TKGS Prelim paper 2

Tanjong Katong Girls’ School 1 Sec 4 Preliminary Examination 2025 TANJONG KATONG GIRLS’ SCHOOL PRELIMINARY EXAMINATION SECONDARY FOUR EXPRESS BIOLOGY CANDIDATE NAME CLASS INDEX NUMBER BIOLOGY 6093/02 Paper 2 18 August 2025 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and register number on all the work you hand in. Write in dark blue or black pen. You may use a HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A Section B Total / 80 This document consists of 22 printed pages.

Tanjong Katong Girls’ School 2 Sec 4 Preliminary Examination 2025 Section A Answer all questions. 1 A student investigates the uptake of potassium ions by root tissue. A root is cut into four discs of uniform size. Each disc is added to an equal volume of a solution containing a fixed potassium ion concentration. The experiment is carried out in different oxygen concentrations. The results are shown in Table 1.1. Table 1.1 oxygen concentration / arbitrary units 0 4 11 20 rate of potassium ion uptake / arbitrary units 7 27 92 100 (a) State, with a reason, one other variable that should be kept constant. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [2] (b) Using the information in Table 1.1, state and explain the main method by which potassium ions are taken into the root. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [3]

Tanjong Katong Girls’ School 3 Sec 4 Preliminary Examination 2025 (c) Suggest why the investigation uses four discs from one root tissue instead of one disc each from four root tissues. …………………………………………………………………………………………….. …………………………………………………………………………………………….. …………………………………………………………………………………………. [2] (d) The tissue given 0 arbitrary units of oxygen is then placed in conc