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Punnetts 2 - Answers
a. 50%
1.
b. Women need 2 faulty X
genes to be colorblind, and
men only need the 1 faulty X
MOM
XC
XC
DAD
Y
XCXC
XCY
XC
XCXC
XCY
2.
a. XHXh, XhXh
b. If your father, mother, son,
or daughter has the disorder
MOM
XH
Xh
DAD
Y
XHXh
XHY
Xh
XhXh
XhY
3.
a. FF, Ff
b. Both parents were heterozygous;
they each had a recessive gene
MOM
F
F
DAD
f
FF
Ff
f
Ff
ff
#2 on Pg. 203
• Because males have only one X
chromosome, they show all the traitsgenes on that X. Females have two X’s,
so they have two chances to get a gene
that is good, and can show the good
trait.
Example: If females, have one gene on an X for
colorblindness, and one gene on the other X
for normal vision, she will have normal vision.
• incomplete dominance – when neither gene is
dominant, you have a blend
(Ex: red gene + white gene = pink flower)
• codominance – when both genes show up as a
trait
(Ex: red gene + white gene = red and white spots)
(Ex: type A gene + type B gene = type AB blood)
• polygenic – when more than 1 pair of genes
controls a trait
(Ex: skin color, eye color, hair color)