VJC_H3_BIO_2015_MS

1 VICTORIA JUNIOR COLLEGE BIOLOGY DEPARTMENT JC2 PRELIMINARY EXAMINATIONS 2015 Higher 3 VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE VICTORIA JUNIOR COLLEGE CANDIDATE NAME CLASS INDEX NUMBER BIOLOGY 9815/01 28 September 2015 Additional Materials: Answer Paper 2 hours 30 minutes READ THESE INSTRUCTIONS FIRST Write your CLASS/ INDEX no. and name on all the work you hand in. Write in dark blue or blue pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use any staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer three out of four questions. Section C Answer the question. At the end of the examinations, 1. Fasten all your work securely; 2. Circle the number of the section B question you have answered in the grid opposite. The number of marks is given in brackets [ ] at the end of each question or part question. This paper consists of 10 printed pages, including the cover page. For Examiner’s Use Section A 1 2 3 4 5 Section B 6 7 8 9 Section C 10 Total Mark Scheme

2 Section A Answer all questions in this section. Key: (;) means ½ mark and (;;) means 1 m 1 (a) Fig.1 shows GDP in the binding site of a G protein. Fig. 1 (i) With reference to Fig. 1, describe the types of interactions between GDP and the amino acids that make up the binding site. [3] • Ionic interaction – between side chains of Lys and Arg and the phosphate group of GDP;; • Hydrogen bonds – between side chains of Asp and Glu with the ribose sugar of GDP;; • Hydrogen bond – between side chain of Tyr with the –NH2 group of guanosine/ nitrogenous base of GDP;; (ii) A mutation results in the change of the amino acid from Arg to Asp at the binding site. A similar change occurs within the protein core of G protein. Discuss the difference, if any, the effect of these mutations on the function/ activity of the protein.