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NAME:______
KEY _______
Page 1
(1)
[15 points
]
Scientists studying pond scum at ASU have found an organism
with four sexes.
Suppose the parents
are P1= AAAa, P2 =
AAaa, P3 = AAAA,
and P4 = Aaaa.
(a)
What is the probability of getting an AAAA offspring?
(3/4)*(1/2)*(1)*(1/4) = 3/32 =
0.09375
(b)
What is the probability
of getting an AAAa offspring?
a from P1:
(1/4)*(1/2)*(1)*(1/4) = 1/32 =
0.03125
a from P2:
(3/4)*(1/2)*(1)*(1/4) = 3/32 =
a from P3:
(3/4)*(1/2)*0*(1/4) =
0
a from P4:
(3/4)*(1/2)*(1)*(3/4) = 9/32 =
0.28125
total = 13/32 =
0.40625
(c)
Given that the offspring is AAAa, what is the chance that Parent four (P4)
contributed the a allele?
(9/32)/(13/32) = 9/13 = 0.6923
(2)
[10 points
]
Consider a cross of AABBCcDD x AaBbCcDd.
(a)
What is the probability of an ABCD offspring? (Loci unlinked)
1*1*(3/4)*1 = 3/4 = 0.
.75
(b)
Given your answer (a), what is the probablity that the first
five offspring are all ABCD?
(3/4)
5
=
0.2373
(c)
What is the probability that none of the first five offspring are
ABCD?
(1/4)
5
=
0.000977
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View Full DocumentNAME:______
KEY _______
Page 2
(3)
[15 points
]
Two autosomal loci determine the dreaded
sparky
phenotype:
the mustard locus (with alleles M = mustard, m = normal) and the rust locus
(alleles R = rust, r = normal).
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 Spring '09
 walsh

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