This document contains genetics practice problems involving monohybrid and dihybrid crosses. It begins by asking the reader to identify genotypes as heterozygous or homozygous. It then asks the reader to determine possible phenotypes for several genotypes. It provides Punnett squares and asks the reader to determine genotypic and phenotypic ratios for given crosses involving traits such as seed shape, plant height, and eye color.

1. Ch 3 Section 2: Genetics Practice Problems
1. For each genotype below, indicate whether it is heterozygous
(He) or homozygous (Ho)
AA _____ Ee ____ Ii _____ Mm _____
Bb _____ ff ____ Jj _____ nn _____
Cc _____ Gg ____ kk _____ oo _____
DD _____ HH ____ LL _____ Pp _____
2. For each of the genotypes below determine what phenotypes
would be possible.
Purple flowers are dominant to Brown eyes are dominant to blue
white flowers. eyes
PP __________________ BB ________________
Pp __________________ Bb ________________
pp __________________ bb ________________
Round seeds are dominant to Bobtails in cats are recessive.
wrinkled seeds.
TT _________________
RR __________________
Tt _________________
Rr __________________
tt __________________
rr __________________
3. For each phenotype below, list the genotypes (remember to use
the letter of the dominant trait)
Straight hair is dominant to Pointed heads are dominant to round
curly. heads.
____ straight _____ pointed
____ straight _____ pointed
____ curly _____ round
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3. Punnett Square,
Genotypic Ratio (GR) (BB : Bb : bb)&
5.
GR:___________
6.
GR:___________
7.
Practice with Crosses. Show all work!
5. A TT (tall) plant is crossed with a tt
(short plant).
What percentage of the offspring will be
tall? ___________
6. A Tt plant is crossed with a Tt plant.
GR:___________
What percentage of the offspring will be
short? ______
8.
7. A heterozygous round seeded plant (Rr)
is crossed with a homozygous round seeded
plant (RR).
What percentage of the offspring will be 3
homozygous (RR)? __________

4. 16. Set up the Punnett squares for each of the crosses listed below. Round
seeds are dominant to wrinkled seeds. Show GR & PR.
What percentage of the offspring will be
round? _______________
Rr x rr
GR: ______________
What percentage of the offspring will be
round? _______________
RR x rr
GR: ______________
What percentage of the offspring will be
round? _______________
RR x Rr
GR: ______________
What percentage of the offspring will be
round? _______________
Rr x Rr
GR: ______________
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