REVIEW WORKSHEET

REVIEW WORKSHEET
Name ___________________________
Post Mendelian Genetics
Date _____________ Period ________
1. Hemophilia is a sex-linked recessive trait. A hemophiliac man marries a normal woman and their first son has
hemophilia. Did he get this trait from his dad or his mom? EXPLAIN using genotypes.
Mom- males get the “y” from their dad so the “X” is always from the mom.
What are the chances that their future sons and daughters will get the disease? Show the Punnett Square and give the
phenotypic ratios for this cross.
H
h
H h
h
h
H h
h h
X X (x) X Y
Phenotypic Ratio: 1:1:1:1
X
X
X X X XX
Y XHY XhY
2. If a man with blood type A, whose father had O type blood, marries a woman with AB, what is the expected
percentage of their children with B type blood? SHOW WORK.
Ao (x) AB
25% chance of a child with B blood
Pheno- 2: 1: 1:0
A
A AA
B AB
O
Ao
Bo
3. A man has normal color vision and his wife is colorblind. Their son and their daughter are both
colorblind(a sex-linked recessive trait). Which child is adopted? Prove your answer using genotypes.
b b
B
b
b
X X (x) X Y
The daughter was adopted. These two parents
never produce a colorblind daughter.
X
X
XB XBXb XBXb
Y XbY XbY
4. If a trait is sex-linked and recessive, will it show up more often in males or females? EXPLAIN!
Males because need only have one X to show a recessive trait
while females need 2 Xs.
5. List 5 reasons why Morgan chose Drosophila to be his organism for genetics research.
Easy to care for, short life span, large # offspring,
trait easy to identify, can control reproduction
6. Explain what causes different blood types in humans.
Blood types are determined by the types of antigens (A, B, or RH) that are
present/absent.
7. If a man with blood type A+ (whose father had blood types B-) marries a woman with type AB- blood.
Show the Punnett Square and phenotypic ratio for this cross.
AoRr (x) ABrr
2
AR
AARr
ABRr
Ar
Br
1 1
0
2
1 1
Ar
oR
or
AArr AoRr Aorr
ABrr BoRr Borr
0
Pheno ____ : ____ : ____ : ____ : ____ : ____ : ____ : ____
A+
B+ AB+
O+
ABAB- O-
8. A man is searching for his father who disappeared when he was a young boy. He thinks that blood typing may aid his
search. He is blood type O-(oorr). and he knows that his mother was blood type B+(BoRr). What blood types are
possible for his father? What blood types are not possible for his father? Make sure you give blood types NOT
genotypes.
Possible Blood Types: A+
A- B+ B- O+ O-
Not Possible Blood Types= AB+
9. Answer the previous question again but for a man who is AB- (ABrr).
Possible Blood Types: B+
B- AB+ AB-
AB-
(whose mother was A- (A?rr).
Not Possible Blood Types= A+
).
A- O+ O-
10. List the possible blood types that can be received by a person with blood type:
A+
A+ A- O+ O-
B-
B- O-
0+
O+ O-
AB- A-
B- AB- O-
11. Explain why a person with type O blood can’t receive B blood in a transfusion. Be as specific as possible.
Type O blood lacks antigens, so it will produce antibodies A&B that will attack any
foreign cell that contains A or B or both.
12. Colorblindness is a sex-linked recessive trait. Eye color is not sex-linked. (genes for eye color occur on autosomes.)
For simplicity, assume that eye color is due to one pair of alleles only, B (brown), and b (blue). A woman who has normal
vision and blue eyes marries a man who is colorblind and brown-eyed. Their first child is a boy with colorblindness and
blue eyes. Their second child is a girl with normal vision and brown eyes. Determine the genotypes of all family
members.
Woman=
XBXbbb
Man =
XbYBb
boy =
XbYbb
girl=
XBXbBb
13. In cats short hair (H) is dominant over long hair (h) and is carried on the autosomes, not sex-linked. Another gene, (B)
which is sex linked, produces yellow coat color; its allele (b) produces black coat color; and the heterozygous
combination produces tortoise shell coat color. If a long haired black male is mated with a yellow female homozygous
for short hair, what kind of kittens will be produced in the F1? Show the Punnett square, list all possible phenotypes.
hhXbY (x) HHXBXB
H- short hair
h- long hair
XB Yellow
XBXb tort
Xb black
hXb
hY
B b
B
HXB HhX X HhX Y
hX
b
Short, tortoise female & Short, Yellow Male
hY
B
B has a son
16. A normal couple
colorblindness
and muscular dystrophy (both sex-linked recessive traits). If the next
HhXBXBwithHhX
Y
child
is
a
boy,
what
is
the
probability
that
he
has
both
traits? What about the girls? Explain why the results for boys are
B
X
Yellow
different than those of the girls.
B b
Xgirls.
X tort
Probability next boy will have
BD
bd
BD bd
BD
Xb black
HX
Parents: X X (x) X Y
Son:
XbdY
XBD
Y
X
X
XBDXBD XBDXbd
XBDY XbdY
both traits 50% chance
Girls 0 % chance
Boys need only one recessive
allele for the trait to show up,
while females need two recessive
alleles.
17. Determine the genotypes of the following individuals, and then state which child was adopted (and give an
explanation as well). You DO NOT need to show a Punnett Square!
Mother = blood type A+ ( whose dad was B+ BoRr)
AoRr
B_rr)
ABRr
Father = blood type AB+ (whose mom was BDaughter = blood type B-
Borr
Son #1 = blood type O+
ooR?
Son #2 = blood type A-
A?rr
Son #1 The type A parent can pass down an “o” but that AB parent can
only pass down and “A or B”. So these two parents can never produce a
child that has the genotype “oo”
Review/Define the following:
Sex-Linked Traits -
Autosome –
Trait on the X-sex chromosome
Trait on a non-sex chromosome
Trait controlled by more than two alleles (such as blood type
which is controlled by either A, B, or O)
Multiple Alleles –
Traits for which there are two forms of the dominant allele
(such as AB in blood type)
Codominance-
Another type of antigen found on red blood cells. If present, than
the blood type is +. If not present, than the blood type is -.
Rh factor –
Genes on autosomes that are expressed differently in
males and females due to hormones
Sex Influenced traits –
Polygenic inheritance –
single trait.
When several genes contribute to the production of a