ACJC 2023 H2 Bio Prelim Paper 2_Answers

This document consists of 29 printed pages and 2 blank pages. [Turn over A Anglo-Chinese Junior College JC2 Biology Preliminary Examination Higher 2 CANDIDATE NAME FORM CLASS TUTORIAL CLASS INDEX NUMBER BIOLOGY Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/02 23 August 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your Name, Class and Index number in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiners’ use only 1 / 8 2 / 11 3 / 10 4 / 8 5 / 11 6 / 10 7 / 10 8 / 12 9 / 10 10 / 5 11 / 5 Total / 100

2 Anglo-Chinese Junior College 2023 J2 H2 9744 Paper 2 Preliminary Examination For Examiner Use Answer all questions. 1 The cell surface membranes of different cells have a similar basic structure, but the proportions of the various molecules present vary between membranes and even between the inner and outer layers of a membrane. Fig. 1.1 shows the structure of a typical cell surface membrane. Fig. 1.1 (a) With reference to Fig. 1.1, (i) identify molecules A and B and describe their respective functions. A: Cholesterol; Function: Regulates/maintains membrane fluidity and permeability; B: Channel protein; Function: Provides hydrophilic channel for charged ions/ polar molecules to move across the membrane; R! polar ions [M] …………………………………………………………………………………………............ [4] (ii) State one way in which the outer layer of the membrane is different from the inner layer. Presence of glycoprotein / glycolipid in the outer layer of membrane where none occur on the inner layer of the membrane; A! oligosaccharides face outwards …………………………………………………………………………………………............ [1] (iii) Describe the significance of the difference stated in your answer for (a)(ii). Oligosaccharides on glycoprotein/glycolipid facing exterior of cell involved in: 1. Cell-cell adhesion; 2. Cell-cell recognition; 3. Acting as receptors to allow signal molecules to bind; no ecf. …………………………………………………………………………………………............ [1]

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