SURNAME / INITIALS ____________________ (Please Print)
FIRST MIDTERM TEST
Feb 5, 2011 - 9am -12 noon
25% of Final Mark
This test paper is composed of 40 equally weighted questions covering 17 sides (excl. cover).
The last page contains a table of critical chi-square values. Please ensure that the exam is
Although there are no deliberate tricks on this paper there is ample opportunity to make
careless oversights; READ THE QUESTIONS CAREFULLY.
Answers will be subject to computerized matching analysis to detect
Since it is impossible to provide equal access to instructors during the Test, proctors will
NOT answer questions of interpretation.
All answers must be recorded on the Scantron sheets within the 3 hour time limit.
1. Fill in your NAME at the top of the scantron sheet and the exam paper
2. STUDENT NUMBER - Print the digits of your student number in the squares provided.
Mark the corresponding bubble in the column below each printed digit.
3. SECTION AND ANSWER SHEET - Leave these areas blank.
4. In the EXAM CODE section enter 444 5. Mark one choice from the alternatives provided for each question.
6. Submit your test paper and the Scantron sheet SEPARATELY.
1. A Neurospora ala2 mutant haploid (requires alanine for growth) is crossed with a leu5 mutant
haploid (requires leucine for growth). The diploid produces ordered asci. 100 ordered asci are
analyzed and assigned to one of the following seven possible types. The number of each
possible type is given on the bottom row of the table.
Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Type 7
ala2 + ala2 leu5 ala2 + ala2 + ala2 + ala2 leu5 ala2 leu5
ala2 + ala2 leu5 + + ala2 leu5 + leu5 + + + +
+ leu5 + + + leu5 + leu5 + leu5 + + + leu5
+ leu5 + + ala2 leu5 + + ala2 + ala2 leu5 ala2 +
80 0 0 10 10 0 0
The genes ala2 and leu5 are
B. 50 map units (mu) apart.
C. 10 mu apart.
D. 5 mu apart.
E. 1 mu apart.
2. Using the tetrads dissected in above question 1. Which of the following for leu5, ala2 and a
centromere (cen) best describes what is observed?
A. cen between leu5 and ala2.
B. ala2 between cen and leu5.
C. leu5 between cen and ala2.
D. ala2 and leu5 linked but neither is linked to cen.
E. ala2, leu5 and cen are unlinked.
2 3. You mate arg2 leu3 trp4 haploid yeast with wild-type haploid yeast. You induce meiosis in
the resulting diploid and dissect the tetrads. Looking at each locus in pairs you get the following
numbers for 100 dissected tetrads.
leu3 arg2 leu3 + leu3 arg2
leu3 arg2 leu3 + leu3 +
+ + + arg2 + arg2
+ + + arg2 + +
43 3 54
leu3 trp4 leu3 + leu3 trp4
leu3 trp4 leu3 + leu3 +
+ + + trp4 + trp4
+ + + trp4 + +
18 17 65
arg2 trp4 arg2 + arg2 trp4
arg2 trp4 arg2 + arg2 +
+ + + trp4 + trp4
+ + + trp4 + +
54 2 44
You conclude that
A. all genes are linked.
B. only arg2 and trp4 are linked.
C. only leu3 and trp4 are linked.
D. only arg2 and leu3 are linked.
E. all genes are unlinked.
3 4. If recombination occurred before DNA replication would you be able to map a centromere
linked gene in an ordered tetrad? For example, leu6 is a centromere linked gene and below is a
diagram of the two unreplicated homologous chromosomes.
___X___ because ____Y_____.
A. Yes second-division segregation will be observed
B. No no second-division segregation will be observed
C. Yes only first division segregation will be observed
D. No only second division segregation will be observed
E. Yes no first division segregation will be observed