JPJC 2023 J2 H2 BI Prelim P2 ANS

9744 / 02 [Turn over NAME : CLASS : JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examination 2023 BIOLOGY Higher 2 9744/02 29 August 2023 Paper 2 Structured Questions 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your class and name 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. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 2 3 4 5 6 7 8 9 10 11 Total This document consists of 19 printed pages and 1 blank page.

2 JPJC/JC2 H2 Biology/Prelims/2023 Answer all questions. 1 Fig. 1.1 shows a diagram of a cell surface membrane. Fig. 1.1 (a) The structure of the cell surface membrane is described as a fluid mosaic. Explain what is meant by the term fluid mosaic. ............................................................................................................................... [2] Fluid: 1. “Fluid” means that the phospholipids and proteins are free to move within the membrane ; 2. Phospholipids are held by weak hydrophobic interactions and hence move about rapidly by diffusion in their own layers ; [Max 1] Mosaic: 3. Proteins are embedded within the phospholipid bilayer in a random manner ;

3 JPJC/JC2 H2 Biology/Prelims/2023 [Turn over (b) Outline the functions of the following components of the cell surface membrane. K ................................................................................................................................. L ................................................................................................................................. M ................................................................................................................................ N ................................................................................................................................. [4] 1. K: channel proteins that help to regulate the movement of polar molecules or charged ions across membranes, via facilitated diffusion ; 2. L: involved in cell- cell recognition where the carbohydrate chain of (glyco)proteins serves as markers/identification tags, that distinguishes one cell from another ; 3. M : the hydrophobic core of membranes acts as a selective barrier , restricting the movement of charged ions or polar molecules across th