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GENETICS 311212
First Midterm Exam.
Spring 2002
Name: ………………………………………………..
I.
Multiple Choices:
1. During which of the following stages of cell cycle would a
chromosome consist of only one single chromatid?
a. G1
c.G2
b. Mitotic prophase
d. All of the above
2. Which of the following statements applies to homologous chromatids?
a. They attached to the same centromere
b. They are genetically identical
c. They contain the same gene in the same order but may have
different alleles of the same genes
d. More than one of the above statement applies to homologous
chromatids
3. Crossing over between homologous chromosomes occurs at which of
the following stages of meiosis?
a. S phase
c. Prophase I
b. Metaphase I
d. Prophase II
4. How many autosomes are present in a normal human primary
spermatocyte?
a. 22
c. 23
b. 44
d. 46
5. Which of the following events occurs during mitosis but not meiosis?
a. Pairing of homologous chromosomes
b. Crossing over between homologous chromosomes
c. Segregation of sister chromatids
d. None of the above
6. Cells in G2 stage of cell cycle have --------- as cells of the same species
in the G1 stage.
a. Twice as many chromosomes
b. Twice as many chromatids
c. Half as many chromatids
d. The same number of chromatids
7. The following is a list of mitotic events out of order
A. Chromosome align in the midplate of the cell
B. Kinetochores begins attaching to the spindle fibers
C. Nuclear membrane reforms, chromosome decondense
D. Chromosome condense, centrosomes migrates to
opposite sides of the nucleus
E. Sister chromatids separate, move to opposite poles
What is the correct order of events?
a. BDACE
c. DABEC
b. DBAEC
d. None of the above
8. In the dihybrid cross AaBb x aabb, how many heterozygous for both
gene pairs are found among the F1 offspring?
a. One
c. Two
b. Three
d. Four
9. Among the dihybrid below which eill give a 1:1 ratio?
a. Aa Bb x AaBb
c. AaBb x aabb
b. AaBB x aaBB
d. Aabb x aaBB
10. Assuming that in Guinea pigs, dark brown fur (B) is dominant to black
fur (b). If you mate heterozygous black guinea pigs with a homozygous
brown guinea pigs, what proportion of the progeny will be black?
a. ¼
c. ½
b. ¾
d. none
11. Which of the following ratios indicates a lethal gene?
a. 2:1
c. 3:1
b. 1:2:1
d. 1:1
12. If an individual has the genotype AaBBDdEeFfGghh, how many
different types of gametes can be produced?
a. 32
c. 64
b. 27
d. (1/2)5
13. In the individual above, which of the following chromosome
complements may be found in one of his sperm cells?
a. ADEFh
c. ABDEFGH
b. AbdEfGh
d. None of the above
14. Which of the following crosses about the color of the snapdragons is
expected to produce only pink color in the offspring?
a. Red x red
c. Red x pink
b. White x pink
d. Pink x pink
15. Which of the following can be excluded as the possible father of a type
O, Rh+, MN offsprig when the maternal phenotype is type O, Rh-,
MN?
a. AB, Rh+, M
c. A, Rh+, MN
b. B, Rh-, MN
d. O, Rh-, N
II.
Fill in the blanks:
1. A --------------------------- is a sequence of nucleotides that are basic
unit of biological information
2. A chromosome with two arm of equal length ------------------------3. Another name for normal gene ----------------------------4. The chromosome structure to which spindle fiber attached during
mitotic division ------------------------------5. The percentage of individuals of a genotype that show the expected
phenotype is called ----------------------------
III.
Answer the following questions:
1. In a mating ABRh+Rh-MN x AB Rh+Rh-MN, what is the probability
that the first child will have the phenotype :
a. Arh-MN
b. ABRh+M
2. Below is a pedigree of a human genetic disease in which affected
individuals are solid colored:
a. What is the genotype of 1 and 4
b. What are the offspring of the cousin marriages 2 x 3
and 1 x 4
3. In sweet peas, gene C and P are necessary for purple flowers, in the
absences of either or both genes the flower are white . Give the
expected colors and proportions of offspring from the following
crosses:
a. Ccpp x ccPp
b. Ccpp x CcPp