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Đề thi INTERNATIONAL BIOLOGY OLYMPIAD lần thứ 20

THEORETICAL TEST: PART A GENERAL INSTRUCTIONS 1. Open the envelope after the start bell rings. 2. A set of questions and an answer sheet are in the envelope. 3. Write your 4-digit student code in every student code box. 4. The questions in Part A have only one correct answer. Mark the correct answer with “X” on the Answer Sheet clearly, as shown below. | ENVELOPE COVER SHEET Student Code __ 20th INTERNATIONAL BIOLOGY OLYMPIAD Tsukuba JAPAN 12th - 19th July 2009 THEORETICAL TEST PART A Time available 120 minutes GENERAL INSTRUCTIONS 1. Open the envelope after the start bell rings. 2. A set of questions and an answer sheet are in the envelope. 3. Write your 4-digit student code in every student code box. 4. The questions in Part A have only one correct answer. Mark the correct answer with X on the Answer Sheet clearly as shown below. No. A B C D E F A0 X 5. Use pencils and erasers. You can use a scale and a calculator provided. 6. Some of the questions may be marked DELETED . DO NOT answer these questions. 7. Stop answering and put down your pencil IMMEDIATELY after the end bell rings. IBO-2009 JAPAN THEORETICAL TEST Part A Student Code 20th INTERNATIONAL BIOLOGY OLYMPIAD Tsukuba JAPAN 12th - 19th July 2009 THEORETICAL TEST PART A Time available 120 minutes GENERAL INSTRUCTIONS 1. Write your 4-digit student code in every student code box. 2. The questions in Part A have only one correct answer. Mark the correct answer with X on the Answer Sheet clearly as shown below. No. A B C D E F A0 X 3. Use pencils and erasers. You can use a ruler and a calculator provided. 4. Some of the questions may be marked DELETED . DO NOT answer these questions. 5. The maximal points of Part A is 81 1.5 point each question . 6. Stop answering and put down your pencil IMMEDIATELY after the end bell rings. GOOD LUCK 1 IBO-2009 JAPAN THEORETICAL TEST Part A Cell Biology A1. Which treatment is most effective in breaking as many hydrogen bonds as possible in an aqueous solution pH 7.0 of 1 mg mL DNA and 10 mg mL protein A. Addition of hydrochloric acid to make the pH 1.0. B. Addition of sodium hydroxide solution to make the pH 13.0. C. Addition of urea to a concentration of 6 mol L. D. Addition of sodium dodecyl sulfate a detergent to a concentration of 10 mg mL. E. Heating the solution to 121 C. F. Freezing the