Name: _______________________________________________ Date: ______________________ Period: ________
Biology: All Inheritance Patterns (Genetics Review WS)
Directions: Answer the following questions and complete the Punnett Squares and Pedigree Charts.
Autosomal Recessive Inheritance
1) Mendel noticed that when a tall (T) plant and a short (t) plant were crossed, all the offspring were tall in height.
Cross a heterozygous tall plant with a short plant. Complete the Punnett square below to support your answer.
a. What are the genotypes of each parent? _________________
b. Which trait is dominant? _____________________________
2) What is the probability of getting a:
c. Tall pea plant? ________________
d. Hybrid pea plant? _____________
e. Purebred plant? ______________
3) Find the following ratios:
a. Genotypic: __________________________________ b. Phenotypic: ___________________________________
4) Phenylketonuria (PKU) is a recessive condition where sufferers lack an enzyme to break down tyrosine in their diet.
This condition, if left untreated, causes brain damage and retardation. Both Rita and Dexter are carriers of this
disorder and do not suffer from any symptoms. Their son, however, has PKU. Complete the Punnett square and
pedigree chart for all mentioned in the story).
Draw your Punnett Square below
Draw your pedigree chart below
a. What are the phenotypes of each parent? ______________
5) What is the probability of getting:
b. Two healthy children? ______________________ c. A child who carries the disorder? __________________
d. A child who has PKU? ____________________ e. A Homozygous recessive child? ______________________
f. If their child is a carrier of PKU, does this mean the child has the disorder? Explain: _____________________
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Sex-Linked Inheritance
6) The gene for normal blood clotting (Xh) is dominant to the gene for Hemophilia (XH), which is a sex-linked recessive
disorder found on the X-chromosome of males and females. Marge is a healthy carrier of hemophilia and Homer is
completely healthy. What would be Bart, Liza, and Maggie’s genotypes? Complete the Punnett square and pedigree
chart for all mentioned in the story.
Draw your Punnett Square below
Draw your pedigree chart below
a. What is the genotype of Marge? ________ Homer? ________
7) What is the probability of getting a:
b. Daughter with hemophilia? ________________________ c. Carrier? ________________________________
d. Son with hemophilia? ____________________________ e. Healthy child? ___________________________
8) Can males be carriers of sex-linked traits? Explain:
__________________________________________________________________________________________
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9) Duchene Muscular Dystrophy (DMD) is a sex-linked recessive disorder found on the X chromosome. Sufferers with
DMD (Xd) lack the protein called dystrophin. Because sufferers lack this protein, their muscle cells wear away sooner
than those unaffected causing early death. Abby is homozygous recessive for DMD and Ray is healthy. They want to
know, if they have a son, what his genotype will be? Create a Punnett square & pedigree chart for all mentioned in
the story.
Draw your Punnett Square below
Draw your pedigree chart below
a. What is the genotype of Abby? _________ Ray? _________
10) What is the probability of getting a:
b. A child with DMD? _____________ c. Girl with DMD? ____________ d. Homozygous child?_____________
e. If this couple has a boy, what are the chances that the boy will have DMD? ___________________________
Autosomal Dominant Inheritance
11) Huntington’s disease (HD) is a dominant disorder where only 1 copy of a defected allele will cause the sufferer to
lose brain function and eventually die. Russ and Leslie met at a HD support clinic and both contain the HD allele.
However, they still want to plan a future together and what to know the chances of having a child without HD.
Can you help them? Create a Punnett square and pedigree chart for all mentioned in the story.
Draw your Punnett Square below
Draw your pedigree chart below
a. List the genotypes of each parent? ________________
12) What is the probability of getting a:
b. A healthy child? ______________________________
c. A heterozygous child? _______________________ d. A homozygous dominant child? __________________
Incomplete Dominance Inheritance
13) Define incomplete dominance:
________________________________________________________________________________________________
14) Circle the answer: Would you describe incomplete dominance or codominance as a blend of phenotypes?
15) Think about the flower color problems we previously did in class. How could one create all three colors at a time
(red, pink, white)? Support your answer with a Punnett Square.
a. What are the phenotypes of each parent? ________________________
16) What is the probability of getting:
b. White flowers? ___________________________________
c. Homozygous flowers? _____________________
d. Heterozygous flowers? _____________________________
Codominant Inheritance
17) Define codominance:
________________________________________________________________________________________________
________________________________________________________________________________________________
18) There are 3 alleles for blood (A, B, O). A and B are both dominant, and only O is recessive.
Keva has heterozygous type B blood and Kobe has type O blood. Complete the Punnett Square below.
a. What is Keva’s genotype? ____________ Kobe’s? ____________
19) What is the probability of getting:
b. The same genotype as Keva? ______________________
c. The same phenotype as Kobe? _____________________
d. A child with codominant blood? ____________________
e. A child with homozygous B blood? __________________
Additional Review Questions:
20) What is the point of a Punnett Square?
______________________________________________________________________________________________
21) What is the Law of Segregation? __________________________________________________________________
_____________________________________________________________________________________________
22) a. In terms of genetic material, what do you inherit from your mother? ___________________________________
b. Your father? ____________________________________________
23) List and explain one example of how environment and genotype can interact.
______________________________________________________________________________________________
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24) What is a polygenic trait? List an example:
______________________________________________________________________________________________
25) Describes what happens in epistasis.
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