1. Genetics Practice Problems
1. Identify the following alleles as
dominant (D) or recessive (R).
B ___ i ___ Q ___ t ____
2. For each genotype below, indicate
whether it is heterozygous (He) or
homozygous (Ho), then (HoD) & (Hor)
Rr ______ HH ______
ii ______ Ww ______ D R D R He
Ho D
Ho r He

2. Genotype or Phenotype? PP Red hair Yellow Rr Tt Seeds ss Yy Short
Set of alleles P G 3. G P G P G G P G

3. what phenotypes would be possible.
4. For each of the genotypes below determine
what phenotypes would be possible.
Curly hair is dominant to straight hair.
Cc _________ CC ________
cc _________
5. Round seeds are dominant to square seeds.
RR _____________
Rr ______________
rr ______________
curly
curly
straight
round
round
square

4. (remember to use the letter of the dominant trait!).
6. For each phenotype below, list the genotypes
(remember to use the letter of the dominant
trait!).
Green eyes are dominant to blue eyes.
green eyes _____ blue eyes _____
green eyes _____ GG gg Gg

5. Brown hair is dominant to red hair. Bb x bb
7. Set up the Punnett square for each of the
crosses listed below:
Brown hair is dominant to red hair.
Bb x bb
What percentage of the the offspring will have
brown hair? B b b Bb bb
50% b Bb bb

6. Cross a heterozygous brown hair male with
8. Brown hair is dominant to red hair.
Cross a heterozygous brown hair male with
a heterozygous brown hair female.
What percentage of the the offspring will have
brown hair? B b B BB Bb
75% Bb bb b

7. Cross a heterozygous brown hair male with
9. Brown hair is dominant to red hair.
Cross a heterozygous brown hair male with
a heterozygous brown hair female.
What are the genotypic
and phenotypic ratios?
Genotypic Ratios:
Phenotypic Ratios: B b B BB Bb
1 BB: 2 Bb: 1 bb Bb bb b
3 brown hair: 1 red hair

8. Cross a homozygous brown hair with a red hair.
10. Brown hair is dominant to red hair.
Cross a homozygous brown hair with a red
hair.
What percentage of
the offspring will have
brown hair? B B b Bb Bb
100% b Bb Bb

9. Cross a homozygous brown hair with a red hair.
11. Brown hair is dominant to red hair.
Cross a homozygous brown hair with a red
hair.
What percentage of
the offspring will have
brown hair?
Genotypic Ratios:
Phenotypic Ratios: B B b Bb Bb b Bb Bb
4Bb
4 brown hair