Deck 14: Mendelian Genetics

Question 1

Which of the following mutations would most likely be a lethal mutation?

A) Translocation
B) Deletion
C) Point mutation
D) Duplication
E) All of the above

Answer 1

B

Question 2

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

Answer 2

B

Question 3

A human cell containing two sets of 23 chromosomes is

A) euploid.
B) polyploid.
C) aneuploid.
D) diploid.
E) haploid.

Answer 3

A

Question 4

Nondisjunction of chromosomes may result in

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

Question 5

What kind of analysis allows you to visualize an individual's chromosomal makeup?

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

Question 6

Which of the following traits is determined by programmed transposition?

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

Question 7

Seedless bananas are produced from

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

Question 8

The condition resulting from a trisomy of chromosome 21 is

A) Down syndrome.
B) Turner syndrome.
C) Cri du chat syndrome.
D) Klinefelter syndrome.
E) Reye syndrome.

Question 9

Most monoploid individuals do not survive because

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

Question 10

A ________ inversion involves the centromere.

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

Question 11

What is the genetic consequence of a homozygous translocation?

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

Question 12

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

A) Duplication
B) Translocation
C) Deletion
D) Inversion
E) All may revert to wild-type.

Question 13

A monosomic cell would produce gametes with how many chromosomes?

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

Question 14

A dicentric chromosome has two

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

Question 15

If a horse and a donkey are mated, the resulting hybrid animal will be

A) haploid and fertile.
B) polyploid and sterile.
C) diploid and sterile.
D) polyploid and fertile.
E) haploid and sterile.

Question 16

In some insect larvae, polytene chromosomes are produced when

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

Question 17

The chemical colchicine may be used

A) for experimental induction of mutant polyploid individuals.
B) for experimental induction of mutant aneuploid individuals.
C) to induce chromosomal duplications in experimental cell lines.
D) to prevent nondisjunction in cell cultures.
E) to induce chromosomal deletions in experimental cell lines.

Question 18

In familial Down syndrome resulting from Robertsonian translocation,

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

Question 19

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

Question 20

A heterozygous chromosomal inversion can be detected

A) by observing a decrease in the number of viable progeny following genetic crosses.
B) by cytogenetic observation of loops in chromosomes.
C) through genetic studies indicating a decrease in the frequency of recombination between genes.
D) Both A and B
E) All of the above

Question 21

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 22

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

Question 23

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

Question 24

Give an example of a human disorder caused by a change in chromosomal structure and an example of a human disorder caused by a change in chromosomal number.

Question 25

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

Question 26

A nullisomic human cell would contain 22 pairs of chromosomes.

Question 27

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

Question 28

Explain and give an example of gene amplification.

Question 29

A tetraploid cell contains four chromosomes.

Question 30

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

Question 31

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

Question 32

What causes fragile X syndrome, what condition does it confer, and who is more likely to exhibit the condition, males or females?

Question 33

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

Question 34

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

Question 35

What will be the result if a normal gamete fuses with a gamete from the previous question with two chromosome sets?

Question 36

For eukaryotic organisms, polyploidy is always a lethal condition.

Question 37

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 with red and white. Explain why.

Question 38

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

Question 39

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

Question 40

How is hybrid sterility overcome in allopolyploid plants?

Question 41

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 42

What are the gametic consequences of a paracentric inversion with a single crossover event during meiosis compared to that of a pericentric inversion with single crossover?

Question 43

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?