In the following questions, assign letters to the alleles and show your punnet squares
1. In cats, long hair is recessive to short hair. A true-breeding (homozygous) short-haired male is mated to a long-haired female. What will their kittens look like?
2. Two cats are mated. One of the parent cats is long-haired (recessive allele). The litter which results contains two short-haired and three long-haired kittens. What does the second parent look like, and what is its genotype?
3. Mrs. And Mr. Smith both have widow’s peaks (dominant). Their first child also has a widow’s peak, but their second child doesn’t. Explain why.
4. Mr. and Mrs. Jones have six children. Three of them have attached earlobes (recessive) like their father, and the other three have free earlobes like their mother. What are the genotypes of Mr. and Mrs. Jones and of their numerous offspring?
5. Mr. and Mrs. Anderson both have tightly curled hair. (The hair form gene shows incomplete dominance. There are two alleles, curly and straight. The heterozygote has wavy hair.) Draw the punnet square
6. Two wavy haired people (one male and one female) marry and have eight children. Of these eight, how many would you expect to be curly haired, how many wavy haired and how many straight haired, assuming that the family follows the expected statistically predicted pattern? Suppose you examine the actual children and discover that three of the eight have curly hair. Explain how this could have happened
7. Basic body color for horses is influenced by several genes, on of which has several different alleles. Two of these alleles—the chestnut (dark brown) allele and a diluting (pale cream) allele (often incorrectly called ‘albino’)—display incomplete dominance. A horse heterozygous for these two alleles is a palomino (golden body color with flaxen mane and tail). Is it possible to produce a herd of purebreeding palomino horses? Why or why not? Work the Punnett’s square for mating a palomino to a palomino and predict the phenotypic ratio among their offspring.
8. There is a genetic disease called Tay Sachs disease, which is fatal to infants within the first five years of life. This disease is caused by a recessive allele of a single gene. Why does this disease persist, even though it is invariably fatal long before the afflicted individual reaches reproductive age? (In other words, why doesn’t the allele for Tay Sachs disease simply disappear?)
9. About 80% of the human population can taste the chemical phenolthiocarbamide (PTC), while the other 20% can’t. This characteristic is governed by a single gene with two alleles, a tasting allele and a nontasting allele. What does this statistic tell us about which allele (tasting or non-tasting) is dominant?
sex linkage:
10. Earl has normal color vision, while his wife Erma is colorblind. . Colorblindness is an X-linked trait, and the normal allele is dominant to the colorblindness allele. If they have a large family, in what ways should the colorblindness trait affect their children?
11. Ethan is colorblind. His wife, Edna, is homozygous for the normal color vision allele. If they have eight children, how man of them would you expect to be colorblind? Using Punnett’s squares, derive and compare the genotypic and phenotypic ratios expected for the offspring of this marriage and those expected for the offspring of the marriage described in III.3.
12. Marian’s father is colorblind, as is her maternal grandfather (her mother’s father). Marian herself has normal color vision. Marian and her husband, Martin, who is also colorblind, have just had their first child, a son they have named Mickey.
Please answer the following questions about this small family.
a. What is the probability that this child will be colorblind?
b. Three sources of the colorblindness allele are mentioned in this family. If Mickey is colorblind, from which of these three men (Marian’s grandfather, Marian’s father, or Martin) did he inherit the allele?
c. Using proper pedigree format, diagram the available information about the four generations of this family described, assuming that Mickey is colorblind.
d. If Martin were not colorblind, how would this affect the prediction about Mickey?
Multiple alleles:
13.In a particular family, one parent has Type A blood, the other has Type B. They have four children. One has Type A, one has Type B, one has Type AB, and the last has Type O. What are the genotypes of all six people in this family? NOTE: The ABO blood type gene has three alleles. I A and I B are codominant; i (for Type O) is recessive to both.
These questions are from a selection from this website
https://www.soinc.org/sites/default/files/uploaded_files/2020_HEREDITY_PRACTICE_PROBLEMS_SOLUTIONS_0.pdf
