1) Hair color (red vs white) and length (short vs long) in trolls depends on two
unlinked loci, both of which exhibit complete dominance. Trolls homozygous
recessive for hair color have white hair and short hair traits is conferred by the
dominant allele for hair length.
A. You cross two individuals heterozygous at both loci, describe the genotypic
and phenotypic ratios of the offspring.
B. You find a Troll with red short hair but do not know its genotype. You
perform a test cross. The offspring of the test cross all have red hair and
half have short hair and half have long hair, what was the genotype of the
dragon you found?
2. You cross two individuals heterozygous at three loci that all show complete
dominance. The A locus determines length (A=long, a=short), the B locus
determines color (B=black, b = white) and the C locus determines shape (C=round,
c = square). Use the forked line method to write out the proportion of the offspring
from the cross that have each phenotype.
3. Predict the mode of inheritance (A. whether dominant or recessive, and B.
whether sex-linked or autosomal) for the following pedigree - which is for a kidney
disease in humans (filled in symbols, males represented by squares, females
represented by circles). Explain each of your answers by referring to individuals in
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Hair color: red hair is dominant to white hair
RR= red hair
Rr = red hair
Rr = white hair
Hair length: Short hair is dominant to long hair
SS = short hair
Ss = short hair
ss = long hair
Genotype of and individual heterozygous at both loci: RrSs
Phenotype of this individual: red hair, short hair
Genotypic and phenotypic ratio of a RrSs x RrSs cross
Possible genotypes: RRSS, RrSS...