Question 1

In a multiple allelic system for eye color in Drosophila, the phenotypic expression of the alleles depends on
A) the sex of the fly.
B) the interaction of alleles from two different genes.
C) the temperature at which the flies are grown.
D) how much pigment is produced by the alleles present.
E) both A and B.

Accepted Answer

The phenotypic expression of eye color in Drosophila in a multiple allelic system is determined by the amount of pigment produced by the alleles present.

Question 2

The death of an organism may be caused by
A) an epistatic allele.
B) mutation in an essential gene.
C) a lethal allele.
D) incomplete penetrance of an allele.
E) both B and C.

Accepted Answer

A mutation in an essential gene or a lethal allele can cause the death of an organism.

Question 3

A and B antigens in human blood are produced by the conversion of ________ by the addition of a sugar group.
A) α-N-acetylgalactosamine
B) the Bombay antigen
C) anti-A and anti-B antibodies
D) anti-O antibodies
E) the H antigen

Accepted Answer

The A and B antigens in human blood are produced by the conversion of the H antigen through the addition of specific sugar groups.

Question 4

The agouti coat color in mice is the result of recessive epistasis, where the F2 phenotypic ratio is
A) 9:3:4.
B) 9:7.
C) 9:3:3:1.
D) 3:1.
E) 9:6:1.

Accepted Answer

Recessive epistasis typically results in a 9:3:4 phenotypic ratio in the F2 generation, where one gene's recessive alleles mask the effects of another gene.

Question 5

Which of the following will result in modifications to the expected Mendelian ratios?
A) Incomplete penetrance
B) Incomplete dominance
C) Epistasis
D) Gene interaction
E) All of the above

Accepted Answer

All of the above factors can alter the expected Mendelian ratios by affecting how traits are expressed or interact with each other.

Question 6

If the offspring above was crossed with one another, what would be the ratio of phenotypes in the F2 generation?
A) All pink B
B) 3 red: 1 white
C) 1 red: 1 white
D) 1 red: 1 pink: 1 white
E) 1 red: 2 pink: 1 white

Accepted Answer

The answer of If the offspring above was crossed with...

Question 7

The distinctive fur pattern of Siamese cats results when genes that are responsible for the coat color are influenced by
A) X-inactivation.
B) age.
C) gender.
D) temperature.
E) other genes.

Accepted Answer

The coat color of Siamese cats is influenced by temperature-sensitive enzymes, which cause darker fur in cooler areas of the body.

Question 8

Comb shape in chickens is controlled by
A) the epistatic interaction of two genes, resulting in two different phenotypes.
B) the interaction of three alleles and codominance, resulting in four different phenotypes.
C) the interaction of two genes with complete dominance, resulting in four different phenotypes.
D) one gene with incomplete dominance, resulting in three different phenotypes.
E) none of the above.

Accepted Answer

Comb shape in chickens is controlled by the interaction of two genes, each with complete dominance, resulting in four different phenotypes: single, rose, pea, and walnut.

Question 9

A cat that is homozygous recessive for the Manx gene has which of the following phenotypes?
A) No tail
B) Normal tail
C) Dead
D) Dark fur at the extremities
E) Tortoiseshell coat

Accepted Answer

Cats that are homozygous recessive for the Manx gene (mm) typically do not survive, as this genetic combination is lethal.

Question 10

Novel phenotypes may arise when
A) two allelic pairs in a dihybrid cross-affect the same phenotypic characteristic.
B) there is incomplete dominance between two alleles of the same gene.
C) there is a large norm of reaction for the genotype.
D) Both A and B
E) environmental factors influence gene expression.

Accepted Answer

Novel phenotypes can arise when two allelic pairs in a dihybrid cross affect the same phenotypic characteristic (A) and when there is incomplete dominance between two alleles of the same gene (B). Both scenarios can lead to new phenotypic expressions not seen in the parent generation.

Question 11

Individuals with neurofibromatosis may have a range of phenotypes, from pigment spots on the skin to tumorlike growths. This is an example of
A) incomplete penetrance.
B) gene magnification.
C) age of onset.
D) X-inactivation.
E) variable expressivity.

Accepted Answer

Variable expressivity refers to the range of signs and symptoms that can occur in different people with the same genetic condition, as seen in neurofibromatosis.

Question 12

For traits that show incomplete dominance, the phenotype of a heterozygote is
A) the same as the homozygous dominant phenotype.
B) completely different from either the homozygous dominant or recessive phenotype.
C) the same as the homozygous recessive phenotype.
D) a mosaic of the homozygous dominant and the homozygous recessive phenotypes.
E) intermediate between the homozygous dominant and the homozygous recessive phenotypes.

Accepted Answer

In incomplete dominance, the heterozygote exhibits a phenotype that is intermediate between the phenotypes of the homozygous dominant and homozygous recessive individuals.

Question 13

A person with type B blood could receive a transfusion of blood from someone with blood type
A) O.
B) AB.
C) B.
D) Both A and C
E) All of the above

Accepted Answer

The answer of A person with type B blood could...

Question 14

The child of a woman who was infected with rubella during pregnancy may show a disorder that mimics a genetic defect. The disorder is known as a
A) environmental disorder.
B) novel phenotype.
C) phenocopy.
D) variably expressed trait.
E) phenotype.

Accepted Answer

A phenocopy is an environmentally caused trait that mimics a genetic disorder, such as when rubella infection during pregnancy causes birth defects similar to genetic conditions.

Question 15

Dogs have one gene that controls how much melanin is produced, a second gene that controls whether melanin is deposited in the fur, and a third gene that controls whether melanin is produced at all. What do you call the interaction of these three genes?
A) Duplicate-recessive epistasis
B) Codominance
C) Incomplete dominance
D) Multiple allele system
E) Albinism

Accepted Answer

This interaction is an example of duplicate-recessive epistasis, where two recessive alleles at either of two loci can suppress a phenotype, such as melanin production and deposition in this case.

Question 16

Two true-breeding mutant strains of Drosophila have black body color instead of the wild-type gray yellow. When the two strains are crossed, all the F1 flies have wild-type body color. How can these data be interpreted?
A) Recombination occurred.
B) The mutations involved are on two different genes.
C) Complementation occurred.
D) Both B and C
E) A new mutation occurred in all the offspring.

Accepted Answer

The F1 flies having wild-type body color suggests that the mutations are in different genes, allowing for complementation to occur, which restores the wild-type phenotype.

Question 17

Autosomal traits that appear only in one gender are
A) sex limited.
B) sex influenced.
C) sex inhibited.
D) sex linked.
E) all of the above.

Accepted Answer

Sex-limited traits are autosomal traits that are expressed in only one gender due to hormonal differences, despite being present in both.

Question 18

A true-breeding red-flowered plant is fertilized by a true-breeding white-flowered plant and produces all pink-flowered offspring. This is a case of
A) incomplete dominance.
B) blending inheritance.
C) multiple alleles for flower color.
D) codominance.
E) epistasis.

Accepted Answer

This is a case of incomplete dominance, where the heterozygous offspring have a phenotype that is intermediate between the two homozygous parents, resulting in pink flowers from red and white parents.

Question 19

In an interacting gene pair, the gene whose expression is masked by another gene is the ________ gene.
A) homostatic
B) limnostatic
C) hyperstatic
D) hypostatic
E) epistatic

Accepted Answer

The hypostatic gene is the one whose expression is masked by the presence of another gene, known as the epistatic gene.

Question 20

A person who is known to have a particular genotype does not show the phenotype specified by the gene. This is an example of
A) epistasis.
B) phenotype switching.
C) sex reversal.
D) incomplete dominance.
E) incomplete penetrance.

Accepted Answer

Incomplete penetrance occurs when individuals with a particular genotype do not express the expected phenotype, meaning the gene is not fully penetrant in all individuals.

Quiz 4: Gene Mapping in Eukaryotes

In a multiple allelic system for eye color in Drosophila, the phenotypic expression of the alleles depends on

The death of an organism may be caused by

A and B antigens in human blood are produced by the conversion of ________ by the addition of a sugar group.

The agouti coat color in mice is the result of recessive epistasis, where the F2 phenotypic ratio is

Which of the following will result in modifications to the expected Mendelian ratios?

If the offspring above was crossed with one another, what would be the ratio of phenotypes in the F2 generation?

The distinctive fur pattern of Siamese cats results when genes that are responsible for the coat color are influenced by

Comb shape in chickens is controlled by

A cat that is homozygous recessive for the Manx gene has which of the following phenotypes?

Novel phenotypes may arise when

Individuals with neurofibromatosis may have a range of phenotypes, from pigment spots on the skin to tumorlike growths. This is an example of

For traits that show incomplete dominance, the phenotype of a heterozygote is

A person with type B blood could receive a transfusion of blood from someone with blood type

The child of a woman who was infected with rubella during pregnancy may show a disorder that mimics a genetic defect. The disorder is known as a

Dogs have one gene that controls how much melanin is produced, a second gene that controls whether melanin is deposited in the fur, and a third gene that controls whether melanin is produced at all. What do you call the interaction of these three genes?

Two true-breeding mutant strains of Drosophila have black body color instead of the wild-type gray yellow. When the two strains are crossed, all the F1 flies have wild-type body color. How can these data be interpreted?

Autosomal traits that appear only in one gender are

A true-breeding red-flowered plant is fertilized by a true-breeding white-flowered plant and produces all pink-flowered offspring. This is a case of

In an interacting gene pair, the gene whose expression is masked by another gene is the ________ gene.

A person who is known to have a particular genotype does not show the phenotype specified by the gene. This is an example of