2023 JC1 H1 EOY P2 QP

1 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [TURN OVER DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN READ THESE INSTRUCTIONS FIRST Write your name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. 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 any 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 Examiner’s Use Section A / 15 Section B 1 / 6 2 / 8 3 / 8 4 / 13 Section C Essay / 15 Total / 65 TEMASEK JUNIOR COLLEGE PROMOTIONAL EXAMS 2023 Higher 1 CANDIDATE NAME CIVICS GROUP / 2 3 BIOLOGY 8876 SECTION B STRUCTURED QUESTIONS FRIDAY, 22 SEPTEMBER 2023 2 hours 10 minutes Candidates answer on the Question Paper. No Additional Materials are required. This document consists of 10 printed pages and 2 blank pages.

2 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN Answer all questions. 1 Fig.1.1 shows a cell releasing insulin in response to glucose uptake. The uptake of glucose through Glucose Transporter 2 (GLUT2) causes a rise in ATP levels in the cell. This closes the potassium channel and in turn causes calcium channel to open. The influx of calcium ions leads to the release of insulin. Fig. 1.1 (a) (i) With reference to Fig. 1.1., describe two differences in the way insulin and glucose are transported across the cell surface membrane. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. …………….………………………………………………….…..…………………………….…. [2] (ii) Explain how the membrane proteins in Fig. 1.1 are able to transport the substances across the cell surface membrane. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. …………….………………………………………………….…..…………………………….…. [2]

3 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [TURN OVER DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN (b) Suggest with a reason how a secretory cell will differ in terms of organelles from a non-secretory cell. .…………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] Fig. 1.2 shows an organelle in a eukaryotic cell. Fig. 1.2 (c) With reference to Fig. 1.2; explain why the organelle cannot be a lysosome. .…………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] [Total: 6]

4 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 2 (a) Fig. 2.1 shows the photomicrograph during one stage of mitosis occurring in a root tip cell of a diploid flowering plant. The diploid number is 14. Fig. 2.1 Complete Table 2.1 to show the number of chromosomes found in the cell at the end of a given stage of the cell cycle. Table 2.1 [2] (b) Outline one difference between a pair of homologous chromosomes and sister chromatids of a chromosome. .…………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] stage no. of chromosomes per cell G1 14 S phase cytokinesis

5 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [TURN OVER DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN (c) (i) Describe the characteristics of embryonic stem cells. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. …………….………………………………………………….…..…………………………….…. [2] (ii) State the challenges of using embryonic stem (ES) cells for research or medical treatment and explain how induced pluripotent stem cells (iPSCs) may overcome each of the se challenges. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. …………….………………………………………………….…..…………………………….…. [3] [Total: 8]

6 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 3 A student carried out an investigation into the mass of product formed in an enzyme-controlled reaction at three different temperatures. Only the temperature was different for each experiment. The results are shown in Fig. 3.1. Fig. 3.1 (a) Use your knowledge of enzymes to explain (i) why the initial rate of reaction was highest at 55 °C; ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. …………….………………………………………………….…..…………………………….…. [2] (ii) the shape of the curve for 55 °C after 20 minutes. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. ……….……………………………………….….…………………………………………………… …………………………………………………………….………………………………………….. …………….………………………………………………….…..…………………………….…. [3] Time / minutes Mass of product formed / mg

7 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN [TURN OVER DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN (b) Explain why the curves for 27 °C and 37 °C level out at the same value. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] The enzyme is found to have the structure as shown in Fig. 3.2. Fig. 3.2 (c) Describe structure A found in the enyzme. …………………….………………………………………………………………………………………… …………………….………………………………………………………………………………………… …………………….………………………………………………………………………………………… …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2] [Total: 8]

8 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 4 A diagram of a chromosome from a dividing cell is shown in Fig. 4.1. Fig. 4.1 (a) Before a cell divides, DNA replication takes place via semi-conservative replication. State two ways how DNA replication differs from transcription. ….…………………………………………………………………………………………………………… …….………………………………………………………………………………………………………… .…………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2] (b) The chromosome shown in Fig. 4.1 consists of one long DNA molecule associated with histone proteins. Name one stage of mitosis in which a chromosome would have the same general structure as the chromosome shown in Fig. 4.1. .……………….…..……………………………………………………………………………………… [1] (c) Name the stage in the cell cycle during which the cell divides to produce two genetically identical daughter cells. .……………….…..……………………………………………………………………………………… [1] Blood stem cells are actively dividing cells found in the bone mar