Chromosome Rearrangements Verified Test Bank Chapter 13 6e

Genetics, 6e (Hartwell)

Chapter 13 Chromosomal Rearrangements and Changes in Chromosome Number

1) What are the four major classes of chromosomal rearrangements?

A) inversions, duplications, translocations, deletions

B) duplications,  reciprocal translocations, nonreciprocal translocations, inversions

C) deletions, inversions, duplications, point mutations

D) translocations, pericentric inversions, paracentric inversions, deletions

2) The type of mutation that results in a loss of material from the genome is called what?

A) inversion

B) duplication

C) deletion

D) translocation

3) What type of mutation adds material to the genome?

A) inversion

B) duplication

C) deletion

D) translocation

4) Which type of mutation is most likely to result in lethality?

A) inversion

B) duplication

C) deletion

D) translocation

5) What is the movement of part of one chromosome to another chromosome called?

A) inversion

B) duplication

C) deletion

D) translocation

6) What is a segment of DNA that can use transposase to move from one place in the genome to another called?

A) regulatory region

B) duplication

C) translocation

D) DNA transposon

E) retrotranposon

7) An acentric fragment is one result of crossing-over between a normal chromosome and a chromosome that has undergone what kind of mutation?

A) paracentric inversion

B) duplication

C) reciprocal translocation

D) pericentric inversion

8) Karyotypes generally remain constant within a species because

A) rearrangements occur frequently.

B) changes in chromosome number occur infrequently.

C) genetic instabilities produced by genomic changes are usually at a selective disadvantage.

D) genetic imbalances are often at a selective advantage.

9) Despite selection against chromosomal variations,

A) related species almost always have the same karyotype.

B) related species almost always have different karyotypes.

C) closely related species diverge by many chromosomal rearrangements.

D) distantly related species diverge by only a few chromosomal rearrangements.

10) FISH analysis is likely to detect which type of change in DNA? (Select all that apply.)

A) translocations

B) duplications

C) deletions

D) silent point mutations

E) frameshift point mutations

11) An individual with one normal homolog and one homolog with a deletion is called what?

A) a deletion heterozygote

B) a deletion homozygote

C) dosage compensation

D) haploinsufficient

12) In a deletion heterozygote, the normal chromosome will form what structure during prophase of meiosis I?

A) inversion loop

B) cruciform

C) slipped mispairing

D) deletion loop

13) Which process can cause duplications? (Select all that apply.)

A) repair of one double-strand break by homologous recombination

B) repair of two double-strand breaks that occur in different places on different sister chromatids

C) repair of two double-strand breaks that occur in the same chromatid by nonhomologous end-joining

D) misalignment of homologous chromosomes at repetitive sequences followed by crossing-over

E) a mutagen that introduces point mutations

14) Which event could result in an inversion?

A) A 360° rotation of a chromosomal region following two double-strand breaks in a chromosome's DNA.

B) A crossover between two DNA sequences in different places on the same chromosome and that are inverted repeats of each other.

C) A crossover between two repeated DNA sequences that are in different places on the same chromosome and are oriented in the same direction.

D) A crossover between two repetitive sequences on different chromosomes.

15) Inversions may be difficult to detect because they

A) never visibly change chromosome banding patterns.

B) increase recombination in heterozygotes.

C) do not always cause an abnormal phenotype.

D) normally are removed immediately in natural populations.

16) Which are possible results of an intragenic inversion (an inversion contained within a gene)? (Select all that apply.)

A) A normal protein may be produced.

B) Some of the gene's DNA sequences will be adjacent to DNA sequences to which they are not normally adjacent.

C) All of the gene's A, C, G, and T bases remain in the same order as normal.

D) The order of genes along the chromosome may be different than normal.

17) When a crossover occurs within the inversion loop of a pericentric inversion, each recombinant chromatid will have

(Select all that apply.)

A) a dicentric bridge.

B) a duplication of some genes in the inverted region.

C) a deletion of some genes in the inverted region.

D) one copy of each gene, with some genes in a different order than normal.

E) one copy of each gene in the normal order.

18) Which gamete genotypes are expected to contribute to viable offspring when an individual is heterozygous for a paracentric inversion and crossing-over occurs as shown in the diagram? (The ● symbol represents a centromere.)

(Select all that apply.)

A) ● A B C D E

B) ● a d c b e

C) e b c D E

D) ● A B C d e

E) A B C ● d a

F) e b c ● D E

G) A B C ● D E

H) a d ● c b e

J) ● A B C d a ●

19) Which gamete genotypes are expected to contribute to viable offspring when an individual is heterozygous for a pericentric inversion and crossing-over occurs as shown in the diagram? (The ● symbol represents a centromere.)

(Select all that apply.)

A) ● A B C D E

B) ● A B C d a ●

C) ● a d c b e

D) e b c D E

E) ● A B C d e

F) A B C ● d a

G) e b c ● D E

H) A B C ● D E

J) a d ● c b e

20) In plants, genes E, F, and G are on one chromosome arm. Alternate dominant and recessive alleles of all three genes determine visible traits: E = normal leaf number, e = extra leaves, F = normal stems, f = furry stems, G = normal flower size, g = gigantic flowers. A plant that is heterozygous for an inversion involving all three genes is crossed to a plant with extra leaves, furry stems, and gigantic flowers. The arrangement of alleles is shown in the diagram. If you look at thousands of offspring of this cross, what phenotypes do you expect to see?

(Select all that apply.)

A) Most, but not all, offspring will be normal for all three traits or have extra leaves, furry stems, and gigantic flowers.

B) Due to double crossovers between E and F and F and G, a very small number of offspring will have only furry stems, or only extra leaves and gigantic flowers.

C) Half of the offspring will be normal for all three traits and half will have extra leaves, furry stems, and gigantic flowers.

D) Due to crossovers between E and F in parent 1, a small number of offspring will have only extra leaves, or only furry stems and gigantic flower size.

E) Due to crossovers between F and G, a small number of offspring will have only extra leaves and furry stems, or only gigantic flower size.

21) Robertsonian translocations result from which of the following?

A) Breaks occur at or near the centromeres of two acrocentric chromosomes followed by the reciprocal exchange of broken parts.

B) Two homologous chromosomes break and exchange parts.

C) Unequal crossing-over occurs during meiosis.

D) Two small chromosomes fuse end-to-end resulting in one chromosome with two centromeres.

22) Which of the following chromosomal rearrangements usually results in normal meiosis?

A) translocation heterozygote

B) translocation homozygote

C) paracentric inversion heterozygote

D) pericentric inversion heterozygote

23) Which segregation pattern in a translocation heterozygote is likely to result in a normal zygote after fertilization?

A) alternate

B) adjacent-1

C) adjacent-2

D) nondisjunction

24) An individual with which type of chromosomal rearrangement is expected to have the lowest fertility?

A) chromosomal duplication

B) pericentric inversion

C) translocation heterozygote

D) translocation homozygote

E) paracentric inversion

25) What is true in translocation heterozygotes?

A) At the borders of translocations, genes that are normally located on different homologs appear to be linked.

B) Fertility is reduced because only alternate segregation results in balanced gametes.

C) The translocation chromosome is used as a balancer because it cannot cross over with a normal chromosome.

D) Crossing over between normal and translocation chromosomes results in an inversion.

26) Which can result in Down syndrome? (Select all that apply.)

A) nondisjunction resulting in an extra chromosome 21

B) a reciprocal translocation between acrocentric chromosomes 14 and 21

C) deletions of a segment of chromosome 21

D) having the triploid number of chromosomes

27) What is true about reciprocal translocation heterozygotes and inversions? (Select all that apply.)

A) The amount of DNA in the genome remains the same.

B) The genes at the boundaries may be disrupted, while those in the middle are most likely unaffected.

C) Up to 50% of gametes may be unbalanced, resulting in semisterility.

D) They are both used to make Balancer chromosomes.

28) Which is a characteristic of retrotransposons, but not of DNA transposons?

A) include a gene that encodes reverse transcriptase

B) may be present in a genome from one to millions of times

C) found only in humans

D) may not have a function in their host

E) have short DNA sequences that are inverted repeats of each other on the ends

29) One similarity between DNA transposons and retrotransposons is that

A) during transposition, both go through an RNA form that is copied back into DNA.

B) both can encode an enzyme required for mobilization.

C) transposition results in movement of the original transposon to a different place in the genome.

D) they both have poly-A segments at one end.

30) Which is a mechanism by which transposable element mobilization may be controlled by the cell? (Select all that apply.)

A) blocking transcription of transposable element genes

B) blocking translation of transposable element transcripts

C) alternative splicing of transposable element transcripts

D) synthesizing an enzyme that removes transposable elements from the genome

E) increasing the mutation rate of transposable element DNA sequences

31) What might be the outcome of repeated duplications of one or a few genes in a species' genome?

A) tetraploidy

B) semisterility

C) the presence of gene families

D) repetitive DNA that is of no use to the cell

E) fusion of segments of two chromosomes into one

32) On the island of Madeira, two populations of house mice have accumulated different Robertsonian translocations. Which are true about these two populations of mice? (Select all that apply.)

A) They have fewer chromosomes than mice in other areas of the world.

B) They are isolated from each other geographically.

C) If mice from different populations mate, their offspring are sterile.

D) Mice from different populations are unable to mate with each other.

E) They are becoming extinct because of semisterility.

33) What might result from movement of transposable elements in a species' genome? (Select all that apply.)

A) The level of expression of one or more genes could be changed.

B) A gene could be moved from one chromosome to another.

C) A segment of DNA could be duplicated or deleted.

D) The rate of point mutation could increase.

34) In what way can defective transposable elements alter genomes even if they cannot mobilize? (Select all that apply.)

A) Crossing-over between transposable elements on the same chromosome can result in a deletion or an inversion.

B) Crossing-over between transposable elements on nonhomologous chromosomes can result in a reciprocal translocation.

C) Genes located between two transposable elements could be moved to a nonhomologous chromosome.

D) Proteins produced by the defective transposable elements introduce point mutations in other areas of the genome.

35) Which is not an example of aneuploidy?

A) monosomy

B) tetraploidy

C) trisomy

D) nullisomy

36) What is a reason that aneuploidy in sex chromosomes is generally better tolerated than aneuploidy in autosomal chromosomes in humans?

A) In somatic cells, most of the genes on only one X chromosome are transcriptionally active.

B) Autosomal aneuploidy leads to heart defects and death in utero.

C) Y chromosome duplication results in only minor changes in testosterone levels.

D) Sex chromosome aneuploids may occur as the result of fertilization, but extra sex chromosomes are removed from the developing embryo during subsequent mitosis.

E) Any change in autosome number results in increased susceptibility to infection.

37) Which sex chromosome aneuploidy is not usually seen in live births?

A) XO

B) XXY

C) YO

D) XXX

38) Turner syndrome (XO) is a sex chromosome aneuploidy. Of the effects listed below, which one is not usually seen in this syndrome?

A) unusually short stature

B) infertility

C) skeletal abnormalities

D) unusually long limbs

39) In Drosophila, a gynandromorph, which is composed of equal parts of male and female tissue, results from

A) an XX female losing one X chromosome during the first mitotic division after fertilization.

B) an egg carrying an X chromosome fertilized by a Y-carrying sperm.

C) a normal egg fertilized by both an X-carrying sperm and a Y-carrying sperm.

D) the fusion of a female embryo with a male embryo.

40) Which is not an example of euploidy?

A) Seedless watermelons have three copies of each chromosome.

B) A normal human has two copies of each chromosome.

C) A human with Down syndrome has three copies of chromosome 21.

D) Commercially grown strawberry plants have eight copies of each chromosome.

41) Triploid organisms usually result from

A) the union of monoploid and diploid gametes.

B) nondisjunction during mitosis.

C) propagation of fused cell lines.

D) a fertilization event that involves three monoploid gametes.

E) normal fertilization of gametes produced by triploid parents.

42) During mitosis, if all of the chromosomes in a diploid cell fail to separate and instead segregate into one daughter cell, the result will be what?

A) one monoploid daughter cell and one triploid daughter cell

B) one 2x-1 daughter cell and one 2x+1 daughter cell

C) two 2x daughter cells

D) only one tetraploid daughter cell

43) Hybrids in which the chromosome sets come from two distinct, though related, species are known as

A) autopolyploids.

B) allopolyploids.

C) aneuploids.

D) bivalents.

44) Triticale is an allopolyploid hybrid between wheat and rye. Some strains of Triticale show agricultural promise because

(Select all that apply.)

A) they combine the high yields of wheat with the ability adapt to unfavorable environments like rye.

B) the grain is high in protein, especially the amino acid lysine.

C) they combine desirable traits from wheat and rye in one crop plant.

D) they are sterile because the wheat and rye chromosomes cannot pair during meiosis.

45) Why are organisms with an odd number of chromosome sets usually sterile?

A) Almost all gametes will have an unbalanced set of chromosomes.

B) Chromosomes will fail to segregate independently during meiosis I.

C) Chromosomes will fail to segregate independently during meiosis II.

D) Because an odd number of chromosomal sets is present, meiosis will not occur at all.

46) Which is a mechanism by which chromosomal rearrangements produce proteins with altered amino acid sequence?

A) Chromosome sets from two different species are combined in one individual.

B) Translocations may fuse two different open reading frames.

C) Deletions may remove regulatory regions of genes.

D) Inversions may move a gene from euchromatin to heterochromatin.

Match the description with the appropriate term.

47) A segment of DNA that moves from place to place in the genome

48) Addition of one or more copies of a segment of DNA to the genome

49) A change in the orientation of a DNA sequence

50) Loss of a segment of DNA from the genome

51) Fusion of a segment of a chromosome with part of a nonhomologous chromosome

Match the description with the appropriate term.

52) Broad term for any DNA segment that moves about in the genome

53) Moves in the genome through an RNA intermediate

54) DNA is removed from the genome and moved to a new position.

55) An enzyme that catalyzes the movement of DNA transposons

56) Deletions are most useful for gene mapping

A) when you have a mutant allele of a gene that is recessive to normal alleles and amorphic.

B) when you have a mutant allele of a gene that is dominant to wild-type alleles.

C) if you have a mutant allele of a gene that results in no detectable mutant phenotype when homozygous.

D) if you have a gain-of-function mutant allele of a gene.

57) Inversions are most likely to affect an organism's phenotype

A) if one or both of the inversion's breakpoints lies within the transcribed region of a gene.

B) if the inversion's breakpoints are on either side of a gene and its regulatory regions and the entire gene is reversed in the genome.

C) if the inversion is pericentric.

D) if the inversion is paracentric.

E) if the inversion is small.

58) What mechanism used for mobilization of transposable elements can lead to deletions in genomes?

A) Transposase sometimes deletes genomic DNA while removing DNA transposons from the genome.

B) Alignment of two transposable elements is required for mobilization and misalignment can result in deletions.

C) RNA polymerase transcribes transposable elements; when it makes mistakes, DNA nucleotides are sometimes deleted.

D) Piwi RNAs inhibit movement of transposons by deleting DNA that includes and surrounds the inverted repeats.

59) Monoploids are useful in plant breeding because

A) they can be used to select for plants with desirable recessive traits.

B) they will not express any undesirable recessive traits.

C) they are one step in the path to creating desirable polyploid plants.

D) they are typically resistant to commercial herbicides.

Wild oysters are diploid and have 20 chromosomes in somatic cells. Scientists have generated tetraploid oysters using colchicine to prevent separation of sister chromatids. Crossing a diploid oyster with a tetraploid oyster resulted in triploid oysters that are commercially advantageous because they are larger and do not have a reproductive phase that usually interrupts the harvesting season.

60) What is x in wild oysters?

A) 5

B) 10

C) 20

D) 40

61) What is n in wild oysters?

A) 5

B) 10

C) 20

D) 40

62) What is x in tetraploid oysters?

A) 5

B) 10

C) 20

D) 40

63) What is n in tetraploid oysters?

A) 5

B) 10

C) 20

D) 40

64) What is the probability that a gamete produced by a triploid oyster will be balanced?

A) 1/1024

B) 1/512

C) 1/20

D) very close to 1