2012 Exam 1 Key

2012 Exam 1 Key - Spring 2012 Biology 241 Introduction to...

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Spring 2012 Biology 241 – Introduction to Genetics and Molecular Biology Midterm I (100 points) 2/14/2012 Name:____KEY_____________________________ Purdue ID:__________________________________ Question 1: (20) Question 2: (10) Question 3: (10) Question 4: (10) Question 5: (8) Question 6: (6) Question 7: (8) Question 8: (8) Question 9: (6) Question 10: (4) Question 11: (5) Question 12: (5) Total:
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Biol241 2012 Name:__________________________ 1 1. Multiple-choice questions (10 points, 2 points each; please circle the correct answers) . 1) Diseases such as Myotonic Dystrophy exhibit earlier onset and increased phenotypic severity in successive generations. This is caused by: a. The expansion of tri-nucleotide repeats in the disease-causing genes. b. The random inactivation of X-linked disease-causing genes. c. The formation of heteroduplex at the disease-causing genes. d. The methylation of cytosines in CG islands near the disease-causing genes. 2) With recessive epistasis, a likely ratio resulting from a dihybrid cross would be: a. 9:3:4 b. 9:7 c. 12:3:1 d. 9:3:3:1 3) With complementary interaction, a likely ratio resulting from a dihybrid cross would be: a. 9:3:4 b. 9:7 c. 12:3:1 d. 9:3:3:1 4) Which of the following events during meiosis is the cause for the non-viable progeny in the phenomena of semisterility. a. A single crossover within the inverted region of a paracentric inversion. b. A single crossover within the inverted region of a pericentric inversion. c. Segregation of homologous chromosomes in a triploid organism. d. Adjacent segregation of reciprocal translocated chromosomes.
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Biol241 2012 Name:__________________________ 2 5) In analyzing DNA from a species, you determine that the base composition consists of 20% adenines. What is likely the percentage of guanines in this organism? a. 10%. b. 20%. c. 30%. d. 40%. 6) In the nucleus of a somatic cell from a Klinefelter syndrome individual, you are likely to find: a. 0 Barr body. b. 1 Barr body. c. 2 Barr bodies. d. 3 Barr bodies. 7) The following result describes the absorbance of UV light (260nm) by three nucleic acid species at increasing temperature. Assuming that they are all equal in length, what can you conclude about them from these data? a. A is double stranded. b. B contains more G-C base pairs than A. c. C contains more G-C base pairs than B. d. B contains more G-C base pairs than C. Temperature (°C) 60 70 80 OD 260 absorbance A A B B C C
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Biol241 2012 Name:__________________________ 3 8) Familial Down syndrome is usually caused by: a. Nondisjunction of chromosome 21 during meiosis. b. A single crossover within a pericentric inversion of chromosome 21. c. Robertsonian translocation between chromosomes 21 and 14.
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2012 Exam 1 Key - Spring 2012 Biology 241 Introduction to...

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