Name: _____________________________
Mendelian Genetics Problems
1. Albinism in guinea pigs is inherited as a simple recessive trait. Normal animals
are dark colored, whereas those homozygous for the albino allele (a) are white.
List the expected proportions of the genotypes and phenotypes of the offspring of
two guinea pigs, both of which are heterozygous for albino allele.
2. An albino guinea pig is mated with a normal guinea pig of unknown parentage.
Half of the offspring are albino, half normal. What is the genotype of the normal
parent?
3. The body color of the fruit fly is normally a reddish brown. A recessive allele,
ebony (e), produces a shiny black body. Wing length is normally long, but flies
homozygous for the recessive allele, vestigial wing (v) have dwarfed wings.
Suppose a line of flies is developed that breeds true for the normal phenotypes,
and some of these flies are crossed with black, vestigial winged flies. What is the
genotype of these F1 offspring?
4. These F1 interbreed, producing an F2 generation. List the expected proportions
of the genotypes and phenotypes of these F2 offspring:
5. A single normal-appearing fruit fly is crossed with a black fruit fly having
vestigial wings. If 83 of the resulting offspring are normal, and 96 are black but
have normal wings, what is the genotype of the normal parent?
6. Flax is subject to infection by flax rust. a fungus. In one test plot of flax, about
86% of the plants were found to be susceptible to rust, while the other 14% were
resistant to infection. Resistant plants were chosen from the plot at random and
crossed, producing offspring of which 87% were resistant to infection;
susceptible plants were also crossed and produced offspring that were 100%
susceptible to rust. Assuming this trait is controlled by a single gene, which trait
is dominant?
What experiments could you perform to confirm your guess?
7. Recall that in Mendel’s experiments, purple flowers were dominant to white in
peas. In the following examples, parents with known phenotypes but unknown
genotypes were mated, and produced the tabulated offspring:
Parents
Purple Offspring
White Offspring
a) purple x white
b) purple x purple
c) purple x white
d) purple x purple
79
112
98
132
84
33
0
0
In each case, give the most likely genotypes of the parents: