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Single Trait Crosses – Practice Questions
In pea plants, round peas are dominant over wrinkled. Predict the genotypes and phenotypes that will be
found if a plant homozygous for round peas (RR) and a plant homozygous for wrinkled peas (rr) are
crossed.
In tomatoes, red fruit (R) is dominant over yellow fruit (r). If a heterozygous red fruit is crossed with a
yellow fruit,
a) What is the appearance of the F1 generation?
b) What are the genotypes of the F2 generation if two plants from the F1 generation are crossed?
c) What are the phenotypes of the F2 generation?
In cattle, horns (h) are recessive to hornless (H). If two homozygous cattle, one hornless and the other
horned, are crossed, what are the genotypes and phenotypes of the first generation?
As a reward for being a good student, Mrs. Renkema gives you a rabbit named Mopsy. Mopsy has long hair.
You introduce Mopsy to your other rabbit, Flopsy, who has short hair. Later that year Flopsy and Mopsy
produce a litter of one long-haired and seven short-haired bunnies. If short hair is dominant over long
hair, what are the probable genotypes of Flopsy and Mopsy?
In humans, albinism is caused by a recessive allele. Given the following information, predict the genotypic
and phenotypic ratios of the crosses and state the percent likelihood of the first child being an albino.
a) Homozygous dominant X heterozygous
b) Heterozygous X heterozygous
c) Homozygous recessive X heterozygous
A hornless bull is crossed with three cows A, B, and C. Cow A is horned and produces calf A’ which is also
horned. Cow B is hornless and produces calf B’ which is horned. Cow C is horned and produces calf C’ which
is hornless. Given that hornlessness is dominant, predict the genotypes and phenotypes for each of the
seven animals.
Single Trait Crosses - Practice Questions
In pea plants, round peas are dominant over wrinkled. Predict the genotypes and phenotypes that will be
found if a plant homozygous for round peas (RR) and a plant homozygous for wrinkled peas (rr) are
crossed.
In tomatoes, red fruit (R) is dominant over yellow fruit (r). If a heterozygous red fruit is crossed with a
yellow fruit,
a) What is the appearance of the F1 generation?
b) What are the genotypes of the F2 generation if two plants from the F1 generation are crossed?
c) What are the phenotypes of the F2 generation?
In cattle, horns (h) are recessive to hornless (H). If two homozygous cattle, one hornless and the other
horned, are crossed, what are the genotypes and phenotypes of the first generation?
As a reward for being a good student, Mrs. Renkema gives you a rabbit named Mopsy. Mopsy has long hair.
You introduce Mopsy to your other rabbit, Flopsy, who has short hair. Later that year Flopsy and Mopsy
produce a litter of one long-haired and seven short-haired bunnies. If short hair is dominant over long
hair, what are the probable genotypes of Flopsy and Mopsy?
In humans, albinism is caused by a recessive allele. Given the following information, predict the genotypic
and phenotypic ratios of the crosses and state the percent likelihood of the first child being an albino.
a) Homozygous dominant X heterozygous
b) Heterozygous X heterozygous
c) Homozygous recessive X heterozygous
A hornless bull is crossed with three cows A, B, and C. Cow A is horned and produces calf A’ which is also
horned. Cow B is hornless and produces calf B’ which is horned. Cow C is horned and produces calf C’ which
is hornless. Given that hornlessness is dominant, predict the genotypes and phenotypes for each of the
seven animals.