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Biology 202
Problem Set 1
1/21/11
This problem set covers material from January 10
th
through January 24
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From Griffiths et al.:
Chapter 1, problems 5, 6, 8, 9, 17, 19
Chapter 2, problems 2, 3, 9, 11, 13
Chapter 3, problems 7, 15, 16, 18, 20, 35, 36
Chapter 7, problems 1, 2, 3, 5, 18, 19, 24, 26, 27
Hand in answers to the following questions, due at 4:00 pm on January 28
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1. You’re working in a lab that studies a particularly fetching bird from Brazil.
This bird has a
diploid number of 20 chromosomes in its somatic cells, consisting of 10 homologous pairs
(i.e. 10 maternal and 10 paternal chromosomes).
Another student in your lab tells you that
only onefourth of the gametes produced by meiosis in this bird will have all of it’s
chromosomes from either maternal or paternal origin (i.e. all the chromosomes from dad or all
the chromosomes from mom).
Assume that meiosis in this bird works just like meiosis in
organisms we’ve talked about in class and explain whether you think your lab buddy is
correct.
The probability that the first chromosome is derived from either the mother or the
father is 1 (it has to come from one or the other). The probability that the second
chromosome comes from the same parent as the first is ½, the probability that the third
chromosome comes from the same parent as the first is also ½ and so on for all the
chromosomes. Therefore, the probability that the ten chromosomes in a gamete come
from one parent is (1)(½)(½)(½)(½)(½)(½)(½)(½)(½) = 1/512. Therefore, the lab buddy is
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 Spring '11
 Smith
 Biology

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