University of Tennessee

BIO 240

Quiz 3 Feb 15

Q.1)You are looking at the color of feathers in ducks and find that yellow ducks (Y) are dominant to green ducks (y). However, a second gene, H, controls whether the color will be expressed in the feathers. If the duck is hh, the duck will always be white, because the pigment does not go into feathers. What ratio of phenotypes would you expect following a dihybrid cross?

a)    15:1

b)   12:3:1

c)    13:3

d)    9:6:1

e)    9:3:4

Q. 2 In Labrador retrievers, the coat color is controlled by gene interaction in which homozygosity for a recessive allele can mask the phenotypic expression of a second gene. This genetic interaction is known as                                                .

1. dominant gene interaction
2. dominant suppression
3. dominant epistasis
4. recessive epistasis

 

Q. 3 In complementary gene interactions, two genes work in tandem to produce a particular phenotype. Functional copies of both genes are required to produce the phenotype. What phenotypic ratios would be expected among the progeny of a dihybrid cross involving dominant and recessive alleles for two such complementary genes (i.e., AaBb x AaBb)?

a)    9:3:3:1

b)   9:7

c)    9:3:4

d)   15:1

 

Q. 4 Complementation tests of distinct recessive mutants, 1 through 8, produce the data in the matrix below. A plus (+) indicates complementation, meaning the phenotype of the combined alleles is wild type, and a minus (-) indicates a failure to complement meaning that a mutant phenotype results. Assume that the missing mutant combinations would yield data consistent with the entries that are shown.

 

1     2     3     4     5     6     7     8

1             -                    +

2                                   -

3             -                     -

4            +

5                    +      -

6             +

7

8

 

How many complementation groups are formed by these eight mutants?

 

5

4

3

6

2

Q. 5 In genetic complementation testing, crosses are performed between pure-breeding strains for recessive mutations that confer the same mutant phenotype. If the two mutations are

in different genes, then what phenotypic ratios would be expected among the progeny?

 

1. All of the F₁ progeny would display the mutant phenotype associated with the parents.
2. All of the F₁ progeny would be wild type.
3. All of the F₁ progeny would display a novel mutant phenotype that differs from that of the parents.
4. There will be a 1:1 ratio of mutant to wild type.

 

Q. 6   Syntenic genes can assort independently when                   .

 

1. they are far apart on a chromosome and crossing over occurs frequently between the genes
2. they are located on different chromosomes
3. crossing over occurs rarely between the genes
4. they are far apart on a chromosome and crossing over occurs very rarely between the genes
5. they are very close together on a chromosome

 

Q. 7 Genetic linkage leads to the production of a significantly greater than expected number of gametes containing chromosomes with                  .

 

1. allele combinations that are different from parental combinations
2. dominant alleles
3. mutant alleles
4. parental combinations of alleles
5. recessive alleles

 

Q. 8 In fruit flies, red eyes (pr+_) are dominant to purple eyes (prpr) and normal wings (vg⁺_) are dominant to vestigial wings (vgvg). The genes are located on the same chromosome. A pure breeding red-eyed fly with vestigial wings was crossed with a pure-breeding purple-eyed fly with normal wings. All of the F1 progeny had a WT phenotype. Which of the following represents the arrangement of alleles on the F1's chromosome?

 

1. prpr+/vgvg+
2. prvg/prvg
3. pr+vg/prvg+
4. prvg/pr+vg+
5. pr+vg+/pr+vg+

 

Q. 9 What is the term for chromosomes that do not reshuffle the alleles of linked genes

1. homologous chromosomes
2. nonhomologous chromosomes
3. parental chromosomes
4. recombinant chromosomes