Exam 4 Mastering

2n=6 1. Meiosis occurs normally 2. Nondisjunction of one chromosome pair in meiosis I 3. nondisjunction of all 3 chromosome pairs in meiosis I 4. Nondisjunction of one chromosome in one daughter cell in meiosis II 5. Nondisjunction of all 3 chromosomes in one daughter cell in meiosis II

3, 2 or 4, 0 or 6, 2 3 or 4, 0 3 or 6

place the steps involved in the process of bacterial transformation 1. One strand of donor DNA is degraded 2. Transformed DNA recombines with the recipient cell chromosome 3. Donor cell lyses, releasing pieces of its chromosome into the environment 4. Transformed DNA pairs with homologous region on the recipient cell chromosome 5. Donor cell DNA bind to a receptor site on the recipient cell

3, 5, 1, 4, 2

A Robertsonian translocation is considered non-reciprocal because _______. A. The smaller of the two reciprocal products of translocated chromosomes is lost B. for every viable gamete formed, there are two inviable gametes formed C. trisomies of chromosome 21 are viable, whereas monosomies of the same chromosome are not D. an uneven number of gametes is produced in each meiosis

A

Bacteriophage T4 can adsorb to its host because of binding sites in its tail fibers that recognize areas of the E. coli cell wall. A. True B. False

A

Duplications and deletions can be detected during meiosis by the presence of extrachromosomal loops that do not pair properly with their homolog. A. True B. False

A

Genes X, Y, and Z are linked. Crossover gametes between genes X and Y are observed with a frequency of 25%, and crossover gametes between genes Y and Z are observed with a frequency of 5%. What is the expected frequency of double crossover gametes among these genes? A. 1.25% b. 30% c. 5% d. 50%

A

How many chromosomes would be found in an allopolyploid plant if its parents had diploid numbers of 4 and 6 respectively? A. Diploid number of 5 B. Haploid number of 12 C. Haploid number of 5 D. Diploid number of 10

A

If two genes on the same chromosome exhibit complete linkage, what is the expected F2 phenotypic ratio from a selfed heterozygote with the genotype a + b + ⁄⁄ ab? A. 3:1 B. 1:1:1:1 C. 1:1 D. 9:3:3:1

A

Two genes that are separated by 10 map units show a recombination percentage of 10%. A. True B. False

A

What is the first order of chromatin packing? A. Coiling around nucleosomes B. Formation of a 300‑nm fiber C. Looping of 300‑nm fibers D. Formation of a solenoid

A

What makes up the protein component of a nucleosome core? A. Two tetramers of histone proteins B. Eight different histone proteins C. One tetramer of histone proteins D. Histone H1 protein

A

Which histone helps stabilize the solenoid structure? a. H1 b.H2A c. H2B d. H3 e. H4

A

Which of the following accurately describes a possible meiotic nondisjunction event? A. Homologs fail to separate during meiosis I. B. Meiosis fails to proceed to completion. C. Fusion of gametes results in trisomy. D. Sister chromatids fail to separate during meiosis I.

A

A cross between a tetraploid and a diploid member of the same species will produce offspring that can undergo sexual reproduction. A. True B. False

B

All of the following could result from meiosis in a pericentric inversion heterozygote in which a single crossover occurred within the inversion loop except a _______. A. chromosome with some deleted regions B. chromosome with two centromeres C. completely normal chromosome D. chromosome with some duplicated regions

B

Crossing over during prophase I of meiosis occurs between alleles on sister chromatids A. True B. False

B

Dark G bands that appear along chromosomes contain ... A. centromeres. B. heterochromatic regions. C. euchromatic regions. D. telomeres.

B

In an interrupted mating experiment, the purpose of plating cells on a selective medium is _______. A. to eliminate all recipient cells B. to ensure that only recombinant genotypes are recovered C. to ensure that conjugation has been completed D. to determine the genes present in the Hfr

B

In order to create the possibility of generating a trisomy, nondisjunction must occur during meiosis II. A. True B. False

B

Inversion loops do NOT form during meiosis in paracentric inversion heterozygotes. A. True B. False

B

The second order of chromatin packing occurs when nucleosomes coil together to form a fiber that is 300 nm in diameter. A. true B. False

B

To construct a mapping cross of linked genes, it is important that the genotypes of some of the gametes produced by the heterozygote can be deduced by examining the phenotypes of the progeny. A. True B. False

B

True or false? A bacterial strain that is pro + thi + leu − met − will grow on minimal media plus leucine and thiamine. A. True B. False

B

What phenotype would be expected in balanced translocation heterozygotes in the absence of position effects? A. Normal, even though they have too much genetic material B. Normal, because they have a normal amount of genetic material C. Abnormal, because they have too much genetic material D. Abnormal, because they lack some genetic material

B

What results would be expected from a plaque assay if the dilution factor of the phage‑infected culture were too low? A. None of these choices B. The entire lawn of bacteria would be lysed. C. The plate would have no plaques. D. The plate would have a few plaques.

B

Which noncoding RNA coats the inactive X-chromosome in regions of heterochromatin? A. HP-1 RNA B. Xist RNA C. tRNA D. 5S rRNA

B

Which of the following arrangements would yield the greatest reduction in gamete viability? A. An inversion heterozygote for a small inversion B. An inversion heterozygote for a large inversion C. An inversion homozygote for a small inversion D.An inversion homozygote for a large inversion

B

Which of the following statements about the T4 lytic life cycle is false? A. The phage takes over the protein synthesis machinery of the bacteria. B. The phage DNA is injected into the host and integrates into the bacterial chromosome. C. The bacterial DNA is degraded. D. The phage produces lysozyme, which ruptures the host cell wall and releases newly formed viral particles.

B

List in order, Lysogenic cycle, Lytic cycle, Both A. - Bacterial chromosome is degraded - Bacterial cell lyses, releasing phage particles - Phage DNA is transcribed and translated to make new phage particles - Phage DNA is packaged into phage heads B. - Phage DNA is integrated into host cell chromosome - Phage DNA is replicated along with the bacterial chromosome during cell division - Bacterial cell survives and divides C. - Phage attaches to host cell - Phage injects its DNA into the host cell - Phage chromosome circulizes

B,A,C

Assume that the genes from the previous example are located along the chromosome in the order X, Y, and Z. What is the probability of recombination between genes X and Z? x = 25% Z = 5% A. 50% B. 5% C. 30% D. 20%

C

If there are two alleles of a gene controlling coat color in a population of mice and the frequency of the dominant allele is 0.3, which of the following must be true? A. There is strong selection against the recessive allele. B. The frequency of homozygous dominant mice in the population is 0.09. C. The frequency of the recessive allele is 0.7. D. There must be a mistake in the calculation because the frequency of the dominant allele cannot be smaller than the frequency of the recessive allele.

C

Light G bands that appear along chromosomes contain ... A. centromeres. B. heterochromatic regions. C. euchromatic regions. D. telomeres.res.

C

Mapping bacterial genes by conjugation is based on which of the following assumptions? A. Bacterial cells are capable of growing in the presence of sodium azide. B. F minus bacterial strains are capable of transferring genes to Hfr strains. C. Genes are transferred from donor to recipient in a linear fashion. D. Conjugation is not disrupted when a bacterial culture is mixed in a blender.

C

Now, suppose that the three tomato genes from Part A did not assort independently, but instead were linked to one another on the same chromosome. Would you expect the phenotypic ratio in the offspring to change? If so, how? A. Lack of independent assortment means that you cannot predict the frequencies of phenotypes in the offspring. B. All eight possible phenotypes would occur in equal numbers in the offspring (1:1:1:1:1:1:1:1). C. All eight possible phenotypes could occur, but a greater proportion of the offspring would have the parental phenotypes. D. Only the parental phenotypes could possibly occur in the offspring.

C

The role of transposase activity in IS element transposition includes _______. A. filling in single-stranded gaps after IS insertion B. regulating expression of the target sequence C. cutting DNA at the target sequence D. truncating other proteins

C

What is a prophage? A. A prophage is a DNA sequence of a phage genome before it packages into particles. B. A prophage is a part of the host cell chromosome adjacent to the inserted bacteriophage genome C. A prophage is a bacteriophage genome that is part of the host cell chromosome. D. A prophage refers to the phage genome sequence before it integrates into the host cell genome.

C

Which of the following is/are true of generalized bacteriophage transduction? A. The bacteriophage chromosome has a region homologous to the bacterial chromosome. B. The bacteriophage must enter the lysogenic cycle C. The bacteriophage packages fragments of bacterial DNA into new phage particles.

C

Which of the following statements about mapping bacterial genes by conjugation is NOT true? A. For any two genes transferred from donor to recipient, all genes residing between them have also been transferred. B. Two genes that are very close together may appear to be transferred at the same time. C. The closer a gene to the Hfr origin, the more likely it will be transferred to the recipient during conjugation. D. It is necessary that all Hfr cells be absent from the population of cells recovered for genotyping.

C

Which of the following statements best describes the relationship between the Hardy-Weinberg principle and the effects of natural selection? A) The Hardy-Weinberg equation assumes that all genotypes occur with equal frequency, but if there is selection against one or more genotypes, equal frequency of all genotypes is not possible. B) If it can be determined that selection favors a particular genotype, the Hardy-Weinberg equation should not be applied. C) If selection can be quantified, relative fitness values can be calculated and used to appropriately modify the Hardy-Weinberg equation. D) Natural selection can influence the genotype frequencies predicted by Hardy-Weinberg, but allele frequencies are not affected.

C

Which of the following statements regarding familial Down syndrome is false? A. Heterozygous carriers of the Robertsonian translocation that causes familial Down syndrome can have children who are phenotypically normal and are not carriers of the translocation. B. Heterozygous carriers of the Robertsonian translocation that cause familial Down syndrome can have children who are also carriers of the translocation. C. If one parent is a translocation heterozygote for chromosomes 14/21, a child born to this parent is as likely to have Down syndrome as he is to be normal. D. It accounts for approximately 5% of all Down syndrome cases.

C

Which of the following syndromes is not paired with its causative chromosomal aberration? A. Huntington disease - duplication B. Down syndrome - Robertsonian translocation C. Fragile X syndrome - deletion D. Cri du chat syndrome - deletion

C

Which of the following transposition events is most likely to result in a loss of function mutation? A. Insertion near the promoter region of a gene B. Transposition of an IS element that contains a stop codon within the inverted repeat sequence C. Insertion of an IS element within the coding region of a gene

C

All of the following are characteristics of insertion sequences elements except _______. A. there can be more than one copy of an IS element in a bacterial genome B. they encode protein C. they are flanked by inverted repeats D. a copy of the insertion sequence becomes integrated at a new location

D

All of the following events occur during normal meiosis except _______ A. homologous chromosomes separate from one another during meiosis I B. one diploid cell produces four haploid cell C. sister chromatids separate from one another during meiosis II D. two haploid gametes fuse to form a diploid cell

D

Assume that the DNA associated with a nucleosome core particle plus the DNA in the linker adds up to 200 bp. Approximately how many base pairs are found in the linker region? A. ~11 B. ~34 C. ~200 D. ~54 E. ~146

D

For linked genes A, B, and C, the map distance A-B is 5 map units and the map distance B-C is 25 map units. If there are 10 double crossover events out of 1000 offspring, what is the interference? A. 0.8 B. 0.01 C. 0.0125 D. 0.2

D

Histone acetyltransferases (HATs) are capable of remodeling chromatin by adding acetyl groups to various lysine residues in histones that comprise the nucleosome. Following this modification, the lysine residue no longer has a positive charge. Which statement is true? A. Histones in general have a net positive charge that allow them to bind to DNA. Acetylation of histones, decreases their positive charge and strengthens the histone-DNA interaction. B. Histones in general have a net negative charge that allow them to bind to DNA. Acetylation of histones, decreases their positive charge and strengthens the histone-DNA interaction C. Histones in general have a net negative charge that allow them to bind to DNA. Acetylation of histones, decreases their positive charge and weakens the histone-DNA interaction. D. Histones in general have a net positive charge that allow them to bind to DNA. Acetylation of histones, decreases their positive charge and weakens the histone-DNA interaction.

D

How is a merozygote formed? A. The F factor is inserted into the chromosome of an F− cell, causing it to become an Hfr strain. B. The F factor is inserted into the chromosome of an F+ cell, causing it to revert to F−. C. The F factor is excised from the chromosome of an Hfr strain, causing it to revert to F−. D. The F factor and several adjacent genes are excised from the chromosome of an F+ cell and transferred to an F− strain.

D

How is a prophage formed? A. It is formed by random integration of a bacteriophage chromosome into the host cell chromosome. B. It is formed by circularization of phage DNA injected into the host cell. C. It is formed by replication of a bacteriophage chromosome into the host cell chromosome. D. It is formed by integration of a bacteriophage chromosome into the host cell chromosome by site-specific recombination.

D

In a three‑point mapping experiment for the genes y‑w‑ec, the following percentages of events are observed: NCO events: 65%; SCO events between y and w: 15%; SCO events between y and ec: 17%; DCO events: 3% What is the map distance between y and ec? A. 17 map units B. 15 map units C. 18 map units D. 20 map units

D

Which of the following statements about conjugation is true? A. Only competent cells can undergo conjugation. B. One strand of DNA from an F+ cell integrates into the chromosome of an F- cell, and the other strand is degraded. C. The F factor is an element that is found in the chromosome of an F+ cell. D. DNA is transferred from an F+ cell to an F− cell.

D

Which of the following statements about gamete formation during meiosis is false? A. Parental gametes contain the same combinations of linked genes as found in the parent cell. B. Complete linkage results in the formation of only parental gametes. C. Recombinant gametes contain combinations of alleles not found in the parent cell. D. Parental gametes can be formed only if there is no crossing over during meiosis.

D

Which of the following statements best describes the relationship between fitness and selection coefficient (s)? A) Fitness is a qualitative measure whereas selection is a quantitative measure. B) The lower the fitness value associated with a given genotype, the weaker the selection against that genotype. C) The higher the fitness value associated with a given genotype, the stronger the selection against that genotype. D) The stronger the selection against a given genotype, the lower the fitness associated with that genotype.

D

With respect to the chromosomes involved in the translocation, 14 and 21, what is the total number of different gametes possible for a heterozygous carrier parent to produce? A. 4 B. 2 C. 3 D. 6

D

Which of the following statements about allopolyploid individuals is true? A. They can be formed when two sperm simultaneously fertilize an ovum within the same species. B. They are generated from exposure to colchicine. C. They result from a mating between individuals of the same species. D. They may be sterile and unable to produce offspring.

D.

Antibiotic-resistant bacteria are becoming an increasing problem. Some bacteria that were once killed by common antibiotics have acquired the ability to survive in the presence of those antibiotics. How can bacteria acquire antibiotic resistance? A. Bacteria can pick up an antibiotic-resistance gene from the environment through transformation. B. Bacteria can acquire random mutations that allow them to grow in the presence of antibiotics. C. Bacteria can gain an antibiotic-resistance gene by conjugating with another species of bacteria. D. Bacteria can acquire antibiotic-resistance genes by becoming infected with a virus that contains an antibiotic-resistance gene. E. All of the above

E