Deck 16: Variations in Chromosome Structure and Number

Question 1

Nondisjunction of chromosomes may result in

A)the loss of one homologous chromosome pair.
B)the addition of one homologous chromosome pair.
C)the addition of a single chromosome.
D)the loss of a single chromosome.
E)All of these

Answer 1

E

Question 2

Which of the following types of analysis allows scientists to visualize an individual's chromosomal makeup?

A)Karyotype analysis
B)Pedigree analysis
C)Genetic crosses
D)Inheritance analysis
E)Deletion mapping

Answer 2

A

Question 3

Which of the following types of chromosomal mutation cannot revert to the wild-type state?

A)Duplication
B)Deletion
C)Translocation
D)Inversion
E)Any of these may revert to wild-type

Answer 3

B

Question 4

An X-linked homozygous color-blind woman gives birth to a son who is not color blind.He could have normal vision because he

A)has Down syndrome.
B)has Klinefelter syndrome.
C)has Turner syndrome.
D)is XYY.
E)has triploidy.

Question 5

What is the genetic consequence of a homozygous translocation?

A)Inviable gamete formation (semisterility)
B)Gene duplications and deletions
C)Formation of abnormal chromatids following crossing-over
D)Abnormal pairing during meiosis
E)An alteration in the linkage relationships of genes

Question 6

The chemical colchicine prevents the formation of microtubules.It is commonly used in certain experimental procedures to cause changes in cellular chromosomes.Which of the following changes is it likely to be used to create?

A)Induction of mutant polyploid individuals
B)Induction of mutant aneuploid individuals
C)Prevention of nondisjunction in cell cultures
D)Induction of chromosomal deletions in experimental cell lines
E)Induction of chromosomal duplications in experimental cell lines

Question 7

Many scientists believe that the evolution of multigene families,such as the genes for hemoglobin,is a result of which type of genetic rearrangement?

A)Duplication
B)Deletion
C)Inversion
D)Reciprocal translocation
E)Nonreciprocal translocation

Question 8

If a small region of a chromosome containing a non-essential gene is completely deleted,and an organism has two identical chromosomes with this deletion,then the organism

A)has no alleles of that gene.
B)is dead.
C)has more heterochromatin.
D)has recessive alleles of those genes.
E)will exhibit pseudodominance.

Question 9

In familial Down syndrome resulting from Robertsonian translocation,

A)the affected individual has three copies of the complete chromosome 21.
B)the affected individual is missing a copy of chromosome 21.
C)the affected individual has three copies of the long arm of chromosome 21,one of which is attached to part of chromosome 14.
D)the affected individual has two copies of the long arm of chromosome 21,one of which is attached to part of chromosome 14.
E)the affected individual has three copies of the long arm of chromosome 14,one of which is attached to chromosome 21.

Question 10

Which of the following is not used to help identify individual chromosomes in a karyotype?

A)Centromere position
B)Point mutations
C)Chromosome size
D)Banding pattern on staining
E)Heterochromatin regions

Question 11

A(n)________ inversion includes the centromere.

A)concentric
B)pericentric
C)paracentric
D)epicentric
E)chromocentric

Question 12

Seedless bananas are produced from

A)sterile tetraploid allopolyploid plants.
B)sterile triploid autopolyploid plants.
C)monoploid plants grown from unfertilized seeds.
D)fertile diploid plants that are unfertilized.
E)Both C and D

Question 13

Most monoploid individuals do not survive because

A)they do not have the appropriate gene dosages.
B)their cells cannot divide properly.
C)recessive lethal mutations cannot be masked by dominant alleles.
D)they have missing genes.
E)they have only one sex chromosome.

Question 14

Which of the following traits is determined by programmed transposition?

A)Pattern baldness in humans
B)Mating types in yeast
C)Eye color in Drosophila
D)All of these
E)None of these

Question 15

In Drosophila melanogaster,polytene chromosomes are produced when

A)a chromosome breaks and rejoins with another section of the same chromosome.
B)a cell divides several times before the chromosomes are duplicated.
C)chromosomes are duplicated repeatedly without a corresponding nuclear division.
D)a segment of a chromosome is duplicated during an unequal crossing-over event.
E)characteristic banding patterns form on the chromosomes.

Question 16

A dicentric chromosome has two

A)arms.
B)centromeres.
C)telomeres.
D)mutations.
E)centrosomes.

Question 17

A human cell containing two sets of 23 chromosomes is

A)aneuploid.
B)polyploid.
C)euploid.
D)haploid.
E)None of these

Question 18

A monosomic cell would produce gametes with how many chromosomes?

A)N
B)N and N-1
C)N-1
D)N+1
E)N and N+1

Question 19

How does a Philadelphia chromosome occur,and what condition does it cause?

Question 20

A tetraploid cell contains four chromosomes.

Question 21

How is hybrid sterility overcome in allopolyploid plants?

Question 22

Approximately 15% of all human conceptions contain at least one chromosomal mutation.

Question 23

What are all the possible gametic genotypes produced by a trisomic individual that is genotype A/A^+/B for the trisomic chromosome?

Question 24

In some fruit flies,an inversion involving the white-eyed locus (w)moves the w⁺gene from one end of the X chromosome to a location nearer to the centromere.Flies with a w⁺ or w⁺/w genotype are normally expected to have red eyes.However,in flies with the inversion,the eyes are mottled red and white.Explain why.

Question 25

No known living humans have one whole chromosome of a homologous pair of autosomes deleted from the genome.

Question 26

How can the banding patterns on Drosophila polytene chromosomes be used to aid deletion mapping of genes on the chromosomes?

Question 27

What are the gametic consequences of a lack of cytokinesis following the first or second meiotic division?

Question 28

A woman with normal vision,whose father has sex-linked color blindness,marries a man with normal vision.They have a son who has Klinefelter syndrome and is color blind.Describe precisely what kind of event could caused have his Klinefelter syndrome.

Question 29

Cultivated wheat is descended from three distinct species,each with a diploid set of 14 chromosomes.Thus,it is

A)an allotriploid with 21 chromosomes.
B)an allotriploid with 42 chromosomes.
C)an allohexaploid with 84 chromosomes.
D)an allohexaploid with 42 chromosomes.
E)an autotetraploid with 28 chromosomes.

Question 30

Down syndrome (trisomy-21)is the only human autosomal trisomy in which the individuals may survive to adulthood.

Question 31

Why do polyploid individuals with an even number of chromosome sets have a higher likelihood of fertility than those with an odd number of chromosome sets?

Question 32

The causes of chromosomal deletion may include radiation,viral infection,chemical exposure,or transposable elements.

Question 33

The diagram below shows a region near the center of a long arm of a chromosome.Assume that in the diagram below,every vertical hatch mark is 1 map unit from the next vertical hatch mark.The dashed double line represents an inversion.If you crossed this heterozygous individual with a normal homozygous recessive individual,and produced 1000 live offspring,how many would you expect to be Aa dd?

Question 34

During meiosis in a reciprocal translocation heterozygote,what are the three ways that chromosomes may segregate at anaphase I,and what are the consequences for the resulting gametes?

Question 35

In humans,many types of cancers are associated with chromosomal mutations.

Question 36

Both changes in chromosome number and chromosome structure are believed to have resulted in novel genomes,leading to new species.

Question 37

Inversion loops form to allow homologous chromosomes containing homozygous inversions to pair properly during meiosis.

Question 38

For eukaryotic organisms,polyploidy is always a lethal condition.

Question 39

A paracentric inversion heterozygote contains a normal chromosome with the long-arm gene order GENE and an inverted chromosome with the long-arm gene order GNEE.They form an inversion loop to pair during prophase I of meiosis.If a single crossover occurs between the G and the E segments of the loop,what will be the gene orders in the resulting recombinant dicentric chromosome and acentric fragment? Assume crossing over occurs at the four-strand stage involving two nonsister chromatids.

Question 40

During meiosis,what are the gametic consequences of a paracentric inversion with a single crossover event,compared to a pericentric inversion with a single crossover?