Mendelian Monohybrid Genetics Problems
1. Human earlobes are either attached or free. Free earlobes are dominant over attached.
Suppose a man with the genotype FF and a woman with attached earlobes produce a
child. What are the possible genotypes of the child? What are the possible phenotypes of
the child?
2. In garden peas, purple flowers are dominant over white flowers. If a white-flowered
garden pea is crossed with a homozygous dominant purple-flowered plant, what is the
genotype of the offspring?
3. In mice, black fur is dominant over brown fur. If a brown mouse and a black mouse
are bred, the resulting progeny are all black. What are the genotypes of the parents?
4. If the F1 offspring are bred with one another, what are the genotypes and the
phenotypes of the F2 generation?
5. The presence of horns on Hereford cattle is controlled by a single gene. The hornless
condition is dominant over the horned condition. A hornless cow was crossed repeatedly
with the same horned bull. The following results were obtained in the F1 progeny:
8 hornless cattle
7 horned cattle
What are the genotypes of the parents?
6. In fruit flies, red eyes are dominant over purple eyes. Two red-eyed fruit flies were
crossed, producing the following offspring:
76 red-eyed flies
24 purple-eyed flies
What is the approximate ratio of red-eyed to purple-eyed flies? What two genotypes give
rise to this ratio? What are the genotypes of the parents? What is the genotypic and
phenotypic ratio of the F1 generation?