1. In wolves, black coat color is recessive to the normal grey, and blue eye col

ID: 15727 • Letter: 1

Question

1.
In wolves, black coat color is recessive to the normal grey, and blue eye color is recessive to brown. A black-coated blue eyed male mates with a female who is heterozygous for both traits, and there are 8 pups in the litter.
What are the expected genotoypes of the pups? what are the expected phenotypes?

2.
A man and a woman both have normal color vision, and both have colorblind fathers.
What proportion of their daughters would you expect to be color blind?
What proportion of their sons?

3.
Assume that in the U.S. in 1960, the frequency of the autosomal recessive Tay-Sachs disease among eastern European Jews was 1 per 3600births.
What was the frequency of the Tay-Sachs allel in this population?
In 1961, a woman of polish ancestry whose brother died of Tay-Sachs disease marries a Jewish man of Hungarian ancestry. Assuming that she is a carrier, what is the probability that their first child will have Tay-Sachs disease?

4. In fruit flies, black body (b) is recessive to normal body color (B). In a breeding study, a population of flies is allowed to mate at random. In the population, 3000 flies are homozygous for black body color, and 2000 flies are homozygous for the normal allele.
What is the frequency of each genotype in the F1 generation?
What would the proportion of phenotpyes be?
What is the frequency of the two alleles, B and b, in the F1 generation?

5.
In peas, the dominant seed shape is round and the recessive is wrinkled(w). The dominant trait for pod color is green and recessive is yellow (y). A plant with round seeds and green pods that i heterozygous only for the color trait is crossed with a plant that has wrinkled seeds and yellow pods, and the resulting F1 progeny are selfed(self fertilized).
Write out the P1 genotpes and the F1 and F2 genotypic and phenotypic ratios.
What proportion of the plants with green pods and round seeds from the F2 generation would you expect to be true breeding(i.e. produce only plants with green pods and round seeds)?

Thank you

Explanation / Answer

In wolves, black coat color is recessive to the normal grey, and blue eye color is recessive to brown. A black-coated blue eyed male mates with a female who is heterozygous for both traits, and there are 8 pups in the litter.
What are the expected genotoypes of the pups? what are the expected phenotypes?

black coat color is recessive------------------g

to the normal grey,-------Dominant ------------G

blue eye color is recessive --------b

brown--------------B

. A black-coated blue eyed male mates with a female who is heterozygous for both traits,

black-coated blue eyed male mates-----genotype----------ggbb

female who is heterozygous for both traits,--------- genotype----------GgBb

GAMETES

GB gb

Grey, brown

Gb gb

Grey , blue eye

gB gb

black coat, brown

gb gb

black coat ,blue eye

2.
A man and a woman both have normal color vision, and both have colorblind fathers.
What proportion of their daughters would you expect to be color blind?
What proportion of their sons?

A man and a woman both have normal color vision, and both have colorblind fathers.

man GENOTYPE-----------------XY------------NOT AFFECTED

FAMALE- GENOTYPE----------CARRIER -------XXC

normal color vision

XXC

normal color vision -CARRIER

normal color vision

XCY

color blind MALE

What proportion of their daughters would you expect to be color blind?

ANSWER :ZERO

What proportion of their sons?

50% 0F SONS ARE AFFECTED