BIO 3070 – Genetics
Midterm #2
3/12/09
Name: ________________________________ TA’s name: __________________________
INSTRUCTIONS: Read before you start answering.
WRITE YOUR NAME AND ID NUMBER NEATLY ON EVERY PAGE OF THIS EXAM.
This is essential because the exams will be unstapled prior to grading. If your name is not on each page you may not receive credit for your answers.
This is a closed book exam. Cell phones and all other electronic communication devices must be turned off. There are 14 questions on this exam numbered 1 through 14. There are a total of
150 points possible. There are 10 pages on this exam, 8 of which have questions (this cover page has no questions, and 1 is a continuation page for a problem on the previous page). Check to make sure you have all 10 pages. Do not exceed the space provided and do not write your answers on the back of these pages. However, the backs of the pages may be used to perform calculations or to draft your answers but under no conditions will that written information be used to assign points.
Read the questions carefully and understand what is asked of you. Organize your thoughts and your work, so that the graders can clearly see what you are doing. If you come to a question and you don’t know how to answer it immediately, don’t panic. Skip the question and go on.
When you are done with the rest of the test, come back to it. You can get partial credit.
When solving problems it is not enough that you give the answer - you have to show how you arrived at that answer. You will not get credit unless you showed how you arrived at the answer. PLEASE WRITE YOUR NAME AND YOUR TA’S
NAME ON EVERY PAGE OF THE EXAM!!
Formula you may need to use:
RF = 0.5 X (number of second division asci) / (total gametes)
RF = 0.5 X (TT + (6 X NPD))/total gametes

Yellow page 1 of 10

Name __________________________________ TA’s name ____________________________
The first 7 questions are fill-in-the-blank. Each of the 11 blanks is worth two points. There are 22 points total for these 7 questions.
1.

Chromosomal mutations can be subdivided into two general categories: Mutational events that change the genic or genomic content, which are called _____ numerical__________ chromosome aberrations, and mutational events that change the genic or genomic arrangement ___________structural_______________ chromosome aberrations.

2.

Genetic counseling is often recommended for women who become pregnant late in their reproductive years. Diagnostic testing –___________amniocentesis___________ or
___________chorionic villus sampling___________ may then be recommended.

3.

A condition in which the chromosome number is not an exact multiple of the haploid number is termed ___________aneuploidy___________.

4.

The ___________primary sex ratio___________ reflects the proportion of males to females conceived in a population. The ___________secondary sex ratio___________ reflects the proportion of each sex that is born.

5.

A ___________replicon___________ is the length of DNA that is replicated following one initiation event at a single origin.

6.

___________Ordered tetrad______________ analysis can be used to determine the map distance between a gene and the centromere. This process is sometimes called
___________mapping the centromere___________.

7.

Nucleotides are linked by a ___________phosphodiester bond___________ between the phosphate group at the C-5' position and the OH group on the C-3' position.

Yellow page 2 of 10

Name: ___________________________________ TA’s name ____________________________
8.

(15 points)
a. (12 of the 15 points) Explain the origin of twin spots in Drosophila melanogaster. Draw diagram(s) to illustrate the mechanism by which twin spots arise.
The mechanism is somatic cell crossing over between two heterozygous loci as shown below in this figure taken from the book.

b. (3 of the 15 points) What is