Download Punnett Square Practice

SEX-LINKED, CODOMINANCE, AND INCOMPLETE DOMINANCE
PUNNETT SQUARE PRACTICE
1. Make a punnett square the shows the chance of two parents having a boy or a girl. What %
of the children will be boys?
2. Colorblindness is an X-linked Recessive genetic disorder. Make a punnet square showing
the cross between a heterozygous mother and a father who is colorblind.
a. What are the genotypes of the parents?
b. What are all the possible genotypes of the offspring?
c. What percentage of the female children are carriers of the disease?
d. What percentage of the children have the disease?
e. Who did the father get his copy of the gene from?
3. Duchenne muscular dystrophy is an X-linked Recessive disorder. Make a punnet square
showing the cross between a heterozygous mother and a father who DOES NOT have
DMD.
a. What percentage of the female children will carry the gene?
b. What percentage of the male children will be affecte by the disease?
c. Why are the females in the family NOT afflicted with DMD?
4. A – type blood and B – type blood are co-dominant. O –type blood is recessive trait. Make
a punnett square to show the possible blood types of a child. The mother is homozygous A
type blood and the dad who is type O blood. What is the phenotype ratio?
5. What are the possible blood types of a child from a parent with heterozygous type A blood
and a parent with type AB blood?
When alleles are incompletely dominant, neither allele is completely dominant nor
completely recessive. A heterozygous individual has an intermediate phenotype. In this lab,
you will explore incomplete dominance by examining the human trait of hair texture.
Use the information below to answer the questions that follow.
TABLE 1. FAMILY PHENOTYPES
Individual
Kathy's father
Kathy's mother
Kathy
Kathy's brother
Hair Texture
straight
curly
wavy
wavy
6. Conclude If IS is the allele for straight hair and IC is the allele for curly hair, then what are
the genotypes of each individual in Kathy's family?
7. Predict If Kathy married a man with straight hair and they had children, what type of hair
texture (straight, curly, wavy) might their children have? Explain your answer using Punnett
squares.
8. Predict If Kathy married a man with curly hair and they had children, what type of hair
texture might their children have? Explain your answer using Punnett squares.
9. Infer If Kathy married a man with wavy hair and they had children, what type of hair
texture might their children have? Explain your answer using Punnett squares.