Deck 6: Chromosome Variation

Question 1

Which type of chromosome has the centromere at or very near the end?

A)Acrocentric
B)Metacentric
C)Paracentric
D)Submetacentric
E)Telocentric

Answer 1

E

Question 2

Which of the following is a form of aneuploidy in which two members of the same homologous pair are absent?

A)Nullisomy
B)Monosomy
C)Disomy
D)Trisomy
E)Tetrasomy

Answer 2

A

Question 3

Which type of chromosome mutation results in a chromosome segment that is turned 180 degrees?

A)Deletion
B)Duplication
C)Inversion
D)Translocation
E)Transversion

Answer 3

C

Question 4

How is colchicine useful for studying chromosomal mutations?

A)Colchicine inhibits microtubule polymerization, which stalls cells in metaphase with condensed chromosomes that can be observed with a microscope.
B)Colchicine induces chromosome condensation during interphase, which allows the visualization of interphase chromosomes.
C)Colchicine causes chromosomal breakage, leading to inversions and translocations that can be observed with a microscope.
D)Colchicine aids in the formation of microtubules during mitosis, which promotes anaphase and completion of the cell cycle.
E)Colchicine is an inhibitor of oxidative phosphorylation.Reduced mitochondrial function slows down mitosis and increases the number of metaphase cells.

Question 5

Which type of chromosome mutation increases the amount of genetic material?

A)Deletion
B)Duplication
C)Inversion
D)Translocation
E)Transversion

Question 6

Which type of chromosome mutation decreases the amount of genetic material?

A)Deletion
B)Duplication
C)Inversion
D)Translocation
E)Transversion

Question 7

Which of the following chromosome mutations would NOT cause loops to form during chromosome pairing in prophase I of meiosis?

A)Chromosome deletion
B)Tandem duplication
C)Paracentric inversion
D)Pericentric inversion
E)Reciprocal translocation

Question 8

Which form of aneuploidy describes an organism that is missing a single chromosome?

A)Nullisomy
B)Monosomy
C)Disomy
D)Trisomy
E)Tetrasomy

Question 9

Which type of chromosome has a centromere displaced toward one end, creating a long arm and a short arm?

A)Acrocentric
B)Metacentric
C)Paracentric
D)Submetacentric
E)Telocentric

Question 10

Which type of chromosome mutation INCREASES the amount of genetic material for all chromosomes?

A)Translocation
B)Aneuploidy
C)Polyploidy
D)Inversion
E)Transversion

Question 11

_____ can cause genes to move from one linkage group to another.

A)Inversions
B)Deletions
C)Polyploidy
D)Translocations
E)Unequal crossing over

Question 12

Approximately _____ of the gametes produced by an individual heterozygous for a translocation will be nonviable.

A)all
B)half
C)none
D)one-quarter
E)one-eighth

Question 13

Chimpanzees, gorillas, and orangutans all have 48 chromosomes, whereas humans have 46 chromosomes.Human chromosome 2 is a large, metacentric chromosome with G-banding patterns that closely match those found on two different acrocentric chromosomes of the apes.What would BEST explain these findings?

A)A translocation took place in a human ancestor, creating a large metacentric chromosome from the two long arms of the ancestral acrocentric chromosomes.The other small chromosome produced by this translocation was lost.
B)Meiotic nondisjunction gave rise to a nullisomic gamete.The fusion of two nullisomic gametes produced the ancestor of the human species with 46 chromosomes instead of 48 chromosomes.
C)A nonreciprocal translocation and subsequent fusion of the chromosomal fragments created a genome of 46 chromosomes without the loss of any genetic information.
D)Infection by a primate virus created a new chromosome when the viral DNA became a permanent part of the genome.Humans were not affected by this virus, so they did not acquire the extra chromosome.
E)Humans have the correct number of chromosomes.The extra chromosome pair in the other apes is a classic case of tetrasomy as a result of meiotic nondisjunction in the primate ancestor.

Question 14

Which type of chromosome mutation can DECREASE the amount of genetic material for one entire chromosome?

A)Translocation
B)Aneuploidy
C)Polyploidy
D)Inversion
E)Transversion

Question 15

Which type of chromosome has the centromere near one end, producing a long arm and a knob?

A)Acrocentric
B)Metacentric
C)Paracentric
D)Submetacentric
E)Telocentric

Question 16

A constriction or gap at particular locations on a chromosome that is prone to breakage under certain conditions is called:

A)chromosome inversion.
B)fragile site.
C)copy-number variation.
D)nondisjunction.
E)aneuploidy.

Question 17

The complete set of chromosomes possessed by an organism is called a:

A)polyploid.
B)chromatin complement.
C)karyotype.
D)phenotype.
E)diploid.

Question 18

Which of the following concepts is NOT associated with differences in the number of copies of particular DNA sequences?

A)Chromosome deletions
B)Chromosome duplications
C)Chromosome inversion
D)Red-green color blindness in humans
E)Bar phenotype in Drosophila

Question 19

Which of the following is NOT a rearrangement that causes chromosomal mutations?

A)Deletion
B)Duplication
C)Inversion
D)Translocation
E)Transversion

Question 20

Which type of chromosome has the centromere located approximately in the middle?

A)Acrocentric
B)Metacentric
C)Paracentric
D)Submetacentric
E)Telocentric

Question 21

A woman has a condition where all of her gametes undergo nondisjunction of chromosome 21 in meiosis I, but meiosis II proceeds normally.She mates with a man who produces all normal gametes.What is the probability that the fertilized egg will develop into a child with Down syndrome? Assume that all gametes and zygotes are viable.

A)1/8
B)1/4
C)1/3
D)1/2
E)0

Question 22

A plant species has 2n = 18 chromosomes.How many chromosomes would you expect to find in a tetrasomic individual of this species?

A)17
B)19
C)20
D)22
E)36

Question 23

A man has a condition where all of his gametes undergo nondisjunction of the sex chromosomes in meiosis I, but meiosis II proceeds normally.He mates with a woman who produces all normal gametes.What is the probability that the fertilized egg will develop into a child with Klinefelter syndrome (XXY)? Assume that all gametes and zygotes are viable.

A)1/8
B)1/4
C)1/3
D)1/2
E)0

Question 24

Wild-type Arabidopsis has five chromosomes (2n = 10).Trisomic plants are designated as Tr followed by the trisomic chromosome number-that is, Tr1 is trisomic for chromosome 1.Assuming that trisomy is fully viable and that all possible pairing configurations (including nonpairing)are possible at meiosis, what proportion of the progeny from the cross Tr1 × Tr1 will have a wild-type chromosomal complement?

A)1/2
B)1/3
C)1/4
D)1/9
E)1/81

Question 25

What would be the consequence of a diploid gamete (resulting from meiotic nondisjunction)being fertilized by a haploid gamete from the same species?

A)Allodiploid
B)Allotriploid
C)Autotriploid
D)Allotetraploid
E)Autotetraploid

Question 26

A man has a condition where all of his gametes undergo meiosis I normally, but there is nondisjunction of the sex chromosomes in every meiosis II.He mates with a woman who produces all normal gametes.What is the probability that the fertilized egg will develop into a child with Klinefelter syndrome (XXY)? Assume that all gametes and zygotes are viable.

A)1/8
B)1/4
C)1/3
D)1/2
E)0

Question 27

Which form of aneuploidy causes primary Down syndrome?

A)Nullisomy
B)Monosomy
C)Disomy
D)Trisomy
E)Tetrasomy

Question 28

Which of the following is a form of aneuploidy in which four members of the same homologous pair are present?

A)Nullisomy
B)Monosomy
C)Disomy
D)Trisomy
E)Tetrasomy

Question 29

Which type of polyploidy is synonymous with amphidiploid?

A)Allodiploid
B)Allotriploid
C)Autotriploid
D)Allotetraploid
E)Autotetraploid

Question 30

Which of the following is NOT a form of aneuploidy in diploid organisms?

A)Nullisomy
B)Monosomy
C)Disomy
D)Trisomy
E)Tetrasomy

Question 31

Wild-type Arabidopsis has five chromosomes (2n = 10).Trisomic plants are designated as Tr followed by the trisomic chromosome number-that is, Tr1 is trisomic for chromosome 1.Assuming that trisomy is fully viable and that all possible pairing configurations (including nonpairing)are possible at meiosis, what proportion of the progeny from the cross Tr1;Tr2 × Tr1;Tr2 will have a wild-type chromosomal complement?

A)1/2
B)1/3
C)1/4
D)1/9
E)1/81

Question 32

Wild-type Arabidopsis has five chromosomes (2n = 10).Trisomic plants are designated as Tr followed by the trisomic chromosome number-that is, Tr1 is trisomic for chromosome 1.Assuming that trisomy is fully viable and that all possible pairing configurations (including nonpairing)are possible at meiosis, what proportion of the progeny from the cross wt × Tr1;Tr2 will have a wild-type chromosomal complement?

A)1/2
B)1/3
C)1/4
D)1/9
E)1/81

Question 33

What is responsible for primary Down syndrome?

A)Disomy
B)Inversion
C)Nondisjunction
D)Polyploidy
E)Translocation

Question 34

Which type of chromosome mutation is responsible for familial Down syndrome?

A)Disomy
B)Inversion
C)Nondisjunction
D)Polyploidy
E)Translocation

Question 35

Wild-type Arabidopsis has five chromosomes (2n = 10).Trisomic plants are designated as Tr followed by the trisomic chromosome number-that is, Tr1 is trisomic for chromosome 1.Assuming that trisomy is fully viable and that all possible pairing configurations (including nonpairing)are possible at meiosis, what proportion of the progeny from the cross wt × Tr1 will have a wild-type chromosomal complement?

A)1/2
B)1/3
C)1/4
D)1/9
E)1/81

Question 36

A newly discovered species of dung beetle has 2n = 16 chromosomes.It mates with a closely related beetle species that has 2n = 12 chromosomes.How many chromosomes would there be in an allotriploid beetle produced from this cross?

A)13 or 17
B)19 or 25
C)18 or 24
D)20 or 22
E)36 or 48

Question 37

A man has a condition where all of his gametes undergo nondisjunction of the sex chromosomes in meiosis I, but meiosis II proceeds normally.He mates with a woman who produces all normal gametes.What is the probability that the fertilized egg will develop into a child with Turner syndrome (XO)? Assume that all gametes and zygotes are viable.

A)1/8
B)1/4
C)1/3
D)1/2
E)0

Question 38

What type of organism results from the hybridization of a haploid gamete from one species with a diploid gamete from a different species?

A)Allodiploid
B)Allotriploid
C)Autotriploid
D)Allotetraploid
E)Autotetraploid

Question 39

An explorer stumbled upon a remote valley and found plants that produced a colorful, sweet fruit.Many of these plants were autopolyploid and came in varieties that differed by their ploidy and the size of fruit that was produced.Which of the following plant genomes would MOST likely produce sterile plants?

A)Diploid (2n)
B)Triploid (3n)
C)Tetraploid (4n)
D)Hexaploid (6n)
E)Octaploid (8n)

Question 40

An explorer stumbled upon a remote valley and found plants that produced a colorful, sweet fruit.Many of these plants were autopolyploid and came in varieties that differed by their ploidy and the size of fruit that was produced.Which of the following plant genomes would MOST likely produce the largest fruit?

A)Diploid (2n)
B)Triploid (3n)
C)Tetraploid (4n)
D)Hexaploid (6n)
E)Octaploid (8n)

Question 41

Duchenne muscular dystrophy (DMD)is normally an X-linked recessive human disease affecting boys.Girls afflicted with DMD are rare.Cytogenetic studies of several girls with DMD have in each case revealed that these individuals carry X-autosome translocations.The autosomes vary, but the breakpoint on the X in every case is in band p21, which is the location of the DMD gene.Cytogenetic studies further revealed that in all cells studied in such DMD girls the normal X chromosome exists as a Barr body.How might these observations account for the existence of DMD-affected girls? Why is only the normal X seen as a Barr body?

Question 42

A newly discovered species of dung beetle has 2n = 16 chromosomes.It mates with a closely related beetle species that has 2n = 12 chromosomes.How many chromosomes would there be in an amphidiploid beetle produced from this cross?

A)12
B)14
C)16
D)28
E)12 or 16

Question 43

You are studying two different mutant fish lines (A and

Question 44

Most strains of cultivated bananas were created by crossing plants within and between two diploid species: Musa acuminata (genome = AA)and Musa balbisiana (genome = BB).The Cavendish banana (genome = AAA), the variety most often sold in grocery stores, has what type of genome?

A)Allodiploid
B)Allotriploid
C)Autotriploid
D)Allotetraploid
E)Autotetraploid

Question 45

Isochromosomes have the structure ABC^-CBA (where ^- represents the centromere, and A, B, and C represent wild-type alleles of three different genes).In some cases, such isochromosomes are derived from two copies of one-half of a metacentric chromosome, which has a centromere near its center.For example, a wild-type metacentric chromosome ABC^-DEF might form two distinct isochromosomes, ABC-CBA and FED-DEF.The centromeres of such distinct isochromosomes can be homologous, so that they cause the segregation of the two distinct isochromosomes from each other during meiosis.
a.A mutant of genotype ABC-CBA/FED-DEF is viable.If you cross this mutant with a wild-type individual, what would you expect to be the genotype of the offspring? Would these offspring be viable or not? Explain.
b.What would you expect if you cross this mutant with another individual of genotype ABC-CBA/FED-DEF? Explain.
c.You are given a pericentric inversion mutant in which this same chromosome is of genotype ABD-CEF.In an individual heterozygous for this inversion and a wild-type chromosome there is a crossover between C and the centromere, as follows: Indicate the gametes that would be generated.
d.Assume that the inversion interval is very small, so that both duplications and deletions for this interval (from C to

Question 46

Most strains of cultivated bananas were created by crossing plants within and between two diploid species: Musa acuminata (genome = AA)and Musa balbisiana (genome = BB).Bananas with a genome of AAB are an example of which kind of polyploidy?

A)Allodiploid
B)Allotriploid
C)Autotriploid
D)Allotetraploid
E)Autotetraploid

Question 47

Down syndrome has, in some cases, been found to run in families.Explain the genetic basis for this inherited form of the condition.

Question 48

Explain the genetic basis for sterility in autopolyploid organisms.

Question 49

List the four basic types of chromosome rearrangements.