Bio Ch 14

1. When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive
phenotype?

0%

25%

50%

75%

100%

2. Huntington's disease is a dominant condition with late age of onset in humans. If one parent has the disease, what is the probability that his or her child will have the disease?

1

3/4

1/2

1/4

0

3. Which describes the ability of a single gene to have multiple phenotypic effects?

Incomplete dominance

Multiple alleles

Pleiotropy

Epistasis

4. Cystic fibrosis affects the lungs, pancreas, the digestive system, and other organs, resulting in symptoms ranging from breathing difficulties to recurrent infections. Which of the following terms best describes this?

Incomplete dominance

Multiple alleles

Pleitropy

Epistasis

5. Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

Prophase I of meiosis

Prophase II of meiosis

Metaphase I of meiosis

Anaphase I of meiosis

Anaphase of mitosis

6. Two characters that appear in 9:3:3:1 ratio in the F2 generation should have which of the following properties?

Each of the traits is controlled by single genes.

The genes controlling the characters obey the law of independent assortment.

Each of the genes controlling the characters has two alleles.

Four genes are involved.

Sixteen different phenotypes are possible.

7. A 1:2:1 phenotypic ratio in the F2 generation of a monohybrid cross is a sign of:

Complete dominance.

Multiple alleles.

Incomplete dominance

Polygenic inheritance

Pleitropy

8. Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

Synapsis of homologous chromosomes

Crossing over

Alignment of tetrads at the equator

Separation of homologs at anaphase

Separation of cells at telophase

9. The flower color trait in radishes is an example of which of the following?

A multiple allelic system

Sex linkage

Codominance

Incomplete dominance

Epistasis

10. Labrador retrievers are black, brown, or yellow. In a cross of a black female with a brown male, results can be either all black puppies, 1/2 black to 1/2 brown puppies, or 3/4 black to 1/4 yellow puppies.

These results indicate which of the following?

Brown is dominant to black.

Black is dominant to brown and yellow.

Yellow is dominant to black.

There is incomplete dominance.

Epistasis is involved.

11. The relationship between genes S and N is an example of

Incomplete dominance

Epistasis

Complete dominance

Pleitropy

Codominance