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GENETICS 311212
Second Midterm Exam.
Spring 2002
Name: ………………………………………………..
I.
Multiple Choices:
1. A person with no Barr bodies is (are):
a. Normal male
c. Jacob syndrome
b. Turner syndrome
d. All of the above
2. If you are a male, your X chromosome contains genes derived from:
a. Your paternal grandfather only
b. Your maternal grandfather only
c. Both your paternal and maternal grand father
d. Both your maternal grandfather and grandmother
3. Red green color blindness is controlled by an X chromosomal gene in
humans. A normal man and a woman whose fathers are both color
blind marry. What is the probability that their first child be color blind?
a. 1/2
c. 1/4
b. 1/8
d. None of the above
4. The karyotype 47,XX,+18 represent:
a. Edward syndrome
c. Patau syndrome
b. Cri du chat syndrome
d. Down syndrome
5. A cross between a white-eyed female fruit fly and a red-eyed male
would generate which of the following types of progeny?
a. Red-eyed females and white-eyed males
b. White-eyed males and red-eyed females
c. All red-eyed males and a 50-50 mixtures of white-eyed and
red-eyed females
d. None of the above
6. Which of the following does not belong to the group:
a. Jacob syndrome
b. Klienfelter syndrome
c. Down syndrome
d. Triple X syndrome
7. Which sex chromosomes are limited to only one sex:
a. X and Z
c. X and W
b. Y and W
d. Y and Z
8. The R/r and S/s genes are linked and 10 map units apart. In the cross
Rs/rS x rs/rs what fraction of the progeny will be RS/rs?
a. 5%
c. 10%
b. 25%
d. 40%
9. Which of the following is not an aneuploidy?
a. Monosomy
c. Tetraploidy
b. Trisomy
d. Mosaic
10. Traits that expressed only in one sex and are under hormonal control
are called:
a. Sex influenced traits
b. Sex limited traits
c. Sex linked traits
d. None of the above
11. The pairwise map distance for four linked genes are as follows:
A-B =22, B-C =7, C-D= 9, B-D =2, A-D =20, A-C =29 m.u. What is
the order of these four genes?
a. ABCD
c. ADBC
b. ABDC
d. CADB
The following information applies to problems 12 to 14. In fruit flies, the
recessive pr and cm mutation causes brown and bright-red eyes,
respectively (wild type flies have brick-red eyes). The double mutant pr cn
combination has orange eyes. A female who has wild-typed eyes is crossed
to an orange-eyed male. The progeny have the following distribution of
eye colors:
Wild-type
8
Brown
241
Bright-red
239
Orange
12
12. Which classes are the parental types?
a. Wild type & orange
c. Brown & bright red
b. Bright red & orange
d. Wild type & brown
13. What is the genotype of the mother of these progeny?
a. Prcn/+ +
c. + cn/ + cn
b. + cn/ pr +
d. pr +/ pr +
14. What is the map distance between the pr and cn genes?
a. 20 m.u.
c. 4 m.u.
b. 2 m.u.
d. None of the above
15. The map of a chromosome interval is A 10 B 40 C. From the cross
Abc/aBC x abc/abc, how many double crossovers would be expected
out of 1000 progeny?
a. 80
c. 10
b. 20
d. 40
II.
Answer the following questions:
1. A female fruit fly with signed bristles was mated with a male from a
true breeding wild type stock with long bristles. All of the F1 females
had wild type bristles and all of F1 males had signed bristles. If the F1
flies intercrossed, what would you expect the ratio of long to singed
bristles in the F2 flies to be?
2. What is the mechanism that may produce the following:
a. 47,XYY
b. 92,XYYY
{Use drawing to explain your answers}
3. In Drosophila , the genes y, f and v are all X linked. Y f v female are
crossed to a wild type males and the F1 female are test-crossed. The F2
are distributed as fellow:
y f v 3210
y f + 72
y+ v 1024
y + + 678
+ f v 690
+ f + 1044
+ + v 60
+ + + 3222
10,000
a. Determine the linkage arrangement of these three genes and calculate the map
distance.
b. Calculate the coefficient of coincidence.
c. State what a coefficient of 0.5 would mean