Exam 2
Name:
Biology 355
Spring, 2017
Instructions:
You may use the backs of the pages for scratch paper.
For your final
answer, please use blue or black ink.
If you need to change your answer, draw a line
neatly through the old one and write in the new one.
Write your name at the top of this page.
You may use a calculator.
Please turn off your cell phone.
Do not use a cell phone,
notebook computer or other computing device during the exam.
Pascal’s Triangle:
1
1
1
1
2
1
1
3
3
1
1
4
6
4
1
1
5
10
10
5
1
etc.
A term in the binomial expansion:
n!/(s!t!)
*
a
s
b
t
where
s + t = n; a
and
b
are probabilities
such that
a + b = 1.
Prob(A and B) = Prob(A) x Prob(B)
if
A
and
B
are independent.
Prob(A or B) = Prob(A) + Prob(B)
.
(This is a special case that we use in class.)
χ
2
= Σ (oe)
2
/e
e
= expected,
o
= observed and the sum is over all possible outcomes.
df
= degrees of freedom =
n  1
where
n
is the number of outcomes.
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1.) (8 pts) Suppose a woman who is a carrier for Xlinked colorblindness marries a man
who has Xlinked colorblindness.
Part a: 6 pts, including
2 for correct notation.
2 pts for part b
X
+
is OK for wildtype.
a.) What are the expected genotypes and genotypic ratios of their sons?
Daughters?
(For full credit you must use the correct notation for Xlinked traits in humans.)
C
: normal allele
c
: colorblindness allele
P
X
C
X
c
x
X
c
Y
X
C
X
c
X
c
X
C
X
c
X
c
X
c
genotypes of daughters:
X
C
X
c
,
X
c
X
c
in a 1:1 ratio.
Y
X
C
Y
X
c
Y
genotypes of sons:
X
C
Y, X
c
Y
in a 1:1 ratio
b.) What are the expected phenotypic ratios of the sons and daughters?
Daughters:
1:1 normal vision to colorblind
Sons: 1:1 normal vision to colorblind
The phenotype of a carrier is normal.
2) (4 pts)
For a person with type AB blood (genotype
i
A
i
B
), both antiA antibodies and
antiB antibodies will clump the red blood cells.
This phenomenon is an example of
(circle one):
A.) Incomplete dominance
B.) Partial dominance
C.)
Codominance
D.) Gainoffunction
E.) Lossoffunction
3.) (10 pts) Schmoos can be either graceful (G) or gruesome (g).
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 Summer '14
 Biology, Genetics

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