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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