quiz1s - MIT Biology Department 7.012 Introductory Biology...

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7.012 Quiz 1 Answers A 87 ~25% of test takers B 73 ~34% of test takers C 60 ~24.3% of test takers D 50 ~10.1% of test takers F 49 ~6.5% of test takers Regrade requests (with a note attached indicating the problem and part you want looked at) Monday 10/04/04 Question Value Score 1 16 2 20 3 16 4 16 5 15 6 17 100 MIT Biology Department 7.012: Introductory Biology - Fall 2004 Instructors: Professor Eric Lander, Professor Robert A. Weinberg, Dr. Claudette Gardel
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Question 1 a) Match each boxed chemical interaction in the structures below with the appropriate description. 10 pts _____B_____ peptide bond _______E___ ionic bond ____A_____ van der Waal’s interaction ______D____ phosphodiester bond _____C_____ hydrogen bond C A B D E 2
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Name________________________________ b) Which one of the following structural features is NOT based on hydrogen bonds? Circle all that apply. 3 pts i) complementary base pairing in DNA ii) protein primary structure iii) protein secondary structure iv) complementary base pairing in RNA c) Your friend tried to remove some writing on a plastic box. He used a napkin dampened with water, which did not work. Then as you advised, he used ethanol (instead of water), and successfully removed the writing. Circle why ethanol was better than water in this case. 3 pts [formula of ethanol: CH 3 -CH 2 -OH] i) Ethanol has a greater surface tension, so it extracts the ink molecules better from the plastic. ii) Ethanol can form hydrogen bonds with the ink molecules. iii) One end of ethanol is non-polar. This makes ethanol a better solvent for the ink molecules. iv) Ethanol is more hydrophilic, so it washes off the writing more efficiently. 3
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Question 2 a) Fill in the percentages. If the value can’t be determined write “ND”. 6 points i) According to Chargaff’s rule, if the DNA content of a cell was composed of 15% A, then C would make up ____ 35 ______% , G would make up ___ 35 ______%, and T would make up____1 5% _______ % of the cell’s DNA. ii) If the RNA content of a cell was composed of 15% A, then C would make up ____ ND ______%, G would make up ____ ND _____%, and T would make up____ 0% _______ % of the cell’s DNA. b) Match the following with all that apply. 6 points A. Lowers the activation energy of a reaction ___ ace ___ Lactase B. Raises the activation energy of a reaction C. Breaks down milk sugar to galactose and glucose ____ ag ___ ribozyme D. Lipid E. Protein ___ f ______ “TheTransforming Principle” F. DNA G. RNA c) Fill in the blanks. 2 pts each i) DNA is synthesized in the _________ direction. Circle one.
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quiz1s - MIT Biology Department 7.012 Introductory Biology...

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