BIOL 360 – You are studying a gene that controls

11 Jun BIOL 360 – You are studying a gene that controls

Question
Question 5

You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However the L allele is only 60% penetrant. You cross two heterozygous giraffes. What proportion of offspring would you expect to exhibit the long ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.

a) 0.60

b) 0.75

c) 0.45

d) 0.40

e) 0.55

Question 6

Suppose that pointy earlobes is caused by a recessive trait, but it appears in only 70% of homozygous recessive individuals. What is the maximum probability that a man with pointy earlobes and a woman with round earlobes will have a child with pointy earlobes?

a) 0.05

b) 0.25

c) 0.10

d) 0.33

e) 0.35

Question 7

In rabbits, an allelic series helps to determine coat color: f (full color), ch (chinchilla; gray color), hi (Himalayan; white with black extremities), and w (albino; all white). The dominance hierarchy can be summarized as f > ch > hi > w. Indicate the phenotypic ratios expected from the cross f/ch x f/hi.

a) 1 chinchilla:1 Himalayan

b) 1 full color:1 chinchilla

c) 3 full color:1 chinchilla

d) 2 full color:1 Himalayan:1 albino

e) 1 full color:1 Himalayan

Question 12

In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are self-crossed, the F2 occur in the ratio 9 blue:3 pink:4 white. The genotype that produces white is ww. The presence of one W allele allows pink or blue color to occur. The alleles at the hypostatic locus are B (blue) and b (pink). What is the genotype of the white parent?

a) Bb Ww

b) bb WW

c) bb Ww

d) Bb ww

e) BB ww

Question 15

In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are self-crossed, the F2 occur in the ratio 9 blue:3 pink:4 white. The genotype that produces white is ww. The presence of one W allele allows pink or blue color to occur. The alleles at the hypostatic locus are B (blue) and b (pink). What is the genotype of the pink parent?

a) bb Ww

b) bb WW

c) BB ww

d) Bb ww

e) Bb Ww

Question 19

You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However, the L allele is only 60% penetrant. You cross two heterozygous giraffes. What proportion of offspring would you expect to exhibit the short ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.

a) 0.55

b) 0.25

c) 0.40

d) 0.45

e) 0.60

Question 21

Which of the following is an example of gene interactions____

a) incomplete dominance.

b) codominance.

c) epistasis.

d) environmental influence on phenotype.

e) complete dominance.

Question 22

A character is determined by three alleles (M,N,O). Which of the following is the most reasonable statement about their dominance relative to each other___ ?

a) more than two alleles, each contributes to a third of the associated phenotype.

b) if allele M is dominant over N, then it is also dominant over O.

c) allele M could be dominant over N, but recessive to O.

d) if allele M shows complete dominance over N, it will show complete dominance over O.

Question 23

Which of the following are CORRECT about phenocopies ?

a) Phenocopy is when a given mutation can be seen only under specific environmental conditions.

b) Phenocopy is a phenotype produced by identical copies of an allele (i.e. a homozygous)

c) Phenocopy is a phenotype produced by an environmental effect that mimics a phenotype produced by a given genotype.

d) Phenocopy can make a wild-type look like a mutant, or make a mutant look like a wild-type.

Question 28

The probability that two parents with a family of four will have one girl and three boys (in no particular order) is

a) 1/16

b) 1/2

c) 1/4

d) 1/32