2025 YIJC [H2] Prelim P2 (A) With EXAMINER REPORT

YISHUN INNOVA JUNIOR COLLEGE JC2 PRELIMINARY EXAM Higher 2 NAME INDEX NO CG BIOLOGY Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/02 9 SEPTMBER 2025 2 hours READ THESE INSTRUCTIONS FIRST Write your name, index no. and CG on this cover page. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, 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 At the end of the examination, submit booklets A, B and C separately to the invigilator. This document consists of 23 printed pages and 1 blank page. For Examiner’s Use Section A 1 2 3 4 5 6 7 8 9 10 11 Total 100 ANSWERS

2 ©YIJC 9744/02/PE/2025 [Turn over] Answer all questions. 1 The uptake of glucose and the nutrient coupled transcellular ions traffic across epithelial cells in the small intestine has been an ongoing topic in physiological research. Fig. 1.1 shows how protein A and protein B work together for the uptake of glucose across the cell surface membrane. Fig. 1.1 (a) With reference to Fig. 1.1, (i) identify Protein A Sodium Potassium Pump (Na+–K+ pump) or protein pump / transport protein / carrier protein / channel protein [1] Examiner’s Comment: As Fig 1.1 does not provide sufficient information to conclude it is ATP pump. Transmembrane and integral protein are rejected as these answers are too vague in comparison to the information provided. (ii) describe how glucose enters the cell 1 (Idea of ATP Hydrolysis): Protein A facilitate the movement of K + and Na+ through the cell membrane where ATP is used /converted to ADP 2 (Idea of ion concentration gradient): A concentration gradient is created where there is more Na+ outside of the cell and more K+ within the cell 3 (Idea of simple diffusion of glucose): Na+ will enter the cell with glucose via protein B [3] (R) chemiosmosis, no ATP is generated. (R) concentration gradient of glucose (R) if student identify wrongly: i.e. W – potassium and X – sodium. Max:1mark Examiner’s Comment: Many students failed to refer to Fig1.1 to explain how glucose is brought into the cell, regurgitation of content resulted in the lost of marks. Protein A Protein B glucose 2 K+ 3 Na+ Outside of cell High Na+ concentration Low K+ concentration High glucose concentr