Deck 3: Extensions to Mendels Laws

Question 1

A particular flower can be purple, blue, red, or white.Two different pure-breeding white plants are crossed and the F₁ are then crossed to produce an F₂ generation.What might a 9:7 phenotypic ratio in the F₂ indicate?

A)reciprocal recessive epistasis
B)codominance
C)dominant epistasis
D)recessive lethality
E)additivity

Answer 1

A

Question 2

A particular flower can be purple, blue, red, or white.A pure-breeding red plant is crossed with a pure-breeding white one, and the F₁ are then crossed to produce an F₂ generation.Which of the following phenotypic ratios in the F₂ indicate that flower color in these plants is controlled by two genes?

A)2:1
B)3:1
C)1:2:1
D)9:3:4

Answer 2

D

Question 3

What genetic phenomenon might a 2:1 phenotypic ratio indicate?

A)additivity
B)codominance
C)complete dominance
D)recessive epistasis
E)recessive lethal

Answer 3

E

Question 4

If a gene for a trait is monomorphic in a population and two random individuals mate, what would be the most likely phenotypic ratio for that trait in the offspring?

A)2:1
B)1
C)3:1
D)More information is needed

Question 5

In the common daisy, genes A and B control flower color. Both genes have a dominant allele (A or B) and a recessive allele (a or b). At least one copy of each dominant allele is required for flowers to be colorful instead of white.

-Predict the phenotypic ratio of the F₂ progeny of a cross between two white-flowered plants, one homozygous for A and the other homozygous for B.

A)3 colorful : 1 white
B)9 colorful : 7 white
C)9 white : 7 colorful
D)15 white : 1 colorful
E)15 colorful : 1 white

Question 6

In rats, the P gene allele for pigmentation (P) is dominant to the allele for albinism (p). The B gene allele for black pigmentation (B) is dominant to the allele for cream pigmentation (b). The pp homozygous recessive genotype is epistatic to any allele combination at gene B.

-Predict the phenotypic ratio of the F₂ progeny of a parental cross between a pure-breeding black rat and an albino that is also homozygous for cream.

A)1 black: 2 cream: 1 albino
B)9 black: 3 cream: 4 albino
C)9 black: 7 albino
D)12 black: 3 cream: 1 albino
E)15 black: 1 albino

Question 7

The inheritance pattern of daisy flower color provides an example of what type of gene interaction?

A)additivity
B)recessive epistasis
C)reciprocal recessive epistasis
D)dominant epistasis
E)redundancy

Question 8

A disease is caused by homozygosity for the g allele (G is the corresponding wild-type allele).However, the penetrance of the disease is 75%.Two individuals known to be heterozygotes have a child.What is the probability that the child exhibits the disease?

A)1/4
B)3/4
C)1/8
D)3/16
E)9/16

Question 9

Two alleles of gene C control hair color in horses: C¹ and C².Horses homozygous for allele C¹ are red, heterozygotes are yellow, and C² homozygotes are cream.In the offspring of matings between heterozygotes, what phenotypic ratio is expected?

A)2 yellow: 1 red
B)3 red: 1 cream
C)1 red: 2 yellow: 1 cream
D)all red
E)9 red: 3 yellow: 4 cream

Question 10

Two alleles of gene C control hair color in horses: C¹ and C².Horses homozygous for allele C¹ are red, heterozygotes are yellow, and C² homozygotes are cream.What type of allele interaction is described?

A)pleiotropy
B)complete dominance
C)incomplete dominance
D)recessive lethality
E)codominance

Question 11

In the common daisy, genes A and B control flower color. Both genes have a dominant allele (A or B) and a recessive allele (a or b). At least one copy of each dominant allele is required for flowers to be colorful instead of white.

-Predict the genotypes and phenotypes of the F₁ progeny of a cross between two white-flowered plants, one homozygous for A and the other homozygous for B.

A)AA bb, white
B)aa BB, white
C)Aa Bb, colorful
D)Aa Bb, white
E)aa bb, colorful

Question 12

Which genotypic ratio indicates a recessive lethal allele when two heterozygotes are mated?

A)2:1
B)3:1
C)1:2:1
D)1:1
E)4:1

Question 13

A pure-breeding fruit fly with curled wings mates with a pure-breeding fruit fly with normal (straight)wings.The F₁ mate with each other to produce an F₂ generation that consists of 160 flies with curled wings and 80 with straight wings.What can you infer from this observation?

A)Curled wings is a recessive trait.
B)The dominant curled wing allele is also a recessive lethal.
C)Wing shape is controlled by two codominant alleles.
D)Two interacting genes determine wing shape.
E)All of the hybrid F₁ flies had straight wings.

Question 14

A particular flower can be purple, blue, red, or white.A pure-breeding purple plant is crossed with a pure-breeding white plant and the F₁ are then crossed to produce an F₂ generation.What might a 9:3:4 phenotype ratio in the F₂ indicate?

A)reciprocal recessive epistasis
B)codominance
C)dominant epistasis
D)recessive epistasis
E)additivity

Question 15

If a trait is controlled by two codominant alleles of one gene, what phenotypic ratio is expected in the offspring of a mating of two heterozygotes?

A)2:1
B)3:1
C)1:2:1
D)1:1
E)4:1

Question 16

ABO blood type demonstrates which of the following inheritance patterns? (Select all that apply. )

A)complete dominance
B)incomplete dominance
C)codominance
D)pleiotropy
E)three genes are involved

Question 17

What can explain the phenomenon where the same genotype might give rise to different phenotypes?

A)pleiotropy
B)codominance
C)incomplete dominance
D)complete dominance
E)penetrance and expressivity

Question 18

If a phenotype is controlled by the genotypes at two different loci, a possible interaction between alleles of these genes can be called

A)epistasis.
B)epigenetics.
C)dominance.
D)codominance.
E)incomplete dominance.

Question 19

Which ratio would indicate that a phenotype is controlled by multiple genes?

A)3:1
B)2:1
C)1:2:1
D)9:3:3:1.

Question 20

In rats, the P gene allele for pigmentation (P) is dominant to the allele for albinism (p). The B gene allele for black pigmentation (B) is dominant to the allele for cream pigmentation (b). The pp homozygous recessive genotype is epistatic to any allele combination at gene B.

-Predict the genotypes and phenotypes of the F₁ progeny of a cross between a pure-breeding black rat and an albino that is also homozygous for cream.

A)PP BB, black
B)Pp Bb, black
C)Pp Bb, albino
D)pp Bb, albino

Question 21

Two pure-breeding phlox plants were crossed, one with dark-blue flowers and the other with pink flowers. The F1 generation all had dark-blue flowers. When the F1 were crossed with each other, the F2 generation consisted of 176 plants: 101 with dark-blue flowers, 33 with light-blue flowers, 30 with red flowers, and 10 with pink flowers

-What progeny types would result from crossing a homozygous plant with light-blue flowers to a homozygous plant with red flowers?

A)all would be dark blue
B)all would be red
C)1 light blue : 1 red
D)9 dark blue : 3 light blue : 3 red : 1 pink

Question 22

Two pure-breeding phlox plants were crossed, one with dark-blue flowers and the other with pink flowers. The F1 generation all had dark-blue flowers. When the F1 were crossed with each other, the F2 generation consisted of 176 plants: 101 with dark-blue flowers, 33 with light-blue flowers, 30 with red flowers, and 10 with pink flowers

-How is flower color controlled in phlox?

A)one gene with four alleles
B)one gene with two codominant alleles
C)two genes whose alleles interact additively
D)two genes with dominant epistasis

Question 23

In some flowers, a purple pigment is synthesized from a red precursor pigment.In the absence of all pigment, flowers are white.A pure-breeding plant with red flowers was crossed to a pure-breeding plant with white flowers.All of the F₁ plants had white flowers.The F₁ plants were crossed to each other, and the F₂ consisted of 165 plants: 123 with white flowers, 32 with purple flowers, and 11 with red flowers.How do these results suggest that flower color is determined?

A)One gene with two alleles exists and heterozygotes have a different phenotype than either homozygote.
B)The dominant allele of one gene masks the effect of a second gene.
C)The recessive allele of one gene masks the effect of a second gene.
D)A dominant allele of two genes is necessary for purple flowers.
E)A dominant allele of either of two genes is sufficient for purple flowers.

Question 24

In primroses, the dominant allele of gene K is necessary to synthesize blue flower pigment. Blue pigment synthesis is inhibited by a dominant allele of gene D. In other words, plants with the genotype K- D- will not produce pigment (and their flowers will be white) because of the presence of the D allele.

-If two dihybrid plants (Kk Dd)are crossed, what is the ratio of blue to white offspring in the progeny?

A)3 blue: 1 white
B)7 blue: 9 white
C)4 blue: 12 white
D)3 blue: 13 white
E)1 blue: 15 white

Question 25

What type of gene interaction determines flower color in primroses?

A)one gene with two completely dominant alleles
B)two-genes with recessive epistasis
C)two redundant genes
D)two genes with dominant epistasis

Question 26

Achondroplasia is a form of dwarfism in humans. It is caused by a mutant allele of the fibroblast growth factor receptor gene (FGFR) that produces an overactive protein. Having one copy of the mutant allele results in dwarfism. Two copies of the mutant allele results in death before birth.

-Based in this information, what can you infer about the inheritance of the FGFR alleles?

A)The mutant FGFR allele is pleiotropic.
B)Some achondroplastic dwarfs are heterozygous for the mutant allele and some are homozygous.
C)The wild-type and mutant FGFR alleles are codominant.
D)The mutant FGFR allele shows incomplete penetrance.

Question 27

Some multifactorial traits are determined by many interacting genes, each of which may have several alleles.If such a trait is measured in a population, what phenotypic pattern is expected?

A)All individuals will have the same phenotype.
B)Two types of individuals will exist, and most will have the dominant phenotype.
C)Different individuals will each have one of a few discrete phenotypes.
D)The population will have continuous variation in phenotypic expression.

Question 28

Achondroplasia is a form of dwarfism in humans. It is caused by a mutant allele of the fibroblast growth factor receptor gene (FGFR) that produces an overactive protein. Having one copy of the mutant allele results in dwarfism. Two copies of the mutant allele results in death before birth.

-If two people with achondroplasia have a child together, what is the probability that their child will also have achondroplasia?

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

Question 29

A particular flower can be purple, blue, red, or white.A pure-breeding purple plant is crossed with a pure-breeding white plant and the F₁ are then crossed to produce an F₂ generation.Which phenotypic ratio in the F₂ may indicate that flower color in these plants is controlled by two genes that interact additively?

A)3:1
B)1:2:1
C)9:3:3:1
D)9:3:4
E)15:1