Question 1

Which genetic phenomenon explains why the yellow Labrador retriever in the image appears yellow, even though it may carry alleles for black or brown pigment production?

Accepted Answer

Recessive epistasis

Question 2

A cross between two true-breeding white-flowered pea plants produces all purple-flowered F1 offspring. What does this result indicate about the genetic basis of flower color in these strains?

Accepted Answer

The parents have mutations in different genes that complement each other

Question 3

In a dihybrid cross involving two genes that both contribute to the same trait, the F2 generation shows a 9:3:3:1 phenotypic ratio. What does this suggest about the genetic interaction?

Accepted Answer

There is no gene interaction; both genes assort independently

Question 4

Which of the following best describes duplicate recessive epistasis, as seen in the genetic control of flower color in peas?

Accepted Answer

Recessive alleles at either locus result in the same mutant phenotype

Question 5

A cross between two pepper plants, Y+Y+ C+C+ (red) and yy cc (cream), produces F1 plants that are all red. If these F1 plants are self-crossed, what phenotypic ratio is expected in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 6

In the F2 generation of the pepper plant cross described above, what is the expected ratio of red, peach, orange, and cream phenotypes?

Accepted Answer

$$9$$ red : $$3$$ peach : $$3$$ orange : $$1$$ cream

Question 7

Which of the following is an example of a conditional allele, as illustrated by the rabbits in the images?

Accepted Answer

An allele that is only expressed at certain temperatures

Question 8

A geneticist finds six different white-flowered mutants in pea plants. Crosses between some pairs produce purple F1 offspring, while others remain white. What genetic test is being performed?

Accepted Answer

Complementation test

Question 9

Which of the following modified dihybrid ratios is associated with duplicate dominant epistasis?

Accepted Answer

$$15:1$$

Question 10

In the case of Labrador retriever coat color, which genotype results in a yellow coat regardless of the B gene alleles?

Accepted Answer

$$B- ee or$$ $$bb ee$$

Question 11

Which of the following best explains why most human traits, such as height, do not follow simple Mendelian inheritance?

Accepted Answer

Most traits are controlled by multiple genes (polygenic)

Question 12

A mouse with genotype $$aa B-$$ for two coat color genes displays a different color than $$A- B-. $$What type of gene interaction could explain this?

Accepted Answer

Epistasis

Question 13

Which of the following statements about the complementation test is correct?

Accepted Answer

If two mutants fail to complement, they have mutations in the same gene

Question 14

Which phenotypic ratio would you expect in the F2 generation if two genes exhibit recessive epistasis?

Accepted Answer

$$9:3:4$$

Question 15

In a genetic pathway, two enzymes are required to produce a pigment. If either enzyme is nonfunctional, no pigment is produced. What is the expected F2 phenotypic ratio from a dihybrid cross?

Accepted Answer

$$9:7$$

Question 16

Which of the following is NOT a modification to simple Mendelian inheritance?

Accepted Answer

Complete dominance with 100% penetrance

Question 17

A plant with genotype $$C- pp$$ for flower color genes produces white flowers. What does this indicate about the genetic pathway?

Accepted Answer

Both C and P are required for pigment production

Question 18

Which of the following best describes the molecular explanation for the 9:3:3:1 ratio in multigenic traits such as pepper color?

Accepted Answer

Both genes encode enzymes required for pigment biosynthesis

Question 19

Which of the following is an example of a real-world application of gene interaction analysis?

Accepted Answer

Determining the number of genes involved in a metabolic pathway by complementation testing

Lecture 5

Study Guide - Practice Questions

Study Guide - Flashcards