Punnett Square Worksheet
Complete the following monohybrid crosses: draw a Punnett square, list the ratios of the
genotypes and phenotypes of the offspring.
Example: A green pea plant (GG) is being crossed with a green pea plant (Gg).
G
G
g
G
GG
GG
Gg
Gg
Genotype = 2 GG : 2 Gg : 0 gg
or = 2 GG : 2 Gg
Phenotype = 4 Green pea plants : 0 other color
1) A green pea plant (Gg) is crossed with a yellow pea plant (gg).
2) A tall plant (TT) is crossed with a tall plant (Tt).
3) A tall plant (Tt) is crossed with a short plant (tt).
4) A red flower (Rr) is crossed with a white flower (rr).
5) A white flower (rr) is crossed with a white flower (rr).
6) A black chicken (BB) is crossed with a black chicken (BB).
Complete the following problems. List the parent genotypes, draw and fill in a Punnett square,
and then list the ratios of offspring genotypes and phenotypes. Heterozygous means two
different alleles in the genotype. Homozygous means tow of the same allele in the genotype.
1. A homozygous dominant brown mouse is crossed with a heterozygous brown mouse (tan
is the recessive color).
2. Two heterozygous white (brown fur is recessive) rabbits are crossed.
3. Two heterozygous red flowers (white flowers are recessive) are crossed.
4. A homozygous tall plant is crossed with a heterozygous tall plant (short is the recessive
size).
5. A heterozygous white rabbit is crossed with a homozygous black rabbit.
Punnett Square Worksheet - Human Characteristics
Directions: Complete the following Punnett Squares. Be sure that you include the ratios of the
genotypes (and the words used to describe those alleles) and phenotypes of the offspring.
6. B= Brown eyes. b= blue eyes. Mom= Bb.
if they chose to have children?
Genotypes
Dad= BB. What are the eye color possibilities
Phenotypes
7. Curly hair is recessive, and straight hair is dominant. A woman with curly hair marries a man
who is homozygous dominant for straight hair. Predict the outcomes for their children.
Alleles
Genotypes
Phenotypes
8. Attached earlobes are dominant over free hanging earlobes. Complete the Punnett Square
for the following individuals: Mom=BB and Dad=bb
Alleles
Genotypes
Phenotypes
9. Freckles are recessive. No freckles are dominant. Mom= heterozygous. Dad=homozygous
recessive Possible outcomes for kids?
Alleles
Genotypes
Phenotypes
10. A dihybrid cross follows two traits. If the mother has brown eyes and curly hair (Bb Hh) and
the father has the same characteristics (Bb Hh). They both make gametes that are (BH) or (Bh) or
(bH) or (bh). Make a Punnett square for this dihybrid cross. The possible gametes are already
labeled. Some possible offspring genotypes are already done.
BH
BH
Bh
bH
bh
BB HH
BB Hh
Bb HH
Bb Hh
Bh
bH
bh
11. The possible genotypes of the offspring are listed in the table. Write the number of each
possible genotype in the Punnett Square. List the phenotypes of the offspring. List the numbers
of each phenotype.
Genotypes
BBHH
Amount
1
Phenotype
Brown eyes
Straight hair
BBHh
BBhh
BbHH
BbHh
Bbhh
bbHH
bbHh
bbhh
12. Use the numbers to write the ratio of the phenotypes.
Amount