be catalyzed by spliceosomes. -Nucleotides may be added at both ends of the RNA.

-Exons are cut out before mRNA leaves the nucleus.

Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16? -Chromosome 21 is a sex chromosome, and 3 and 16 are not. -Down syndrome is not more common, just more serious. -There are probably more genes on chromosome 21 than on the others. -Extra copies of the other chromosomes are probably fatal to the developing embryo. -Nondisjunction of chromosomes 3 and 16 probably occurs much less frequently.

-Extra copies of the other chromosomes are probably fatal to the developing embryo.

A particular triplet of bases in the template strand of DNA is GGG. The anticodon on the tRNA that binds the mRNA codon is: -UUU. -CCC. -GGG. -UUA.

-GGG.

What is the difference between "genotype" and "phenotype"? -Genotype refers to individuals that are haploid. Phenotype refers to individuals that are diploid. -Genotype refers to which genes, or which alleles of a particular gene, are carried by an individual. Phenotype refers to the traits exhibited by an individual. -Genotype refers to individuals resulting from a monohybrid cross, whereas phenotype refers to individuals resulting from a dihybrid cross. -Genotype refers to alleles that exhibit complete dominance, whereas phenotype refers to alleles that exhibit incomplete dominance.

-Genotype refers to which genes, or which alleles of a particular gene, are carried by an individual. Phenotype refers to the traits exhibited by an individual.

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? -HhTt -Hh -tt -HT

-HT

If a mother is heterozygous for a recessive sex-linked trait and her husband has the dominant allele, which one of the following is true about the probabilities for their children? -Half of their sons will have the recessive trait. -All of their daughters will be heterozygous. -None of their sons will have the recessive trait. -All of their sons will have the recessive trait. -No answer text provided.

-Half of their sons will have the recessive trait.

A woman is red-green color-blind. What can we conclude, if anything, about her father? -He is red-green color-blind. -We have too little information to tell. -He has two Y chromosomes. -There is a 50% probability that he has normal vision. -none of these answers is correct

-He is red-green color-blind.

Which of the following statements about bacterial repressor proteins is FALSE? -Repressor proteins are often allosteric proteins -Corepressors help repressor proteins bind operators. -Active repressor proteins bind to operators. -High levels of inducers stabilize repressor proteins in their active state.

-High levels of inducers stabilize repressor proteins in their active state.

A man who can roll his tongue and a woman who cannot roll her tongue have a son who can roll his tongue (R = can roll tongue; r = can't roll tongue). The son is curious about whether his father is homozygous or heterozygous for the tongue-rolling trait. Which of the following facts would allow him to know? -The son's own daughter cannot roll her tongue. -The son's sister is a tongue roller. -The son submits his own blood sample to a local genotyping lab, and they establish that he is heterozygous for the trait. -His paternal grandfather and his paternal grandmother can both roll their tongues. -His father's mother cannot roll her tongue.

-His father's mother cannot roll her tongue.

During certain types of cell division in Drosophila, studies have shown that there is phosphorylation of an amino acid in the tails of histones of gametes. A mutation in flies that interferes with this process results in sterility. Which of the following is the most likely hypothesis? -All proteins in the cell must be phosphorylated. -Histone tail phosphorylation prohibits chromosome condensation. -Any mutation during oogenesis results in sterility. -These oocytes have no histones.

-Histone tail phosphorylation prohibits chromosome condensation.

Which of the following statements about histones is FALSE? -Histones help package DNA -Histones help transport mRNA molecules out of the nucleus -Histones are an important component of chromatin -Histones are composed of amino acids

-Histones help transport mRNA molecules out of the nucleus

Will the chromosomes you pass onto your children be shorter than your chromosomes? -Hopefully not, because telomerase will restore the telomeres in your germline cells (the cells that produce egg or sperm cells) to approximately their original length. -Yes, because DNA repair enzymes do not function properly in germline cells (the cells that produce egg or sperm cells). -Yes, because DNA polymerase is not able to fully replicate the ends of chromosomes. -No, because DNA repair enzymes will fill in any missing gaps at the ends of your chromosomes.

-Hopefully not, because telomerase will restore the telomeres in your germline cells (the cells that produce egg or sperm cells) to approximately their original length.

What kind of chemical bond is found between paired bases of the DNA double helix? -Hydrogen -Phosphate -Ionic -Covalent

-Hydrogen

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

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

What happens to the short RNA "primers" that primase synthesizes and that are extended by DNA polymerase III during DNA replication? -In E. coli, DNA polymerase I removes the RNA primers and fills in the resulting gaps with deoxyribonucleotides -DNA ligases join the RNA primers to DNA fragments to create a single, long nucleotide chain -DNA repair enzymes chemically modify the ribonucleotides so that they are converted to deoxyribonucleotides -The RNA primers are unwound by helicases.

-In E. coli, DNA polymerase I removes the RNA primers and fills in the resulting gaps with deoxyribonucleotides

What is the function of the release factor: -It supplies a source of energy for termination of translation. -It releases the amino acid from its tRNA to allow the amino acid to form a peptide bond. -It separates tRNA in the A site from the growing polypeptide. -It binds to the stop codon in the A site in place of a tRNA.

-It binds to the stop codon in the A site in place of a tRNA.

There is a mutation in the lac repressor gene that results in production of an altered lac repressor protein known as a "super-repressor" because it represses the lac operon permanently. Which of these would characterize such a mutant? -It cannot bind to the operator. -It makes molecules that bind to one another. -It cannot bind to the inducer. -It cannot make a functional repressor.

-It cannot bind to the inducer.

Which of the following statements describes the eukaryotic chromosome? -The number of genes on each chromosome is different in different cell types of an organism. -The structure of the chromosome is determined by the nucleotide sequence of its DNA. -It is composed of DNA alone. -It consists of a single linear molecule of double-stranded DNA plus proteins.

-It consists of a single linear molecule of double-stranded DNA plus proteins.

Which of the following statements about a codon is FALSE? -It consists of three nucleotides. -It extends from one end of a tRNA molecule. -It may code for the same amino acid as another codon. -It never codes for more than one amino acid.

-It extends from one end of a tRNA molecule.

Which of the following is characteristic of the product of the p53 gene? -It is a transcriptional activator for other genes. -It is a proto-oncogene. -It speeds up cell division. -It allows cells to pass on mutations due to DNA damage. PreviousNext

-It is a transcriptional activator for other genes.

Which of the following statements about the DNA in one of your brain cells is certainly TRUE? -The majority of genes are likely to be transcribed. -Many genes are grouped into operon-like clusters. -It is the same as the DNA in one of your heart cells. -Most genes lie immediately downstream of an operator sequence.

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

Which of the following statements about the DNA in one of your brain cells is true? -Many genes are grouped into operon-like clusters. -It is the same as the DNA in one of your heart cells. -Most of the DNA codes for protein. -The majority of genes are likely to be transcribed.

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

What is the role of DNA ligase during DNA replication? -It unwinds the parental double helix. -It joins DNA fragments together. -It synthesizes RNA nucleotides to make a primer. -It catalyzes the lengthening of telomeres.

-It joins DNA fragments together.

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century? -Natural selection acts on certain chromosome arrays rather than on genes. -Individuals inherit particular chromosomes attached to genes. -No more than a single pair of chromosomes can be found in a healthy normal cell. -Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis. -Homologous chromosomes give rise to some genes and crossover chromosomes to other genes.

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

Which of the following statements about the genetic code is TRUE? -All of these answers are correct. -Mitochondrial genes use a slightly different genetic code than nuclear genes. -The nuclear genes of every species on earth uses exactly the same genetic code. -Chloroplast genes use a slightly different genetic code that nuclear genes.

-Mitochondrial genes use a slightly different genetic code than nuclear genes.

What is meant by the statement that "the genetic code is redundant"? -Most tRNA molecules can bind a few different amino acids. -The anticodon on a tRNA molecule can bind several codons that are similar in sequence. -All of these answers are correct. -Most amino acids are specified by more than one codon.

-Most amino acids are specified by more than one codon.

Which of the following statements regarding transcriptional activators is TRUE? -Transcriptional activators aid in transcript stability. -Most genes are regulated by only a single transcriptional activator. -Transcriptional activators act in transcript processing. -Most genes are regulated by several different transcriptional activators

-Most genes are regulated by several different transcriptional activators

Transfer RNAs, or tRNAs: -are important components of ribosomes -None of these answers is correct. -form 3-dimensional shapes as a result of ionic bonds between different parts of the molecule. -are translated to form short polypeptides that are part of ribosomes.

-None of these answers is correct.

Human blood groups are governed by three alleles, A, B, and O. A and B are codominant and O is recessive to both. Which of the following matings cannot produce a child with blood type O? The letters refer to blood types (phenotypes). -None of the listed responses is correct. -O x O -A x B -A x A -O x AB

-O x AB

Why are there concerns about using increased telomerase activity to slow down the aging process? -All of these answers are correct. -One concern is that increasing telomerase activity could increase joint problems. -One concern is that increasing telomerase activity could increase cancer rates. -One concern is that increasing telomerase activity could increase diabetes rates.

-One concern is that increasing telomerase activity could increase cancer rates.

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties? -The traits blended together during fertilization. -One phenotype was completely dominant over another. -No genes interacted to produce the parental phenotype. -Each allele affected phenotypic expression.

-One phenotype was completely dominant over another.

Which of the following statements most accurately describes the components of an operon? -Operons have promoters, which are DNA sequences where RNA polymerase binds; operators, which are DNA sequences where translational repressors bind; and structural genes that typically code for proteins that function together in a particular process. -Operons have promoters, which are DNA sequences where RNA polymerase binds; operators, which are DNA sequences where transcriptional repressors bind; and structural genes that typically code for proteins that function together in a particular process. -Operons have promoters, which are DNA sequences where inducers bind; operators, which are DNA sequences where translational repressors bind; and structural genes that typically code for proteins that function together in a particular process. -Operons have promoters, which are DNA sequences where inducers bind; operators, which are DNA sequences where repressors bind; and structural genes that typically code for proteins that function together in a particular process.

-Operons have promoters, which are DNA sequences where RNA polymerase binds; operators, which are DNA sequences where transcriptional repressors bind; and structural genes that typically code for proteins that function together in a particular process.

_____ is usually less severe than _____, and _____ species have been observed in plants, fish, amphibians, and even mammals. -Aneuploidy ... polyploidy ... aneuploid -Trisomy ... monosomy ... trisomic -Polyploidy ... aneuploidy ... polyploid -Monosomy ... trisomy ... monosomic -Nondisjunction ... disjunction ... nondisjunctional

-Polyploidy ... aneuploidy ... polyploid

Which of the following is NOT a major difference between transcription in prokaryotes versus eukaryotes? -Prokaryotic mRNAs are made and translated in the same subcellular compartment; eukaryotic mRNAs are made and translated in different subcellular compartments -Prokaryotic mRNAs do not have introns; eukaryotic mRNAs often have introns -Prokaryotic mRNAs do not have polyA tails; eukaryotic mRNAs do have polyA tails -Prokaryotic mRNA molecules are synthesized by RNA polymerase catalyzing the formation of phosphodiester bonds between ribonucleotides that are base paired with the DNA template strand; eukaryotic mRNA molecules are synthesized by RNA polymerase catalyzing the formation of phosphodiester bonds between ribonucleotides that are base paired with the DNA coding strand

-Prokaryotic mRNA molecules are synthesized by RNA polymerase catalyzing the formation of phosphodiester bonds between ribonucleotides that are base paired with the DNA template strand; eukaryotic mRNA molecules are synthesized by RNA polymerase catalyzing the formation of phosphodiester bonds between ribonucleotides that are base paired with the DNA coding strand

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells? -Proto-oncogenes normally help regulate cell division. -Cells produce proto-oncogenes as they age. -Proto-oncogenes are genetic "junk." -Proto-oncogenes are mutant versions of normal genes.

-Proto-oncogenes normally help regulate cell division.

For a repressible operon to be transcribed, which of the following must occur? -RNA polymerase must bind to the promoter, and the repressor must be inactive. -RNA polymerase cannot be present, and the repressor must be inactive. -RNA polymerase must not occupy the promoter, and the repressor must be inactive. -RNA polymerase and the active repressor must be present.

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

Which of the following statements best describes the termination of transcription in prokaryotes? -RNA polymerase transcribes through an intron, and the snRNPs cause the polymerase to let go of the transcript. -RNA polymerase transcribes through the polyadenylation (polyA) signal, causing proteins to associate with the transcript and cut it free from the polymerase. -RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript. -RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA.

-RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

Two genetically identical fruit flies (Drosophila) are exposed to very different environmental conditions. If you studied the polypeptides present in both flies, what would you expect to find? -Some polypeptides are far more active in one of the fruit flies than in the other one. -Some of the polypeptides in one of the fruit flies exhibit minor variations in amino acid sequence compared to the amino acid sequences of the corresponding polypeptides produced by the other fly. -Some of the primary polypeptides produced by one of the flies have undergone alternative splicing by proteasomes to form slightly different mature polypeptides. -All of these answers are correct.

-Some polypeptides are far more active in one of the fruit flies than in the other one.

X-linked genes differ from Y-linked genes in which of the following ways? -Sons and daughters have equal probabilities in inheriting a recessive allele of an X-linked gene from their mother, but only sons can inherit rare Y-linked genetic disorders from their father. -Though most X-linked genes determine sex, Y-linked genes control for characters unrelated to sex. -Only X-linked genes are technically sex-linked because Y-linked genes affect characteristics unrelated to sex. -Sons and daughters can inherit alleles of X-linked genes from fathers proportionally but only sons inherit alleles of Y-linked genes from their fathers. -Although the X and Y chromosomes carry genes that determine sexual characteristics, there are not corresponding regions of homology for genes located on each chromosome.

-Sons and daughters have equal probabilities in inheriting a recessive allele of an X-linked gene from their mother, but only sons can inherit rare Y-linked genetic disorders from their father.

Which of the following shows the correct base pairing of deoxyribonucleotides that occurs in nature? -T with C -T with U -T with A -T with G

-T with A

Why do some scientists feel that telomerase might be used to slow the aging process? -There is no real evidence; the idea that telomerase could be used to help reduce aging is based solely on theoretical arguments. -Telomere extension in mice and worms allowed them to live to be approximately 100 years old -Teleomere extension in humans has reversed some signs of aging. -Telomere extension in mice and worms has reversed some signs of aging.

-Telomere extension in mice and worms has reversed some signs of aging.

What is meant by the description "antiparallel" regarding the strands that make up DNA? -The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. -One strand is positively charged and the other is negatively charged. -The twisting nature of DNA creates nonparallel strands. -One strand contains only purines and the other contains only pyrimidines.

-The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

A geneticist introduces a transgene into yeast cells and isolates five independent cell lines in which the transgene has integrated into the yeast genome. In four of the lines, the transgene is expressed strongly, but in the fifth there is no expression at all. Which of the following is a likely explanation for the lack of transgene expression in the fifth cell line? -The 5th transgene integrated into a region of the genome where the chromatin is relatively accessible. -The host cell lacks the enzymes necessary to express the transgene. -The 5th transgene integrated into a region of the genome where the chromatin is relatively inaccessible. -The 5th transgene is undergoing alternative splicing.

-The 5th transgene integrated into a region of the genome where the chromatin is relatively inaccessible.

The order in which chromatin packing occurs is as follows: -The DNA wraps around histones, forming nucleosomes; the chromatin forms loops by attaching to scaffold proteins; the histones within each nucleosome interact with adjacent nucleosomes and with the DNA between nucleosomes to form a 30-nm fiber -The histones within nucleosomes interact with adjacent nucleosomes and with the DNA between nucleosomes to form a 30-nm fiber; the chromatin forms loops by attaching to scaffold proteins, forming a 300-nm fiber; the DNA wraps around histones, forming nucleosomes -The chromatin forms loops by attaching to scaffold proteins; the histones within nucleosomes interact with adjacent nucleosomes and with the DNA between nucleosomes to form a 30-nm fiber; the DNA wraps around histones, forming nucleosomes -The DNA wraps around histones, forming nucleosomes; the histones within each nucleosome interact with adjacent nucleosomes and with the DNA between nucleosomes to form a 30-nm fiber; the chromatin forms loops by attaching to scaffold proteins, forming a 300-nm fiber

-The DNA wraps around histones, forming nucleosomes; the histones within each nucleosome interact with adjacent nucleosomes and with the DNA between nucleosomes to form a 30-nm fiber; the chromatin forms loops by attaching to scaffold proteins, forming a 300-nm fiber

Which of the following best describes the function of the XIST gene in X chromosome inactivation? -The XIST gene codes for an enzyme that methylates DNA on the X chromosome being inactivated. -Together with other proteins, the product of the XIST gene binds to histones and induces supercoiling of the DNA in one of the X chromosomes, thus inactivating it. -Protein encoded by the XIST gene coats one of the X chromosomes, causing that X chromosome to form an inactive Barr body. -The XIST gene on the X chromosome to be inactivated is expressed to produce multiple RNA transcripts that bind to that chromosome and effectively cover it up, thereby generating a Barr body.

-The XIST gene on the X chromosome to be inactivated is expressed to produce multiple RNA transcripts that bind to that chromosome and effectively cover it up, thereby generating a Barr body.

Which of the following statements is true of linkage? -Crossing over occurs during prophase II of meiosis. -All of the traits that Mendel studied-seed color, pod shape, flower color, and others-are due to genes linked on the same chromosome. -The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. -The observed frequency of recombination of two genes that are far apart from each other has a maximum value of 100%. -Linked genes are found on different chromosomes.

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

What is "chromatin"? -Origins of DNA replication -Special proteins that function as chromosomal attachment sites for the mitotic spindle apparatus. -The combination of DNA and proteins that forms chromosomes -The ends of linear chromosomes

-The combination of DNA and proteins that forms chromosomes

In comparing DNA replication with transcription, which of the following is true only of DNA replication? -The entire template molecule is represented in the product. -It uses RNA polymerase. -It makes a new molecule from its 5' end to its 3' end. -The process occurs in the nucleus of a eukaryotic cell.

-The entire template molecule is represented in the product.

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

-The frequency of crossing over varies along the length of the chromosome.

A red-eyed female fly was crossed with a white-eyed male fly. All the F1 offspring had red eyes. Two of these red-eyed F1 generation flies were crossed 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? -The gene involved is on the Y chromosome. -Other male-specific factors influence eye color in flies. -The gene involved is on an autosome, but only in males. -The gene involved is on the X chromosome. -Other female-specific factors influence eye color in flies.

-The gene involved is on the X chromosome.

Cystic fibrosis, which is usually lethal before the age of reproduction, is a homozygous recessive trait. Why do cases continue to arise, even though people with the disease rarely live to reproduce? -New mutations continually introduce this harmful condition into the population. -Mosquitoes can transfer the disease from person to person. -People continue to make inappropriate lifestyle choices. -None of the listed responses is correct. -The harmful allele "hides" within heterozygous individuals, and one-fourth of the offspring of two heterozygotes would be afflicted.

-The harmful allele "hides" within heterozygous individuals, and one-fourth of the offspring of two heterozygotes would be afflicted.

If an experimenter moves the repressor gene (lac I) for the lac operon, along with its promoter, to a position some several thousand base pairs away from its normal position in the lac operon, which will you expect to occur? -The repressor will no longer be made. -The repressor will no longer bind to the inducer. -The lac operon will function normally. -The lac operon will be expressed continuously.

-The lac operon will function normally.

Which of the following statements comparing regulation of the lac and trp operons is TRUE? -The lac repressor protein is stabilized in its active shape by binding its inducer (allolactose), whereas the trp repressor protein is stabilized in its inactive shape by binding its corepressor (tryptophan). -The lac repressor protein is stabilized in its inactive shape by binding its inducer (allolactose), whereas the trp repressor protein is stabilized in its active shape by binding its corepressor (tryptophan). -The lac repressor protein is stabilized in its inactive shape by binding its corepressor (allolactose), whereas the trp repressor protein is stabilized in its active shape by binding its inducer (tryptophan). -The lac repressor protein is stabilized in its active shape by binding its corepressor (allolactose), whereas the trp repressor protein is stabilized in its inactive shape by binding its inducer (tryptophan).

-The lac repressor protein is stabilized in its inactive shape by binding its inducer (allolactose), whereas the trp repressor protein is stabilized in its active shape by binding its corepressor (tryptophan).

You are studying the polypeptides produced by a particular human gene, and notice that about half of the polypeptides have a molecular mass of 200 kDa and the other half have a molecular mass of 150 kDa. One of your hypotheses for why this gene might produce proteins of different molecular masses might be: -The transcripts produced by the gene are more heavily translated in some cells than in others. -The primary transcripts encoded by the gene undergo alternative splicing and the different mature mRNAs that result encode proteins with different numbers of exons and thus different molecular masses. -The gene is more heavily transcribed in some cells than in others. -All of these hypotheses are reasonable.

-The primary transcripts encoded by the gene undergo alternative splicing and the different mature mRNAs that result encode proteins with different numbers of exons and thus different molecular masses.

Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous? -There is not enough information to answer the question. -The ratio of tall offspring to short offspring is 3:1. -The ratio of tall offspring to short offspring is 1:1. -All of the offspring are tall.

-The ratio of tall offspring to short offspring is 1:1.

An experimenter moves the operator for the lactose operon to the far end of the operon (past all of the structural genes in the lactose operon). Which of the following would likely occur when the cell is exposed to lactose? -The inducer will no longer bind to the repressor. -The operon will never be transcribed. -The repressor will no longer bind to the operator. -The structural genes will be transcribed continuously.

-The structural genes will be transcribed continuously.

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

-The two genes are closely linked on the same chromosome.

What does a frequency of recombination of 50% indicate? -Abnormal meiosis has occurred. -The two genes are likely to be located on different chromosomes. -All of the offspring have combinations of traits that match one of the two parents. -The genes are located on sex chromosomes. -Independent assortment is hindered

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

When the genome of a particular species is said to include 20,000 protein-coding regions, what does this imply? -Each gene codes for one protein. -There are also genes for RNAs other than mRNA. -Any other regions are "junk" DNA. -There are 20,000 genes.

-There are also genes for RNAs other than mRNA.

In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes, dATP, dCTP, dGTP, and radioactively labeled dTTP (3H thymidine) for several minutes and then switched to nonradioactive medium. It is then viewed by electron microscopy and autoradiography. The figure shown below represents the results.The grains in the figure represent radioactive material within the replicating eye.Which of the following is the most likely interpretation? -Thymidine is only being added where the DNA strands are furthest apart. -Replication proceeds in one direction only. -Thymidine is only added at the very beginning of replication. -There are two replication forks going in opposite directions.

-There are two replication forks going in opposite directions.

What is the reason that linked genes are inherited together? -Genes align that way during metaphase I of meiosis. -They are located close together on the same chromosome. -The number of genes in a cell is greater than the number of chromosomes. -Alleles are paired together during meiosis. -Chromosomes are unbreakable.

-They are located close together on the same chromosome.

Which of the following statements describes proto-oncogenes? -Their normal function is to suppress tumor growth. -They are underexpressed in cancer cells. -They can code for proteins associated with cell growth and/or division. -They are produced by mutations induced by carcinogenic substances.

-They can code for proteins associated with cell growth and/or division.

Duchenne muscular dystrophy is caused by a sex-linked recessive allele. Its victims are almost invariably boys, who usually die before the age of 20. Why is this disorder almost never seen in girls? -A sex-linked allele cannot be passed from mother to daughter. -The allele is carried on the Y chromosome. -To express an X-linked recessive allele, a female must have two copies of the allele. -Sex-linked traits are never seen in girls. -Nondisjunction occurs in males but not in females.

-To express an X-linked recessive allele, a female must have two copies of the allele.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? -There is considerable genetic variation in garden peas. -Genes are composed of DNA. -Traits are inherited in discrete units, and are not the results of "blending." -Recessive genes occur more frequently in the F1 generation than do dominant ones.

-Traits are inherited in discrete units, and are not the results of "blending."

Which of the following statements is true about protein synthesis in prokaryotes? -Extensive RNA processing is required before prokaryotic transcripts can be translated. -Translation can begin while transcription is still in progress. -Prokaryotic cells have complicated mechanisms for targeting proteins to the appropriate cellular organelles. -Unlike eukaryotes, prokaryotes require no initiation or elongation factors.

-Translation can begin while transcription is still in progress.

A particular triplet of bases in the coding strand of a gene is AAA. If an mRNA is made from this gene, the anticodon on the tRNA that will bind the codon on the mRNA is: -TTT. -AAA. -UUU. -UUA.

-UUU.

A particular triplet of bases in the template strand of DNA is TTT. The anticodon on the tRNA that binds the mRNA codon is: -TTT. -UUU. -UUA. -AAA.

-UUU.

Which of the following statements about the trp operon is TRUE? -When trp repressor protein binds tryptophan it is stabilized in its inactive shape, preventing transcription of the genes of the trp operon from occurring. -When trp repressor protein binds tryptophan, it is stabilized in its inactive shape, allowing transcription of the genes of the trp operon to proceed. -When trp repressor protein binds tryptophan, it is stabilized in its active shape, preventing transcription of the genes of the trp operon from occurring. -When trp repressor protein binds tryptophan, it is stabilized in its active shape, allowing transcription of the genes of the trp operon to proceed.

-When trp repressor protein binds tryptophan, it is stabilized in its active shape, preventing transcription of the genes of the trp operon from occurring.

A genetic defect in humans results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way: A woman with this defect typically has small patches of skin with sweat glands and other patches without sweat glands. In women, the pattern of sweat-gland distribution can best be explained by _____. -an operon -X chromosome inactivation -RNA splicing -a homeobox -a mutation

-X chromosome inactivation

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? -XcXc and XCY -XcXc and XcY -XCXC and XcY -XCXc and XCY -XCXC and XCY

-XCXc and XCY

In humans, which chromosome combinations normally determine whether an individual is biologically female or male? -XY individuals are biologically female, XX individuals are biologically male -Diploid individuals are biologically female, haploid individuals are biologically male -XX individuals are biologically female, XY individuals are biologically male -XX individuals are biologically female, YY individuals are biologically male

-XX individuals are biologically female, XY individuals are biologically male

A colleague of yours is asked to develop a strain of mutant mice that will be extremely likely to develop cancer so that these mice can be used to study cancer treatments. Your colleague causes a mutation in a mouse that causes the mouse to express a proto-oncogene at greatly increased levels. However, your colleague is disappointed to find the mouse does not have cancer and asks your advice on what he should do next. What should you tell your colleague? -You remind your colleague that a mutation that increases the expression of a single proto-oncogene is generally not sufficient to cause cells to become cancerous. He should also cause some mutations in the mouse's DNA that cause increased expression of some of the mouse's tumor-suppressor genes. -You remind your colleague that a mutation that increases the expression of a single proto-oncogene is generally not sufficient to cause cells to become cancerous. He should also cause some mutations in the mouse's DNA that cause decreased expression of some of the mouse's tumor-suppressor genes. -You tell your colleague that they made a mistake by increasing expression of the proto-oncogene and that they should instead cause a mutation in a mouse that causes decreased expression of the proto-oncogene. In addition, you remind your colleague that a mutation that decreases the expression of a single proto-oncogene is generally not sufficient to cause cells to become cancerous. They should also cause some mutations in the mouse's DNA that cause increased expression of some of the mouse's tumor-suppressor genes. -You tell your colleague that they made a mistake by increasing expression of the proto-oncogene and that they should instead cause a mutation in a mouse that causes decreased expression of the proto-oncogene.

-You remind your colleague that a mutation that increases the expression of a single proto-oncogene is generally not sufficient to cause cells to become cancerous. He should also cause some mutations in the mouse's DNA that cause decreased expression of some of the mouse's tumor-suppressor genes.

A friend of yours is asked to conduct experiments to determine why a particular polypeptide is present in much higher levels in heart cells than in neural cells. She carefully measures the levels of mature mRNA from the gene that encodes the polypeptide and determines that heart and neural cells contain the same levels of the mature mRNA. She next measures the rate at which the mature mRNA that encodes the polypeptide is translated and finds that rates of translation of that mRNA are the same in heart and neural cells. Your friend now has no idea why the polypeptide is present at higher levels in heart versus neural cells and asks your advice on what to do next. What advice should you give her? -You should advise her to give up as research is hopeless and she will make more money as an investment banker anyways. -You should remind her that the levels of a polypeptide are determined not only by how frequently the mRNA encoding that polypeptide is translated, but also by the rate at which the polypeptide is degraded. So, she should consider conducting some experiments to determine whether the polypeptide is degraded more rapidly in neural cells than in heart cells. -You should remind her that histone acetylation may also affect protein levels. -You should remind her that differences in the rates at which primary RNA molecules are processed can affect protein levels.

-You should remind her that the levels of a polypeptide are determined not only by how frequently the mRNA encoding that polypeptide is translated, but also by the rate at which the polypeptide is degraded. So, she should consider conducting some experiments to determine whether the polypeptide is degraded more rapidly in neural cells than in heart cells.

Which of the following will happen to your chromosomes as you become older? -Your chromosomes will become shorter. -The frequency of mutations will become smaller as DNA repair enzymes do their job. -Your DNA will accumulate segments of RNA that are left over from the work of primase. -All of these answers are correct.

-Your chromosomes will become shorter.

Of the following, which is the most current description of a gene? -a DNA sequence that is expressed to form a functional product: either RNA or polypeptide -a discrete unit of hereditary information that consists of a sequence of amino acids -a DNA subunit that codes for a single complete protein -a particular type of mRNA molecule

-a DNA sequence that is expressed to form a functional product: either RNA or polypeptide

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the LEAST serious effect on the polypeptide product? -a deletion of three nucleotides -a deletion of two nucleotides -a deletion of one nucleotide -a deletion of four nucleotides

-a deletion of three nucleotides

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the MOST serious effect on the polypeptide product? -an insertion of a codon -a deletion of a codon -a deletion of 3 consecutive nucleotides -a deletion of two nucleotides

-a deletion of two nucleotides

An oncogene is formed by: -alternative splicing of a proto-oncogene. -a mutation in a proto-oncogene that causes increased expression of the proto-oncogene. -a mutation in a proto-oncogene that causes decreased expression of the proto-oncogene. -unequal distribution of a proto-oncogene.

-a mutation in a proto-oncogene that causes increased expression of the proto-oncogene.

Which of the following is most likely to have a small protein called ubiquitin attached to it? -an mRNA that is leaving the nucleus to be translated -a protein involved in glycine biosynthesis in a cell with lots of glycine -a cell surface protein that requires transport from the ER -a regulatory protein that requires sugar residues to be attached

-a protein involved in glycine biosynthesis in a cell with lots of glycine

Which of the following would you expect of a eukaryote lacking telomerase? -a high probability of somatic cells becoming cancerous -increased rates of DNA mutations -inability to repair thymine dimers -a reduction in chromosome length in gametes

-a reduction in chromosome length in gametes

When a ribosome reaches the end of the coding region of an mRNA molecule, so that a stop codon is in the A site of the ribosome, -a special termination tRNA binds the stop codon at the A site and the polypeptide is freed from the tRNA in the E site -a release factor binds the stop codon at the A site and the polypeptide is freed from the tRNA in the E site -a special termination tRNA binds the stop codon at the A site and the polypeptide is freed from the tRNA in the P site -a release factor binds the stop codon at the A site and the polypeptide is freed from the tRNA in the P site

-a release factor binds the stop codon at the A site and the polypeptide is freed from the tRNA in the P site

A chromosome is: -a single long DNA molecule plus the short RNA molecules with which that DNA molecule is complexed -the group of proteins that bind to DNA molecules -a single long DNA molecule plus the proteins with which that DNA molecule is complexed -a single long DNA molecule

-a single long DNA molecule plus the proteins with which that DNA molecule is complexed

Which of the following mutations would be most likely to have a harmful effect on an organism? -a single nucleotide insertion near the end of the coding sequence -a single nucleotide insertion downstream of, and close to, the start of the coding sequence -a deletion of three nucleotides near the middle of a gene -a single nucleotide deletion in the middle of an intron

-a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Drosophila (fruit flies) usually have long wings, but mutations in the BTgene can result in bent wings and mutations in the VG gene can result in vestigial wings. If a homozygous bent wing fly is mated with a homozygous vestigial wing fly, which of the following offspring would you expect? Note that flies that have one wild-type allele and one mutant allele of the BTgene are represented by +bt, and flies that have one wild-type allele and one mutant allele of the VG gene are represented by +vg. -all +bt +vg heterozygotes -all homozygous + flies -1/2 bent and vestigial to 1/2 normal -3/4 bent to 1/4 vestigial ratio -1/2 bent and 1/2 vestigial flies

-all +bt +vg heterozygotes

If you cross a plant that is homozygous for the recessive allele of a trait with a plant that is homozygous for the dominant allele of the same trait, the F1 generation will differ from the F2 in that _____. -all of the F1 will show the dominant phenotype, but only three-fourths of the F2 will -none of the F1 will show the dominant phenotype, but one-half of the F2 will -all of the F1 will show the dominant phenotype, and all of the F2 will show the recessive phenotype -all of the F1 will show the dominant phenotype, whereas only half of the F2 will -one-half of the F1 will show the dominant phenotype, and three-fourths of the F2 will

-all of the F1 will show the dominant phenotype, but only three-fourths of the F2 will

If an organism that is homozygous dominant is crossed with a heterozygote for that trait, the offspring will be _____. -all homozygous recessive -present in a 9:3:3:1 ratio -all homozygous dominant -1/4 of the recessive phenotype -all of the dominant phenotype

-all of the dominant phenotype

When a DNA molecule is replicated, -the DNA strands in the original molecule are known as the "parental" DNA strands -replication generally occurs by a "semi-conservative" mechanism -the DNA strands that are made by copying the parental DNA strands are known as the "daughter" strands -all of these answers are correct

-all of these answers are correct

Which of the following are needed for the initiation of transcription? -RNA polymerase -all of these answers are correct -transcription factors -a promoter sequence

-all of these answers are correct

Which of the following are needed for the initiation of transcription? -all of these answers are correct -a promoter sequence -RNA polymerase -transcription factors

-all of these answers are correct

Which of the following statements about pre-mRNAs (primary mRNAs) is correct? -Primary mRNAs may contain both exons and introns -all of these answers are correct -Introns are removed from primary mRNAs by splicing -PolyA tails are added to primary mRNAs

-all of these answers are correct

Which of the following statements is TRUE? -all of these answers are correct -5' UTRs are part of exons -3' UTRs are part of exons -coding regions are part of exons

-all of these answers are correct

Which of the following would result in genetic variation by way of new combinations of alleles? -the exchange of alleles between homologous chromosomes during meiosis I -random fertilization increasing the number of possible allele combinations in an individual -independent alignment of homologous chromosomes during meiosis I -all of these answers are correct

-all of these answers are correct

Which of the following is very important in regulating gene expression? -controlling the rate at which mRNAs are translated -controlling the rate at which genes are transcribed -all of these answers are correct. -controlling mRNA stability

-all of these answers are correct.

Which of the following statements regarding DNA polymerases is TRUE? -DNA polymerases can only add nucleotides to the 3' end of a nucleotide chain -DNA polymerases can add nucleotides to the 3' end of an RNA molecule -DNA polymerases can NOT initiate synthesis of a new deoxyribonucleotide chain -all of these statements are true

-all of these statements are true

Which of the following statements regarding primases is TRUE? -all of these statements are true -Primases catalyze the formation of an RNA molecule -Primases can initiate synthesis of a new nucleotide chain -Primases add nucleotides to the 3' end of a nucleotide or nucleotide chain

-all of these statements are true

Alternative versions of a gene are known as: -dihybrids -phenotypes -alt-genes -alleles

-alleles

Translation of mRNA: -almost always begins at an AUG codon, which specifies alanine -almost always begins at an AUG codon, which specifies glycine -almost always begins at an AUG codon, which specifies methionine -almost always begins at an AUG codon, which specifies valine

-almost always begins at an AUG codon, which specifies methionine

A single gene is known to code for three different, but related, proteins. This could be due to which of the following? -premature mRNA degradation -use of different enhancers -alternative RNA splicing -differential transport

-alternative RNA splicing

Which of the following are NOT components of a nucleotide? -a nitrogenous base -an "R" group -a phosphate group -a sugar

-an "R" group

The enzyme that catalyzes the formation of a covalent bond between a tRNA and a specific amino acid is: -tRNA peptidase -amino tRNA peptidase -tRNA peptide synthase -an aminoacyl tRNA synthetase

-an aminoacyl tRNA synthetase

When the ribosome reaches a stop codon on the mRNA, no corresponding tRNA enters the A site. If the translation reaction were to be experimentally stopped at this point, which of the following would you be able to isolate? -an assembled ribosome with a separated polypeptide -an assembled ribosome with a polypeptide attached to the tRNA in the P site -separated ribosomal subunits with a polypeptide attached to the tRNA -separated ribosomal subunits, a polypeptide, and free tRNA

-an assembled ribosome with a polypeptide attached to the tRNA in the P site

A "Barr body" is: -an active Y chromosome -an active X chromosome -an inactive Y chromosome -an inactive X chromosome

-an inactive X chromosome

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the LEAST serious effect on the polypeptide product? -an insertion of two nucleotides -an insertion of one nucleotide -an insertion of three nucleotides -an insertion of four nucleotides

-an insertion of three nucleotides

A mutation that increases the expression of a gene that promotes cell division may cause that gene to become: -All of these answers are correct. -a proto-oncogene -an oncogene -a tumor-suppressor gene

-an oncogene

Cells that have a number of chromosomes different from the normal number for their species are known as _____. -polyploid -aneuploid -trisomy -nanoploid -diploid

-aneuploid

In Klinefelter syndrome, individuals are phenotypically male, but they have reduced sperm production and may have some breast development in adolescence. The cells of Klinefelter individuals have two X chromosomes and one Y (they are XXY instead of XY). This occurs because of what meiotic error? -aneuploidy -duplication -translocation -polyploidy -monosomy

-aneuploidy

When a person has Down syndrome, he or she has an extra chromosome 21. Therefore, Down syndrome is a kind of _____ and results from _____. -aneuploidy ... nondisjunction of chromosome 21 during meiosis I -none of these answers is correct -replication error ... an extra cycle of DNA synthesis during the S phase -genomic imprint ... excessive methylation of either the paternal or maternal chromosome 21 -polyploidy ... occurrence of meiosis without cytokinesis

-aneuploidy ... nondisjunction of chromosome 21 during meiosis I

Ribosomal RNAs, or rRNAs: -contain anticodons that base pair with codons on mRNA molecules -have polyA tails -are not translated to form proteins -serve as templates for the formation of ribosomal proteins

-are not translated to form proteins

In a series of mapping experiments, the recombination frequencies for four different linked genes of Drosophila were determined as shown in the figure below. What is the order of these genes on a chromosome map? -vg-cn-b-rb -b-rb-cn-vg -vg-b-rb-cn -rb-cn-vg-b -cn-rb-b-vg

-b-rb-cn-vg

The formation of hydrogen bonds between complementary nucleotides is known as: -complementation -base pairing -homologous joining -DNA binding

-base pairing

During translation, the role of release factors is to: -bind rRNAs, allowing their release from the ribosome -bind tRNAs, allowing their release from the ribosome -release amino acids from charged tRNAs -bind the mRNA stop codon in the A site of the ribosome, causing release of the completed polypeptide

-bind the mRNA stop codon in the A site of the ribosome, causing release of the completed polypeptide

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the: -bonding of the anticodon to the codon. -bonding of the anticodon to the codon and the attachment of amino acids to tRNAs. -attachment of amino acids to tRNAs. -binding of ribosomes to mRNA.

-bonding of the anticodon to the codon and the attachment

Proto-oncogenes: -All of these answers are correct. -are normal genes found in all human cells -can become oncogenes when they become mutated in such a way that their expression level increases. -encode polypeptides that help increase rates of cell division.

-can become oncogenes when they become mutated in such a way that their expression level increases.

Tumor-suppressor genes: -can encode proteins that promote DNA repair or cell-cell adhesion. -are cancer-causing genes introduced into cells by viruses. -are frequently overexpressed in cancerous cells. -often encode proteins that stimulate the cell cycle.

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

Altering expression of a single transcriptional activator: -will never cause the organism to die because most genes are regulated by multiple transcriptional activators. -will always cause the organism to die, because it won't be able express critical genes. -will have little effect on organismal development because most genes are regulated by multiple transcriptional activators. -can have a huge effect on organismal development, even causing one body part to develop in place of another.

-can have a huge effect on organismal development, even causing one body part to develop in place of another.

An individual who is heterozygous at a given genetic locus for a recessively inherited disorder is known as a: -dominant -carrier -recessive -codominant

-carrier

Epigenetic inheritance includes inheritance of: -mutations that result in deletion of several nucleotides and of changes in both DNA and histone modifications -changes in both DNA and histone modifications -mutations that result in deletion of several nucleotides and of changes in histone modifications -mutations that result in deletion of several nucleotides and of changes in DNA modifications

-changes in both DNA and histone modifications

A red bull is crossed with a white cow and all of the offspring are roan, an intermediate color that is caused by the presence of both red and white hairs. This is an example of genes that are _____. -completely dominant -nonhomologous -polygenic -epistatic -codominant

-codominant

If the phenotypes of both alleles are exhibited in the heterozygote, the alleles must be what type of alleles? -dominant alleles -recessive alleles -incompletely dominant alleles -codominant alleles

-codominant alleles

The group of three nucleotides that specifies an amino acid is known as: -codon -tRNA -translation unit -transcription unit

-codon

The pairs of nucleotides that interact to join together two DNA strands are known as: -partner nucleotides -homologous nucleotides -complementary nucleotides -homozygous nucleotides

-complementary nucleotides

The anticodon of a particular tRNA molecule is: -complementary to the corresponding mRNA codon. -complementary to the corresponding triplet in rRNA. -the part of the tRNA that bonds to a specific amino acid. -changeable, depending on the amino acid that attaches to the tRNA.

-complementary to the corresponding mRNA codon.

Homologous pairs of chromosomes often _____. -are paired up in the G2phase of the cell cycle -differ in length -carry different genes for different traits -are not both present in diploid somatic cells -contain different alleles

-contain different alleles

Operons: -are found only in eukaryotes. -are generally involved in lactose metabolism. -contain structural genes, promoters and an operator region. -are composed of many genes on different chromosomes.

-contain structural genes, promoters and an operator region.

What would occur if the repressor of an inducible operon were mutated so it could not bind the operator? -irreversible binding of the repressor to the promoter -reduced transcription of the operon's genes -continuous transcription of the operon's genes -buildup of a substrate for the pathway controlled by the operon

-continuous transcription of the operon's genes

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

-continuous transcription of the structural gene controlled by that regulator.

A mutation that inactivates the function of a repressor protein involved in the regulation of a bacterial operon would result in: -continuous transcription of the structural genes in the operon. -irreversible binding of the repressor protein to the mRNA. -inactivation of the RNA polymerase. -inhibition of transcription of the structural genes in the operon.

-continuous transcription of the structural genes in the operon.

Which of the following is NOT a common mechanism of gene regulation? -control of mRNA export from the nucleus -control of mRNA degradation -control of protein degradation -control of gene duplication

-control of gene duplication

A lack of which molecule would result in the cell's inability to "turn off" genes? -operon -corepressor -promoter -inducer

-corepressor

Certain molecules (polypeptides, mRNAs and other molecules) become unevenly distributed in egg cells and, consequently, in the two daughter cells formed by division of an egg cell. Some of these molecules then lead to expression of different sets of transcriptional activators in the daughter cells. These molecules are known as: -molecular determinants -morphological determinants -cytoplasmic determinants -nuclear determinants

-cytoplasmic determinants

The reaction used to join together nucleotides to form a nucleotide chain is known as a: -dehydration reaction -DNA catalysis reaction -phosphodiesterase reaction -hydrolysis reaction

-dehydration reaction

The elongation of the leading strand during DNA synthesis: -progresses away from the replication fork. -occurs in the 3' → 5' direction. -depends on the action of DNA polymerase. -produces Okazaki fragments.

-depends on the action of DNA polymerase.

Phenotype: -describes the position of the centromeres on different chromosomes. -describes an individual's observable traits. -describes the genes (or alleles of genes) carried by a particular individual. -describes the lengths of different chromosomes.

-describes an individual's observable traits.

Alleles are: -genes that segregate together -the phenotypic characters expressed by different genes -different versions of a gene -genes that do not segregate together

-different versions of a gene

The fact that plants can be cloned from many different types of cells demonstrates that: -differentiation does not occur in plants. -differentiated cells retain all the genes of the zygote. -the differentiated state is normally very unstable. -genes are lost during differentiation.

-differentiated cells retain all the genes of the zygote.

According to the "semi-conservative" model of DNA replication, after a double-stranded DNA molecule is replicated: -one of the two resulting double-stranded DNA molecules will consist of two "daughter" DNA strands and the other double-stranded DNA molecule will consist of two "parental" DNA strands -each of the two resulting double-stranded DNA molecules will consist of one "daughter" and one "parental" DNA strand -each DNA strand of one of the two resulting double-stranded DNA molecules will consist partly of "daughter" DNA and partly of "parental" DNA and each DNA strand of the other double-stranded DNA molecule will consist solely of "daughter" DNA -each DNA strand of each of the two resulting double-stranded DNA molecules will consist partly of "daughter" DNA and partly of "parental" DNA

-each of the two resulting double-stranded DNA molecules will consist of one "daughter" and one "parental" DNA strand

Inheritance of traits not directly involving nucleotide sequences is known as: -epigenetic inheritance -DNA inheritance -non-nuclear inheritance -tRNA inheritance

-epigenetic inheritance

The HXK gene is transcribed, resulting in production of HXK mRNA molecules. The total number of HXK mRNA molecules that are present in a cell at any given moment is: -more dependent on the rate at which the HXK mRNA molecules are made (transcribed) than on the rate at which they are broken down -equally dependent on the rate at which the HXK mRNA molecules are made (transcribed) and the rate at which they are broken down -mostly dependent on how active RNA polymerase is. -less dependent on the rate at which the HXK mRNA molecules are made (transcribed) than on the rate at which they are broken down

-equally dependent on the rate at which the HXK mRNA molecules are made (transcribed) and the rate at which they are broken down

The SIS8 gene is transcribed to form SIS8 mRNAs. The SIS8 mRNAs are then translated to form SIS8 polypeptides. The total number of SIS8 polypeptides present in a cell at a given moment is: -less dependent on the rate at which the SIS8 polypeptides are made (translated) than on the rate at which they are broken down -equally dependent on the rate at which the SIS8 polypeptides are made (translated) and the rate at which they are broken down -mostly dependent on how active the ribosomes are. -more dependent on the rate at which the SIS8 polypeptides are made (translated) than on the rate at which they are broken down

-equally dependent on the rate at which the SIS8 polypeptides are made (translated) and the rate at which they are broken down

Which of the following types of RNA molecules have polyA tails? -eukaryotic and prokaryotic mRNA molecules -eukaryotic mRNA molecules -eukaryotic mRNA and tRNA molecules -eukaryotic mRNA, tRNA and rRNA molecules

-eukaryotic mRNA molecules

Muscle cells differ from nerve cells mainly because they: -have unique ribosomes. -contain different genes. -use different genetic codes. -express different genes.

-express different genes.

Muscle cells differ from nerve cells mainly because they: -use different genetic codes. -contain different genes. -express different genes. -have unique ribosomes.

-express different genes.

Inactivation of one of the two X chromosomes in females occurs early during embryo development. A random X chromosome is inactivated in each cell present during the period during which inactivation occurs. As a consequence: -½ the cells in a female embryo become unviable, and need to be replaced by mitosis of neighboring cells. -all of these answers are correct -different cells in a female embryo contain different X chromosomes -females are a mosaic of two types of cell, those with the active X chromosome derived from the father and those with the active X chromosome derived from the mother.

-females are a mosaic of two types of cell, those with the active X chromosome derived from the father and those with the active X chromosome derived from the mother.

A "sex-linked" gene is a: -gene that determines how attractive an individual is to the other sex -gene that determines whether an individual is biologically male or female -gene that determines an individual's sex drive -gene found on either the X or Y chromosomes

-gene found on either the X or Y chromosomes

In colorectal cancer, several genes must be mutated in order to make a cell a cancer cell. Which of the following kinds of genes would you expect to be mutated? -the genes of the bacteria that are abundant in the colon -genes coding for enzymes that act in the colon -genes that are especially susceptible to mutation -genes involved in control of the cell cycle

-genes involved in control of the cell cycle

The recombination frequency between two gene loci is _____. -equal to the size of the chromosome -dependent on the sex of the parent -greater as the distance between the two loci decreases -greater as the distance between the two loci increases -dependent on whether dominant or recessive alleles are carried at the two loci

-greater as the distance between the two loci increases

In a nucleosome, the DNA is wrapped around: -ribosomes. -satellite DNA. -histones. -polymerase molecules.

-histones.

If an organism has two identical alleles of a particular gene, the organism is: -dominant for that gene -homozygous for that gene -incompletely dominant for that gene -heterozygous for that gene

-homozygous for that gene

Gene expression in eukaryotes is NOT regulated by: -how efficiently proteins are transported to their correct cellular destinations -how efficiently trans-inducer molecules are transported to the correct part of the nucleus -how efficiently RNA molecules are processed -mRNA stability

-how efficiently trans-inducer molecules are transported to the correct part of the nucleus

The two strands of a double-stranded DNA molecule are held together by: -polar covalent bonds -nonpolar covalent bonds -ionic bonds -hydrogen bonds

-hydrogen bonds

The two strands of a double-stranded DNA molecule are held together by: -ionic bonds between phosphate groups and nitrogenous bases -hydrogen bonds between sugar groups -hydrogen bonds between phosphate groups -hydrogen bonds between complementary nitrogenous bases

-hydrogen bonds between complementary nitrogenous bases

If a plant variety is true-breeding for a dominant trait, then _____. -if the plant were allowed to self-pollinate, the dominant and recessive traits would consistently appear in a 3:1 ratio among the progeny -if the plant were crossed with a heterozygote, one-half of the progeny would show the dominant trait, and one-half would show the recessive trait -if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait -the variety is unable to mutate -the plant is heterozygous for the trait

-if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait

In a double-stranded DNA molecule, the two DNA strands base pair in such a way that the 5' end of one DNA strand base pairs with the 3' end of the other DNA strand. The two DNA strands are said to be: -homologously paired -covalently bound -in an antiparallel arrangement -in an Okazaki arrangement

-in an antiparallel arrangement

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. The flower color trait in radishes is an example of which of the following? -incomplete dominance -full dominance -sex linkage -a multiple allelic system -codominance

-incomplete dominance

If the phenotype of a heterozygote is intermediate between the phenotypes of individuals homozygous for either allele, the alleles carried by that heterozygote must be what type of alleles? -recessive alleles -incompletely dominant alleles -codominant alleles -dominant alleles

-incompletely dominant alleles

Transcriptional activators: -increase affinity of tRNAs for the mRNA -bind operators, preventing binding of repressors -increase the affinity of RNA polymerase for the promoter -increase affinity of ribosomes for the mRNA

-increase the affinity of RNA polymerase for the promoter

Increasing the affinity of RNA polymerase for the promoter of a particular gene will: -increase the rate at which that gene is transcribed. -increase the rate at which that gene is translated. -decrease the rate at which that gene is transcribed. -decrease the rate at which that gene is translated.

-increase the rate at which that gene is transcribed.

Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation? -cAMP -inducer -transcription factor -RNA polymerase

-inducer

Which of the following, when taken up by the cell, binds to the repressor protein so that the repressor protein no longer binds to the operator? -ubiquitin -inducer -promoter -corepressor

-inducer

A single aminoacyl tRNA synthetase can typically recognize: -just one amino acid and just one tRNA -multiple amino acids, but just one tRNA -just one amino acid, but several tRNAs -multiple amino acids and multiple tRNAs

-just one amino acid, but several tRNAs

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent: -Okazaki fragments and RNA primers. -leading strands and Okazaki fragments. -lagging strands and Okazaki fragments. -leading strands and RNA primers.

-leading strands and Okazaki fragments.

Which of the following enzymes covalently connects segments of DNA? -DNA polymerase I -DNA polymerase III -ligase -primase

-ligase

"Linked genes" are: -genes involved in holding together homologous pairs of chromosomes during metaphase I of meiosis I -located near each other on the same chromosome and thus tend to be inherited together -involved in similar metabolic processes -genes involved in holding together sister chromatids during meiosis I

-located near each other on the same chromosome and thus tend to be inherited together

Males are more often affected by sex-linked traits than females because: -males only have one copy of the X chromosome. -male hormones such as testosterone often alter the effects of mutations on the X chromosome. -mutations on the Y chromosome often worsen the effects of X-linked mutations. -female hormones such as estrogen often compensate for the effects of mutations on the X chromosome. -X chromosomes in males generally have more mutations than X chromosomes in females.

-males only have one copy of the X chromosome.

A 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: -many nucleotides are needed to code for each amino acid. -many noncoding stretches of nucleotides are present in mRNA. -there are termination exons near the beginning of mRNA. -there is redundancy and ambiguity in the genetic code.

-many noncoding stretches of nucleotides are present in mRNA.

Because the frequency of crossing over is not uniform along the length of a chromosome, _____. -the centiMorgan is an unreliable unit of measurement, and is rarely used today -pairs of homologous chromosomes contain small but significant differences in gene order -map units do not necessarily correlate to physical distances along the chromosome -the recombination frequency between two genes cannot be used to calculate the number of map units separating them -recombination frequency cannot be used to determine the number of centiMorgans separating two genes

-map units do not necessarily correlate to physical distances along the chromosome

Changes in chromatin structure: -are important in regulating gene expression in prokaryotes -may include modifications to histones, but not to DNA -may be inherited -may include modifications to DNA, but not to histones

-may be inherited

In eukaryotes, transcriptional activators: -may bind specific DNA sequences associated with genes and decrease the affinity of RNA polymerase for the promoters for those genes. -may bind specific DNA sequences associated with genes and increase the affinity of ribosomes for the promoters for those genes. -may bind specific DNA sequences associated with genes and decrease the affinity of ribosomes for the promoters for those genes. -may bind specific DNA sequences associated with genes and increase the affinity of RNA polymerase for the promoters for those genes.

-may bind specific DNA sequences associated with genes and increase the affinity of RNA polymerase for the promoters for those genes.

What amino acid sequence will be generated, based on the following mRNA codon sequence? 5' AUG-UCU-UCG-UUA-UCC-UUG 3' -met-arg-glu-arg-glu-arg -met-ser-leu-ser-leu-ser -met-glu-arg-arg-glu-leu -met-ser-ser-leu-ser-leu

-met-ser-ser-leu-ser-leu

Which of the following are NOT found in operons? -Operators -miRNAs -Promoters -Genes

-miRNAs

Women (and all female mammals) have one active X chromosome per cell instead of two. What causes this? -activation of the XIST gene on the Y chromosome, which then inactivates one of the X chromosomes -crossover between the XIST gene on one X chromosome and a related gene on an autosome -inactivation of the XIST gene on the X chromosome derived from the male parent -the removal of methyl (CH3) groups from the X chromosome that will remain active -modification of the XIST gene so that it is active only on one X chromosome, which then becomes inactive

-modification of the XIST gene so that it is active only on one X chromosome, which then becomes inactive

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____. -sticky chiasmata -nondisjunction -gametic infertility -cellular sterility -meiotic failure

-nondisjunction

Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior (e.g. head) larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene: -leads to programmed cell death. -is transcribed in the early embryo. -normally leads to formation of tail structures. -normally leads to formation of head structures.

-normally leads to formation of head structures.

Which of the following represents the order of increasingly higher levels of organization of chromatin? -nucleosome, 30-nm chromatin fiber, looped domain -30-nm chromatin fiber, nucleosome, looped domain -looped domain, 30-nm chromatin fiber, nucleosome -nucleosome, looped domain, 30-nm chromatin fiber

-nucleosome, 30-nm chromatin fiber, looped domain

DNA polymerases can add deoxyribonucleotides to: -only the 3' end of an existing nucleotide chain -either the 3' or the 5' end of an existing nucleotide chain -only the end of an RNA chain -only the 5' end of an existing nucleotide chain

-only the 3' end of an existing nucleotide chain

A linkage map _____. -orders genes on a chromosome based on recombination frequencies -orders genes on a chromosome based on their location with respect to a stained band -predicts the probability that you will have a male or female child -shows the ordering and exact spacing of genes on a chromosome -can be constructed only for sex chromosome

-orders genes on a chromosome based on recombination frequencies

DNA replication begins are special sites on the parental DNA molecule known as: -Okazaki regions -primase binding sites -DNA polymerase binding sites -origins of replication

-origins of replication

Histones are: -part of nucleosomes -part of DNA replication origins -part of centromeres -part of telomeres

-part of nucleosomes

The observable physical and physiological traits of an organism, which are determined by its genetic makeup, are its: -genotype -codominance -recessiveness -phenotype

-phenotype

The covalent linkages joining together nucleotides in a DNA molecule are known as: -nucleotide linkages -peptide bonds -glycosidic bonds -phosphodiester linkages

-phosphodiester linkages

Which of the following is NOT a typical modification of a eukaryotic primary (or precursor) mRNA? -addition of a 5' cap -addition of a 3' polyA tail -phosphorylation -removal (splicing out) of introns

-phosphorylation

Ribosomes are composed of: -polypeptides and RNAs -polypeptides and lipids -polypeptides, RNAs and carbohydrates -polypeptides and carbohydrates

-polypeptides and RNAs

Which of the following enzymes initiates the synthesis of a new nucleotide chain during DNA replication? -primase -DNA polymerase II -DNA polymerase III -DNA polymerase I

-primase

Which of the following enzymes synthesizes short segments of RNA? -DNA polymerase I -primase -DNA polymerase III -ligase

-primase

A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The charged transfer RNA molecules (with their anticodons shown in the 3' to 5' direction) shown in the table below are available. Two of them can correctly match the mRNA so that a dipeptide can form. The dipeptide that will form will be: -alanine-alanine. -proline-threonine. -cysteine-alanine. -glycine-cysteine.

-proline-threonine.

Histones are: -proteins around which the DNA in chromosomes wrap -proteins that bind solely to centromeres -proteins that bind solely to telomeres -proteins that help unwind DNA prior to DNA replication

-proteins around which the DNA in chromosomes wrap

A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that: -the cell will compensate for the defect by attaching phenylalanine to tRNAs with lysine-specifying anticodons. -proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU. -none of the options will occur; the cell will recognize the error and destroy the tRNA. -none of the proteins in the cell will contain phenylalanine.

-proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant characteristic. If true-breeding red long radishes are crossed with true-breeding white oval radishes, the F1 will be expected to be which of the following? -white and long -red and oval -purple and long -red and long -purple and oval

-purple and long

It is far more common to find human genetic disease caused by _____ alleles than by _____ alleles because _____. -dominant ... recessive ... dominant alleles became dominant because they aid the survival of the organism carrying them -recessive ... dominant ... harmful recessive alleles can survive in the heterozygote without any selection pressure against them -recessive ... dominant ... even when homozygous, recessive alleles usually do not cause as much damage as dominant alleles -None of the listed responses is correct. -dominant ... recessive ... dominant alleles have an evolutionary advantage over recessive alleles

-recessive ... dominant ... harmful recessive alleles can survive in the heterozygote without any selection pressure against them

An allele whose phenotypic effect is not observed in a heterozygote is a: -recessive allele -codominant allele -incompletely dominant allele -dominant allele

-recessive allele

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? -roan × roan -red × roan -red × white -white × roan

-roan × roan

Which of the following describes the sequence of events that occurs during DNA replication of a double-stranded DNA molecule? -separation of the DNA strands at DNA replication origins, unwinding of the DNA double helix, synthesis of RNA primers, ligation of RNA fragments, synthesis of DNA -separation of the DNA strands at DNA replication origins, unwinding of the DNA double helix, synthesis of DNA, synthesis of RNA primers, ligation of DNA fragments -separation of the DNA strands at DNA replication origins, synthesis of RNA primers, synthesis of DNA, ligation of DNA fragments, unwinding of DNA -separation of the DNA strands at DNA replication origins, unwinding of the DNA double helix, synthesis of RNA primers, synthesis of DNA, ligation of DNA fragments

-separation of the DNA strands at DNA replication origins, unwinding of the DNA double helix, synthesis of RNA primers, synthesis of DNA, ligation of DNA fragments

The DNA molecule is able to carry a vast amount of hereditary information in which of the following? -phosphate-sugar backbones -sequence of bases -complementary pairing of bases -side groups of nitrogenous bases

-sequence of bases

Transcription in eukaryotes requires which of the following in addition to RNA polymerase? -the protein product of the promoter -start and stop codons -several transcription factors (TFs) -aminoacyl synthetase

-several transcription factors (TFs)

In eukaryotic cells, transcription cannot begin until: -the 5' caps are removed from the mRNA. -the DNA introns are removed from the template. -several transcription factors have bound to the promoter. -the two DNA strands have completely separated and exposed the promoter.

-several transcription factors have bound to the promoter.

"Alternative splicing" refers to: -the polycistronic mRNA made by a prokaryotic organism being cut to form different polypeptides. -different sets of chromatin modifications being cut from different genes. -slightly different sets of introns being present in different mature mRNA molecules made from a single gene. -slightly different sets of exons being present in different mature mRNA molecules made from a single gene.

-slightly different sets of exons being present in different mature mRNA molecules made from a single gene.

The final product of an expressed gene can be which of the following? -mRNA, rRNA or polypeptide -tRNA, rRNA or polypeptide -mRNA, tRNA or rRNA -mRNA, tRNA, rRNA or polypeptide

-tRNA, rRNA or polypeptide

The ends of linear chromosomes are known as: -centromeres -telomeres -DNA replication origins -endomeres

-telomeres

The DNA strand to which ribonucleotides hydrogen bond during transcription is known as the: -mRNA strand -transcription strand -template strand -coding strand

-template strand

The sequence of an RNA molecule will be complementary to the sequence of the: -promoter strand from which that RNA molecule was made -transcription strand from which that RNA molecule was made -template strand from which that RNA molecule was made -coding strand from which that RNA molecule was made

-template strand from which that RNA molecule was made

Two plants are crossed, resulting in offspring with a 3:1 ratio for a particular trait. What does this suggest? -that the trait shows incomplete dominance -that the parents were true-breeding for contrasting traits -that a blending of traits has occurred -that the parents were both heterozygous for a single trait

-that the parents were both heterozygous for a single trait

During translation, tRNAs leave the ribosome from: -the E site -the A site -the T site -the P site

-the E site

The progeny of a cross between two individuals of the "parental generation" are known as: -the F1 generation. -dihybrids. -the F2 generation. -heterozygotes.

-the F1 generation.

If a particular operon encodes enzymes for making an essential amino acid and is regulated like the trp operon, then: -the amino acid inactivates the repressor. -the amino acid acts as a corepressor. -the repressor is active in the absence of the amino acid. -the amino acid turns on transcription of the operon.

-the amino acid acts as a corepressor.

Telomeres are: attachment sites for the mitotic spindle apparatus -part of the extracellular matrix -pores in the nuclear membrane that allow for passage of materials --into and out of the nucleus -the ends of linear chromosomes

-the ends of linear chromosomes

Scientists sometimes transfer genes from one species to a different species. What property of the genetic code typically allows these genes to produce a protein of the same amino acid sequence in the new species as they did in the original species? -the genetic code is non-ambiguous -the genetic code is redundant -the genetic code is almost universal -the genetic code exhibits wobble

-the genetic code is almost universal

During translation, -the growing polypeptide chain is transferred from the tRNA in the P ribosome site to the amino acid attached to the tRNA in the A ribosome site. -the growing polypeptide chain is transferred from the tRNA in the E ribosome site to the amino acid attached to the tRNA in the A ribosome site. -the growing polypeptide chain is transferred from the tRNA in the A ribosome site to the amino acid attached to the tRNA in the P ribosome site. -the growing polypeptide chain is transferred from the tRNA in the P ribosome site to the amino acid attached to the tRNA in the E ribosome site.

-the growing polypeptide chain is transferred from the tRNA in the P ribosome site to the amino acid attached to the tRNA in the A ribosome site.

"X inactivation" refers to: -the inactivation of most of the genes on the X chromosome of genetic males -the degradation of the X chromosome by the Y chromosome in genetic males -the inactivation of most of the genes on both X chromosomes in genetic females -the inactivation of most of the genes on one X chromosome in genetic females

-the inactivation of most of the genes on one X chromosome in genetic females

The leading and the lagging strands differ in that: -the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. -the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. -the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. -the leading strand is synthesized at twice the rate of the lagging strand.

-the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

The leading and the lagging strands differ in that: -the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction. -the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. -the leading strand is synthesized at twice the rate of the lagging strand. -the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.

-the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

Wild type refers to _____. -a kind of chromosomal deletion -any mutant genotype -the most extreme mutant phenotype observed in an experiment -the most common phenotype thought to be found in the natural population

-the most common phenotype thought to be found in the natural population

In an X-linked, or sex-linked, trait, it is the contribution of _____ that determines whether a son will display the trait. -the father -the paternal grandfather -the mother -none of these answers is correct -the paternal grandmother

-the mother

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that: -the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. -triphosphate monomers are active in the nucleoside triphosphates, but not in ATP. -the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. -ATP contains three high-energy bonds; the nucleoside triphosphates have two.

-the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

How do the nucleotides used to make RNA molecules differ from those used to make DNA molecules? -the nucleotides used to make RNA molecules have ribose instead of deoxyribose as their sugar and uracil instead of thymine as one of their nitrogenous bases -the nucleotides used to make RNA molecules have ribose instead of deoxyribose as their sugar and two phosphate groups instead of three -the nucleotides used to make RNA molecules have ribose instead of deoxyribose as their sugar and uracil instead of adenine as one of their nitrogenous bases -the nucleotides used to make RNA molecules have deoxyribose instead of ribose as their sugar and uracil instead of thymine as one of their nitrogenous bases

-the nucleotides used to make RNA molecules have ribose instead of deoxyribose as their sugar and uracil instead of thymine as one of their nitrogenous bases

During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site, -the position of the ribosome on the mRNA shifts and a new, charged tRNA enters the entry site of the ribosome -the position of the ribosome on the mRNA shifts and a new, charged tRNA enters the P site of the ribosome -the position of the ribosome on the mRNA shifts and a new, charged tRNA enters the E site of the ribosome -the position of the ribosome on the mRNA shifts and a new, charged tRNA enters the A site of the ribosome

-the position of the ribosome on the mRNA shifts and a new, charged tRNA enters the A site of the ribosome

Cell differentiation always involves: -the transcription of the myoDgene. -the production of tissue-specific proteins, such as muscle actin. -the duplication of certain genes from the genome -the selective loss of certain genes from the genome.

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

Within a cell, the amount of protein made using a given mature mRNA molecule depends partly on: -the number of introns present in the mRNA. -the presence of certain transcription factors. -the degree of DNA methylation. -the rate at which the mRNA is degraded.

-the rate at which the mRNA is degraded.

Which of the following is an example of post-transcriptional control of gene expression? -the addition of methyl groups to cytosine bases of DNA -the folding of DNA to form heterochromatin (densely packed chromatin) -the binding of transcription factors to a promoter -the removal of introns and alternative splicing of exons

-the removal of introns and alternative splicing of exons

During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site, -the ribosome shifts over one nucleotide on the mRNA, such that the codon specifying the next amino acid is now lined up with the P site -the ribosome shifts over one codon on the mRNA, such that the codon specifying the next amino acid is now lined up with the P site -the ribosome shifts over one codon on the mRNA, such that the codon specifying the next amino acid is now lined up with the A site -the ribosome shifts over one nucleotide on the mRNA, such that the codon specifying the next amino acid is now lined up with the A site

-the ribosome shifts over one codon on the mRNA, such that the codon specifying the next amino acid is now lined up with the A site

During translation, after the ribosome breaks the bond between the growing polypeptide chain and the tRNA in the P site and then forms a covalent (peptide) bond between the growing polypeptide chain and the amino acid attached to the tRNA in the A site, -the tRNA that was in the P site is now in the A site and leaves the ribosome -the tRNA that was in the P site is now in the E site and binds another amino acid -the tRNA that was in the P site is now in the E site and leaves the ribosome -the tRNA that was in the P site is now in the A site and binds another amino acid

-the tRNA that was in the P site is now in the E site and leaves the ribosome

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because: -they prevent infection by retroviruses that cause cancer. -they speed up rates of cell division when mutated. -their normal products participate in repair of DNA damage. -they block penetration of breast cells by chemical carcinogens.

-their normal products participate in repair of DNA damage.

What is the function of DNA polymerase III? -to add nucleotides to the 3' end of a growing DNA strand -to seal together the broken ends of DNA strands -to rejoin the two DNA strands (one new and one old) after replication -to unwind the DNA helix during replication

-to add nucleotides to the 3' end of a growing DNA strand

For the DNA molecule shown below, where would the promoter be located? -at the 5' end of the newly made RNA -to the left of the template strand -to the right of the template strand -at the 3' end of the newly made RNA

-to the right of the template strand

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? -orange females; black males -orange females; orange males -tortoiseshell females; tortoiseshell males -black females; orange males -tortoiseshell females; black males

-tortoiseshell females; black males

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

-traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the F1.

The proteins that help RNA polymerase bind the DNA at the promoter site are known as: -RNA primers -transcription initiators -transcription primers -transcription factors

-transcription factors

Which of the following help form a transcription complex at a promoter? -ribosomes and RNA polymerase -primase and RNA polymerase -transcription factors and RNA polymerase -transcription factors and primase

-transcription factors and RNA polymerase

Some genes that encode polypeptides that decrease the rate of cell division are known as: -proto-oncogenes -carcinogen genes -oncogenes -tumor-suppressor genes

-tumor-suppressor genes

Some genes that encode polypeptides that function in DNA repair are known as: -mutagen genes -tumor-suppressor genes -proto-oncogenes -oncogenes

-tumor-suppressor genes

The tryptophan operon is a repressible operon that is: -permanently turned on. -turned off whenever tryptophan is added to the growth medium. -turned on only when tryptophan is present in the growth medium. -turned off only when glucose is present in the growth medium.

-turned off whenever tryptophan is added to the growth medium.

Protein degradation may be mediated by: -ubiquitin binding a protein and preventing it from being degraded by a proteasome. -a proteasome binding a protein and preventing it from being degraded by ubiquitin. -ubiquitin binding a protein and targeting it for degradation by a proteasome. -a proteasome binding a protein and targeting it for degradation by ubiquitin.

-ubiquitin binding a protein and targeting it for degradation by a proteasome.

The pedigree below is for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the genotype of individual II-5? -ww or Ww -WW -ww -WW or ww -Ww

-ww

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? -1/16 -½ -3/16 -3/8 -9/16

-½

Given the parents 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? -1 -1/8 -3/8 -¾ -1/4

-¾

Which of the following statements comparing mRNAs produced by prokaryotes versus eukaryotes is TRUE? -Mature prokaryotic and mature eukaryotic mRNAs often code for multiple polypeptides. -Mature prokaryotic mRNAs often code for multiple polypeptides whereas mature eukaryotic mRNAs typically code for only one polypeptide. -Mature eukaryotic mRNAs often code for multiple polypeptides whereas mature prokaryotic mRNAs typically code for only one polypeptide. -Mature prokaryotic and mature eukaryotic mRNAs typically code for only one polypeptide.

Mature prokaryotic mRNAs often code for multiple polypeptides whereas mature eukaryotic mRNAs typically code for only one polypeptide.

Which of the following statements about the lac operon is TRUE? -When lac repressor protein binds allolactose, it is stabilized in its inactive shape, preventing transcription of the genes of the lac operon from occurring. -When lac repressor protein binds allolactose, it is stabilized in its active shape, preventing transcription of the genes of the lac operon from occurring. -When lac repressor protein binds allolactose, it is stabilized in its active shape, allowing transcription of the genes of the lac operon to proceed. -When lac repressor protein binds allolactose, it is stabilized in its inactive shape, allowing transcription of the genes of the lac operon to proceed.

When lac repressor protein binds allolactose, it is stabilized in its inactive shape, allowing transcription of the genes of the lac operon to proceed.

Genotype: -describes whether a particular species produces gametes that are haploid or diploid. -describes the position of the centromeres on different chromosomes. -describes the genes (or alleles of genes) carried by a particular individual. -describes the lengths of different chromosomes.

describes the genes (or alleles of genes) carried by a particular individual.

An allele that is fully expressed in the phenotype of a heterozygote is a: -codominant allele -incompletely dominant allele -dominant allele -recessive allele

dominant allele

Approximately what percentage of human genes that have more than on exon undergo alternative splicing? ~50% ~ 10% ~ 1% ~ 95%

~ 95%