Deck 4: Gene Mapping in Eukaryotes

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.

Answer 1

D

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.

Answer 2

E

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

Answer 3

E

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.

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

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

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.

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.

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

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.

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.

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.

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

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.

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

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.

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.

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.

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

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.

Question 21

Studies performed on identical twins separated at birth have shown that many phenotypes, such as IQ or alcoholism, are influenced by the person's genotype as well as by their environment.

Question 22

Feather color in chickens is the result of an incompletely dominant gene. The gene responsible for black feathers (B) when homozygous results in a muted color called "Andalusian blue" if combined with an allele for white feathers (b). When the white allele occurs in homozygous condition, a white phenotype results. A gene affecting comb shape (R), which results in a comb called a "rose" comb, is completely dominant over (r), which in homozygous conditions results in a comb called "single." A mating between a black single rooster and white rose hen results in a number of chicks, all of which have identical phenotypes. What is the phenotype and genotype of the chicks?

Question 23

What is the cause of Tay-Sachs disease?

Question 24

In the human ABO blood system, the allele i is dominant to IA and IB.

Question 25

How can a fatal autosomal dominant genetic disorder, like Huntington's disorder, be passed on to the next generation?

Question 26

The 9:6:1 F2 ratio found in fruit shape in summer squash is a deviation from an expected Mendelian ratio. What does this represent?

Question 27

Sex-limited traits are caused by genes that are on sex chromosomes.

Question 28

For a gene with complete dominance, the recessive allele has no effect on the phenotype of a heterozygote.

Question 29

Genes that have a wild-type and multiple mutant forms are said to constitute a gene family.

Question 30

Explain and differentiate among the molecular basis for codominance, incomplete dominance, and complete dominance.

Question 31

Phenylketonuria is an example of a phenotype that is solely influenced by genes.

Question 32

Why is it that males and females who are both heterozygous for the pattern-baldness gene have different phenotypes (males are bald, females are not bald)?

Question 33

In the ABO blood-type system, which genotypes could confer type A blood to a person?

Question 34

What is the number of possible genotypes in a multiple allele series with six alleles? How many of these are homozygous and how many are heterozygous?

Question 35

In chickens, there is a mutant gene called "frizzle" that results in weak, stringy, and easily broken feathers. When a frightfully frizzled fowl is bred to a normal chicken, the offspring are all mildly frizzled. If one breeds two mildly frizzled chickens to each other, the offspring have the phenotypic ratio of 1 normal: 2 mildly frizzled: 1 frightfully frizzled. What is the mode of inheritance of "frizzle?"

Question 36

Human height is a trait affected by both genes and the environment. How is this so?

Question 37

How could a man with blood type A and a woman with blood type B produce a child with blood type O?

Question 38

In a genotype with complete penetrance, less than 100 percent of individuals with a particular genotype exhibit the expected phenotype.

Question 39

Eye color in Drosophila is a case of incomplete dominance and multiple alleles.

Question 40

In a dihybrid cross with independent assortment of the two genes, any deviation from the Mendelian 9:3:3:1 ratio indicates that the phenotype is the product of the interaction of two or more genes.

Question 41

Comb shape in chickens also involves the interaction of two genes, but the F2 generation shows a typical 9:3:3:1 Mendelian ratio. How does this work?