Homework#6 (Tut 14)

Question 1

A litter of mice from the mating of two agouti black parents includes offspring with the following fur colors:

solid color, black
solid color, brown (sometimes called chocolate)
agouti black
agouti brown (sometimes called cinnamon)

What would be the expected frequency of agouti brown offspring in the litter?

Answer 1

3/16

Question 2

Which of the following statements about independent assortment and segregation is correct?

Answer 2

The law of independent assortment requires describing two or more genes relative to one another.

Question 3

Skin color in a certain species of fish is inherited via a single gene with four different alleles. How many different types of gametes would be possible in this system?

Answer 3

4

Question 4

Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height?

Answer 4

a combination of polygenic inheritance and environmental factors

Question 5

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits?

Answer 5

Red shows incomplete dominance over white.

Question 6

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

Answer 6

roan × roan

Question 7

Radish flowers may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The flower color trait in radishes is an example of which of the following?

Answer 7

incomplete dominance

Question 8

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Rh positive is a trait that shows simple dominance over Rh negative. Which of the following is a possible phenotype for the father?

Answer 8

B positive

Question 9

Folk singer Woody Guthrie died of Huntington’s disease, an autosomal dominant disorder. Which statement below must be true?

Answer 9

It is very likely that at least one of Woody Guthrie’s parents also have had the allele for Huntington’s disease.

Question 10

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize the amino acid phenylalanine. This amino acid is not naturally produced by humans. Therefore, the most efficient and effective treatment is which of the following?

Answer 10

Regulate the diet of the affected persons to severely limit the uptake of the amino acid.

Question 11

Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility and death, usually from coronary artery disease, at an average age of approximately 13. Patients, who look very old even as children, do not live to reproduce. Which of the following represents the most likely assumption?

Answer 11

The disorder may be due to mutation in a single protein-coding gene.