DO NOW
• Pick up a Sponge Bob punnett square practice
• Put your name on it
• DO NOT START IT YET
Punnett Square
Vocab
• Homozygous/Purebred – RR, rr, gg, TT
• Heterozygous/Hybrid – Rr, Tt, Gg
• Dominant – Capital Letter
• Recessive – lowercase
• Genotype – Letter combos (GG, Gg, Tt)
• Phenotype – Physical Characteristics
Your Job
• Complete the punnett square practice
• Complete your traits lab and hand it in
DO NOW
• Take out your Sponge bob practice and look
over the keys
• Circle any questions you have
Do Now – Class 3
• Open to a blank sheet of paper in your
notebook
• Label it
– Punnett Square Practice
Punnett Square
Practice Problems
Vocab
• Homozygous/Purebred – RR, rr, gg, TT
• Heterozygous/Hybrid – Rr, Tt, Gg
• Dominant – Capital Letter
• Recessive – lowercase
• Genotype – Letter combos (GG, Gg, Tt)
• Phenotype – Physical Characteristics
Problem 1
• Create a punnett square to determine percent
probabilities of genotypes and phenotypes of
the offspring of a pea plant with yellow pods
crossed with a plant that is heterozygous for
pod color. (Green pod (G) color is dominant.)
G
g
g
g
Gg
Gg
gg
gg
Genotype ratios
Gg 50%
gg 50%
Phenotype ratios
Green pods 50%
Yellow pods 50%
Problem 2
• Create a punnett square to determine percent
probabilities of genotypes and phenotypes of
the offspring of two pea plants that are both
heterozygous for seed shape. (Round shape(R)
is dominant over wrinkled.)
R
r
R
r
RR
Rr
Rr
rr
Genotype ratios
RR 25%
Rr
50%
rr
25%
Phenotype ratios
Round seeds 75%
Wrinkled seeds 25%
Problem 3
• Create a punnett square to determine percent
probabilities of genotypes and phenotypes of
the offspring of two pea plants that both are
homozygous for yellow seed color. (Yellow
color (Y) is dominant over green.)
Y
Y
Y
Y
YY
YY
YY
YY
Genotype ratios
YY
Phenotype ratios
Yellow seeds 100%
100%
Problem 4
• Create a punnett square to determine percent
probabilities of genotypes and phenotypes of
the offspring of a pea plant that is
homozygous for yellow seed color with a plant
with green seeds. (Yellow (Y) color is dominant
over green.)
y
y
Y
Y
Yy
Yy
Yy
Yy
Genotype ratios
Yy 100%
Phenotype ratios
Yellow seeds 100%
Problem 5
• Create a punnett square to determine percent
probabilities of genotypes and phenotypes of
the offspring of a pea plant that is
homozygous for green pod color with a plant
that is heterozygous for pod color. (Green pod
color is dominant (G) over yellow.)
G
g
G
G
GG
GG
Gg
Gg
Genotype ratios
GG
50%
Gg
50%
Phenotype ratios
Green pods 100%