Genetics Review
1.
What is the Law of Dominance and give an example of a punnett square illustrating this law?
2. What are the phenotype ratio and the genotype ratio for the Law of Dominance?
3. When forming gametes, two alleles responsible for a trait separate from each other and are recombined at
fertilization. This is called __________________________________
4. What are the phenotype ratio and the genotype ratio for the Law of Segregation? Draw a punnett square
illustration this law.
5. Differentiate between incomplete dominance and codominance and give an example of each.
6. Who is the “Father of Genetics”?
7. If you cross a homozygous dominant with a homozygous dominant, you will get ____________ ____________
Genetics Problems:
A. Monohybrid Crosses—Autosomal Single-Gene Traits:
Given: Black fur (B)is dominant over white (b) fur in rabbits.
8. Cross a homozygous black rabbit with a homozygous white rabbit.
a. What are the genotypes of the mom and dad rabbits? _____ x _____
Show your work with a Punnett square to the right 
b. What are the genotypes of the offspring? _____________
c. What’s the ratio or percentage of each?____________
d. What are the phenotypes of the offspring? _____________
e. What’s the ratio or percentage of each? ____________
9. Cross a heterozygous black rabbit with a heterozygous black rabbit.
a. What are the genotypes of the mom and dad rabbits? _____ x _____
Show your work with a Punnett square to the right 
b. What are the genotypes of the offspring? _____________
c. What’s the ratio or percentage of each?____________
d. What are the phenotypes of the offspring? _____________
e. What’s the ratio or percentage of each? ____________
B. Monohybrid Crosses—Autosomal Intermediate Inheritance: Incomplete Dominance
Sponge Bob and his pal Patrick love to go jellyfishing at Jellyfish Fields! The fields are home to a special type of
green jellyfish known as Goobers and only really great jellyfishermen are lucky enough to catch some on every
trip. Many of the jellyfish are yellow (YY) or blue (BB), but some end up green as a result of incomplete
dominance. Use this information to help you complete each section below.
10. What would happen if SpongeBob and Patrick crossed two “goobers” or green jellyfish? Complete a
Punnett square to the right to help you determine the probability for each color of jellyfish.
(a) Give the possible genotypes and phenotypes for the offspring.
(b) What percentage of the offspring would be yellow? _____%
(c) What percentage would be blue? _____ %
(d) What percentage would be “goobers” (green)? _____ %
11. What would happen if they crossed a yellow jellyfish with a goober? Complete a Punnett square to help
you determine the probability for each color of jellyfish.
(a) Give the possible genotypes and phenotypes for the offspring.
(b) What percentage of the offspring would be yellow? _____%
(c) What percentage would be blue? _____ %
(d) What percentage would be “goobers” (green)? _____ %
C. Monohybrid Crosses—Autosomal Intermediate Inheritance: Multiple Alleles & Codominance
12. Give the genotypes for type A= ____ (Heterozygous) or _____ (homozygous). Type B = ____ (hetero) or
_____ (homo); AB = _____; type O = _____.
13. List the possible blood types of offspring if Mom is heterozygous for type A and Dad is homozygous for
type B.
14. If a person has type AB blood and marries a person who also has type AB blood, could they have a child
with type O blood? Prove with a punnett square
D. Dihybrid Cross.
15. Cross a heterozygous tall,blue flower with a heterozygous tall, blue flower.
The letter for blue is B. The letter for white is b. The letter for tall is T. The letter for short is
t.
a. The genotypes of the parent flowers are _______ x ________
Show your work in a Punnett square: (on next page)
d. What are the phenotypes of the offspring?
_____________
e. What’s the ratio or percentage of each?
______________
Fish traits
S- Shiney scales
s- dull scales
B- black spot on fin
b- no black spot on fin
SSBb (male) x Ssbb (female)
16. What trait will most likely be observed in all offspring of the above set
of parents? _________________________
In the space provided, write the letter of the description that best matches the term or phrase.
_____17.
_____18.
_____19.
_____20.
_____21.
_____22.
_____23.
_____24.
_____25.
_____26.
_____27.
_____28.
_____29.
_____30.
_____31.
_____32.
pedigree
incomplete dominance
sex-linked trait
P1 generation
F1 generation
F2 generation
alleles
dominant
recessive
homozygous
heterozygous
genotype
phenotype
law of segregation
law of independent assortment
codominance
A. the alleles of a particular gene are
different; Tt, Bb, Dd
B. the two alleles for a trait separate when
gametes are formed
C. the alleles of different genes separate
independently of one another during
gamete formation
D. both alleles contribute to the phonotype;
black / white chicken feathers
E. a graphic representation of a family tree
that shows patterns of inheritance
F. not expressed when the dominant form of
the trait is present
G. first two individuals crossed in a breeding
experiment and the first row of symbols on
a pedigree
H. physical appearance of a trait
I. white and red flowers cross and make pink
flowers
J. offspring of the F1 generation and the third
row of symbols on a pedigree
K. when the two alleles of a particular gene
are the same; HH, tt, BB, aa
L. different versions of a gene
M. offspring of the P generation and the
second row of symbols on a pedigree
N. only males are affected by a certain
disorder and females are carriers; trait
whose allele is located on the X
chromosome
O. genetic make-up of an organism
P. the expressed form of a trait
Know how to recognize alleles for monohybrids and dihybrids.
Be able to distinguish between genotype and phenotype; homozygous and heterozygous; purebred and hybrid
33. Huntington disease, a disease of the nervous system, is caused by an autosomal dominant gene. The
pedigree chart below illustrates a family with individuals who have Huntington disease. Use the chart to answer
the questions that follow. HINT: Write the genotypes for each individual in the pedigree before you start
answering the questions.
A
B
hh
Hh
C
D
E
F
hh
G
H
I
hh
J
K
Hh
L
Hh
M
N
O
HH
Key:
H
Female
Male
Huntington Disease
h
Normal Gene
Determining Genotypes from a Pedigree
34.Nearsightedness – or myopia – is a recessive trait. The shaded regions show individuals who are homozygous
recessive for myopia. They exhibit the trait being studied.
Label the generations P, F1, F2, and F3. Label the individuals in each generation A., B., etc. Start over
with A with each generation. Use the symbols E and e to label each of the individuals in the pedigree below.
35.Free ear lobes is a dominant trait. Attached ear lobes is a recessive trait. The shaded regions show
individuals who are homozygous recessive for attached ear lobes. They exhibit the trait being studied. They have
attached ear lobes.
Label the generations P, F1, F2, and F3. Label the individuals in each generation A., B., etc. Start over
with A with each generation. Use the symbols E and e to label each of the individuals in the pedigree below.