Practice Quiz for General Genetics
Chapter 7 -- Linkage, Recombination, and Eukaryotic Gene Mapping
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1. A heterozygous fly with a wildtype phenotype is testcrossed and the following progeny are produced; groucho- 518; rough- 471; groucho, rough- 6; wildtype- 5. Which flies represent nonrecombinants?
A. groucho
B. wildtype
C. rough
D. groucho, rough
E. c & d
F. a & b
G. a & c

2. A lod score is a
A. measure of the interference of one crossover with another
B. measure of genetic diversity in a population
C. measure of the probability of linkage between two loci
D. measure of the number of human chromosomes in an hybrid cell

3. A coefficient of coincidence is
A. measure of the interference of one crossover with another
B. measure of the probability of linkage between two loci
C. measure of the number of human chromosomes in an hybrid cell
D. measure of genetic diversity in a population

4. A heterozygous trihybrid corn plant is testcrossed and the following progeny are produced (all traits are recessive to their wildtype alternative);
          booster                              6
          booster, silkless                  137       
          booster, liguleless, silkless      291
          liguleless                         142
          liguleless, silkless                 3
          silkless                            30
          booster, liguleless                 34
          wildtype                           339
What is the order of the loci on the chromosome?
A. liguleless, booster, silkless
B. booster, silkless, liguleless
C. silkless, liguleless, booster
D. liguleless, silkless, booster

5. Given the data for question 4, what is the map distance between liguleless and silkless
A. 33.5 m.u.
B. 36.8 m.u.
C. 7.4 m.u.
D. 35.3 m.u.

6. Two percentage of recombination equals a distance between the loci of
A. 200 map units
B. 2 centimorgans
C. 200 centimorgans
D. 20 map units

7.            cv     9 m.u.        st        18 m.u.           lx
            ------------------------------------------------------
If we have a chromosome with three loci in which the distance between the loci is as indicated, then the probability of a double cross-over is
A. 0.900
B. 0.016
C. 0.180
D. 0.081

8. The occurrence of tetratype tetrads in the ascomycete fungi could only occur if crossing over occurred during
A. the four strand stage
B. during G1 phase
C. the two strand stage
D. during S phase

9. The following mouse-human hybrid cell lines have the human chromosomes as shown in the first table and the human enzymes as shown in the second table.
                             human chromosome   
        clone         3   7   9   11  15  18  20
          X           -   -   -   +    +   +   +
          Y           +   +   -   +    -   +   -
          Z           -   +   +   -    -   +   +

                                                 clone                     
                                           X       Y       Z
          glutathione reductase            +       +       -
          malate dehydrogenase             +       -       -
          galactokinase                    -       +       +
Which chromosome is the carrier of galactokinase?
A. 3
B. 18
C. 7
D. 11

10. Which of the following is not true about crossing over?
A. it involves a physical exchange of genetic material between non-sister chromatids
B. it occurs before DNA synthesis
C. it leads to a recombination of genetic traits
D. it occasionally regenerates the extreme phenotype

Last updated on 24 October 2004.
Provide comments to Dwight Moore at mooredwi@emporia.edu.
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