In rugrats, there are two fur colors, yellow and black, and black fur is dominant (use B for the black allele, and b for the yellow). Rugrats also have two tail lengths, short and long, with the long tails being dominant (use T for the long allele, and t for the short). The two genes are not linked. Use this information to answer questions 1 - 6.
1. A true-breeding rugrat
with black fur is mated to a true-breeding rugrat with yellow fur.
Two
of the resulting F1 offspring are then mated to produce the
F2.
a) What are the genotype(s)
and phenotype(s) of the F1 (the parents of the F2)?
b) What are all of
the possible genotypic and phenotypic ratios in the F2 generation?
2. A rugrat with black
fur is mated to one with yellow fur.
a) What are all of
the possible genotypes of the two parent rugrats?
b) What are all of
the possible genotypic and phenotypic ratios in their offspring?
c) The rugrats have
an offspring with yellow fur. What are the genotypes of the parents
and the offspring?
3. Two rugrats with black
fur are mated.
a) What are all of
the possible genotypes of the two parent rugrats?
b) What are all of
the possible genotypic and phenotypic ratios in their offspring?
c) The rugrats have
an offspring with yellow fur. What are the genotypes of the parents
and the offspring?
4. A true-breeding black
rugrat with a long tail is mated to a true-breeding yellow rugrat with
a short tail. Two of the resulting F1 offspring are then
mated to produce the F2.
a) What are the genotype(s)
and phenotype(s) of the F1 (the parents of the F2)?
b) What are all of
the possible genotypic and phenotypic ratios in the F2 generation?
5. A black, short-tailed
rugrat is mated to a yellow, short-tailed rugrat.
a) What are all of
the possible genotypes of the two parent rugrats?
b) What are all of
the possible genotypic and phenotypic ratios in their offspring?
c) The rugrats' first
offspring has yellow fur, and a short tail. What is its genotype?
d) What are the genotypes
of the parents?
6. A black, short-tailed
rugrat is mated to a yellow, long-tailed rugrat.
a) What are all of
the possible genotypes of the two parent rugrats?
b) What are all of
the possible genotypic and phenotypic ratios in their offspring?
c) The rugrats' first
offspring has black fur, and a long tail. What is its genotype?
7. The rugrat genes for
tail length and whisker color are linked. Long tail is dominant to
short tail (use T for the long allele, and t for the short), and blackwhiskers
are dominant to white whiskers (use B for the black allele, and b for the
white). A true-breeding rugrat with white whiskers and a long tail
is mated to a true-breeding rugrat with black whiskers and a short tail.
Two of the resulting F1 offspring are then mated to produce
the F2.
a) What are the genotype(s)
and phenotype(s) of the F1 (the parents of the F2)?
b) What are all of
the possible genotypic and phenotypic ratios in the F2 generation?
8. A short-eared rugrat
is mated to a long-eared rugrat, and all of their offspring are medium-eared.
a) What is the dominance
relationship between the two alleles (short and long)?
b) What are the genotypes
of the parents and the offspring?
9. Two medium-eared rugrats
are mated. Use the information from question 8.
a) What are all of
the possible genotypes of the two parent rugrats?
b) What are all of
the possible genotypic and phenotypic ratios in their offspring?
10. In rugrats, curly fur is
dominant to straight fur and sex-linked (use XF for the curly
allele, and Xf for the straight allele). A male with straight
fur is mated to a female with curly fur.
a) What are all of
the possible genotypes of the two parent rugrats?
b) What are all of
the possible genotypic and phenotypic ratios in their offspring?
c) The rugrats have
a male offspring with straight fur. What are the genotypes of the parents
and the offspring? (Also, from which parent did the offspring receive
each of his alleles?)
University of Minnesota's
General
Biology Home Page U
of MN web mail site
Established & maintained by Theresa Onstad
(Boettcher).
boet0027@tc.umn.edu