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Name: _______________________________________
Period: ______ Date: _________
Punnett Squares Worksheet #4
1. Gender is determined by the combination of sex chromosomes inherited by a
person’s parents. As you’ll recall, women have two copies of the X chromosome,
while men have an X and a Y chromosome. Set up a Punnett square showing the
possible offspring of a man and woman.
How many offspring will be female? ________ %
How many offspring will be male?
________ %
2. Colorblindness is a sex-linked trait. The recessive trait for colorblindness is
located on the X chromosome.
a. Cross1 a carrier female with a normal male.
How many of the children are:
Colorblind Males? ________ %
Colorblind Females? ________ %
Normal (non-carrier) Males? ________ %
Normal (non-carrier) Females? ________ %
Carrier Males? ________ %
Carrier Females? ________ %
What is the chance of this couple having a colorblind son? ________________
What is the chance of this couple having a child with normal vision? _______________
1
Apparently you’re a matchmaker who dabbles in armchair genetics as a hobby? Weirdo.
b. A normal (non-carrier) female marries a colorblind male.
How many children are colorblind? _________ %
How many children are normal (non-carrier)? _______ %
How many children are carriers? _________ %
3. Hemophilia is a sex-linked trait that prevents blood from clotting at wounds. The
recessive trait for hemophilia is located on the X chromosome.
a. Show the results of a cross between a hemophilic male and a carrier female.
How many hemophilic children are:
Male? ________
Female? ________
How many normal (non-carrier) children are:
Male? ________
Female? ________
How many carrier children are:
Male? ________
Female? ________
b. A hemophilic son has a father and a mother without hemophilia. The
mother’s genotype is
a. XhY
b. XHXH
c. XhXh
d. XHXh
c. Ophelia is a girl with no hemophilia who has a brother (Phil) with
hemophilia. Her mother (Phyllis) has hemophilia. If Ophelia marries a
normal male, the chances of their having a hemophilic daughter are
a. 0
b. 1/4
c. 1/2
d. 3/4
4. The stupid Simpson gene is located on the Y chromosome. If a stupid Homer is
crossed with a normal Marge, what is the chance of their son being stupid?
Daughter?
Son: _____________
Daughter: ________________