GMSS 2018 Bio Prelim P2 QP

1 GMS(S)/BiologyP2/Prelim/2018/4Exp GMS(S)/BiologyP2/Prelim/2018/4Exp Candidate Name Class Index Number ____________________________________________________________________ BIOLOGY Paper 2 6093/02 Sec 4 Express Additional materials:Nil 1 hour 45 minutes Setter: Mrs Cheryl Tang 20 Aug 2018 READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black penin both sides of the paper. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions in the spaces provided on the question paper. Section B Answer allthe questions. Write your answers in the spaces provided on the Question Paper. Write an E(for Either) or an O(for Or) next to the number 10in the grid below to indicate which question you have answered. You are advised to spend no longer than one hour on Section A and no longer than 45 minutes for Section B. At the end of the examination, hand in the question paper. The number of marks is given in brackets [ ] at the end of each q u e s t i o n o r p a r t question. For Examiner’s Use Section A Section B 8 9 10 Total This document consists of 20printed pages and 2blank pages. [Turn over Geylang Methodist School (Secondary) Preliminary Examination 2018 www.KiasuExamPaper.com 298

2 GMS(S)/BiologyP2/Prelim/2018/4Exp Section A (50 marks) Answer allquestions. Write your answers in the spaces provided. 1 A group of students investigated the effect of soaking small onion bulbs in different concentrations of sodium chloride solution. They peeled off the outer papery leaves of the onion bulbs and divided the onions into 6 batches, e a c h w i t h 1 0 onions. The onions were surface dried with paper towels and weighed. The mean mass of the onions in each batch was calculated. The onions were then left in sodium chloride solutions for three hours. After three hours the students surface dried the onions and weighed them again. Their results are given in Table 1.1. Table 1.1 concentration of sodium chloride solution / g dm-3 mean mass of onions / g percentage change in mass/ %before soaking after soaking for 3 hours 0 147 173 +17.7 25 153 165 +7.8 50 176 172 -2.3 100 154 149 -3.2 150 149 142 -4.7 200 183 175 (a) (i) Explain why the students calculated the percentage change in mass of the onions. [2] (ii) Calculate the percentage change in mass of the onions that were in the most concentrated solution of sodium chloride. Show your working. Write your answer in Table 1.1. [1] www.KiasuExamPaper.com 299

3 GMS(S)/BiologyP2/Prelim/2018/4Exp (b)The students plotted a graph of the results as shown in Fig. 1.1. Fig. 1.1 (i) Complete the graph using your answer to (b)(i). [1] (ii) Use the graph in Fig. 1.1 to estimate the concentration of the sodium chloride solution that has the same water potential as the onions. [1] (c) Using the term water potential, explain why