2022 HCI JC2 H2 Biology Prelims Paper 2 QP

This document consists of 30 printed pages. © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 21S7__ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/02 22 August 2022 2 hours INSTRUCTIONS TO CANDIDATES Write your name, CT group, Centre number and index number in the spaces provided at the top of this cover page. There are eleven questions. Answer all questions in the spaces provided on the Question Paper. INFORMATION FOR CANDIDATES 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. You are reminded of the need for good English and clear presentation in your answers. For Examiners' Use 1 / 9 2 / 9 3 / 11 4 / 9 5 / 10 6 / 10 7 / 11 8 / 11 9 / 9 10 / 5 11 / 6 Total / 100

2 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 QUESTION 1 Fig. 1.1 shows the structure of amylose, a component of the polymer starch. Fig. 1.1 (a) Describe the main features of amylose visible in Fig. 1.1. ………………………………………...………………………..……………..…………..……… ……………………………………………………………………………………………..……… ……………………………………………………………………………………………..……… …………………………………………………………………………………………………..… …………………………………………………………………………………………..……. [2] (b) Explain how the structure of amylose makes it suitable for its function. ………………………………………...………………………..……………..…………..……… ……………………………………………………………………………………………..……… ……………………………………………………………………………………………..……… …………………………………………………………………………………………………..… …………………………………………………………………………………………..……. [2]

3 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 Single-stranded amylose in an aqueous solution gradually forms a double helix. (c) Suggest how the double helix structure of amylose is formed. ……………………………………………………………………………………………..……… …………………………………………………………………………………………………..… …………………………………………………………………………………………..……. [1] Collagen is another polymer that can be found in living organisms. (d) (i) State two ways in which the structure of collagen differs from the structure of starch. ……………………………………………………………………………………………..…… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… ………………………………………………………………………………………………….. …………………………………………………………………………………………..…. [2] (d) (ii) Explain how one of the differences stated in (d)(i) allows collagen to perform its function. ………………………………………...………………………..……………..…………..……… ……………………………………………………………………………………………..……… ……………………………………………………………………………………………..……… …………………………………………………………………………………………………..… …………………………………………………………………………………………..……. [2] [Total: 9]

4 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 QUESTION 2 Cell surface membranes are involved with the movement of substances into and out of cells. Calcium pumps in cell surface membranes maintain a concentration of calcium ions inside the cytoplasm that is a thousand times lower than outside the cell. Fig. 2.1 shows the movement of calcium ions across a cell surface membrane. Fig. 2.1 (a) With reference to Fig. 2.1, (i) explain why calcium ions do not pass through the phospholipid bilayer. ………………………………………………………………..……………..…………..……… …………………………………………………………………………………………..……… ……………………………………………………………………………………………..…… ………………………………………………………………………………………………..… ………………………………………………………………………………………..……. [2]

5 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 (ii) state and describe the process by which calcium ions are moved across the membrane. …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..……………… …………………………………………………………………………………..…………. [4] (b) With reference to the fluid mosaic model, discuss how high temperature affects membrane permeability. …………………………………………………………………………………………..………… ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… …………………………………………………………………………………………………..… …………………………………………………………………………………………………….. …………………………………………………………………..………………………………… ……………………………………………………………….………………………………. [3] [Total: 9]

6 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 QUESTION 3 (a) State the central dogma of molecular biology. ……..…………………………………………………………..………………………………...... …...…..…………………………………………………………..……………………………...... ………….…….…………………………………………………..……………………………...... …………….….……………………………………………………..…………………………...... ………………..………………………………………………………..………………………...... …………………..………………………………………………………..……………………...... …………………….……………………………………………………………………………. [3] Telomeres are repeating sequences of bases locate d at the ends of DNA molecules. These repeating sequences do not code for proteins. The enzyme telomerase ensures that telomeres do not shorten each time DNA is replicated. Fig. 3.1 shows the end of a DNA molecule during replication. DNA polymerase cannot attach to the region labelled X, so it cannot complete the synthesis of the new strand without the action of telomerase. Fig. 3.1 Telomerase synthesises additional lengths of DNA that are added to the telomer e. These additional lengths are used by DNA polymerase to complete the process of replication. Fig. 3.2 is an enlarged view of region X to show the action of the enzyme telomerase. Fig. 3.2

7 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 Telomerase contains a short length of RNA that acts as a template for the synthesis of DNA as shown in Fig. 3.2. (b) Explain how a molecule of telomerase synthesises additional lengths of DNA. ……………………………………………………………………..……………………………… ………………………………………………………………………..…………………………… …………………………………………………………………………..………………………… ……………………………………………………………………………..……………………… ………………………………………………………………………………..…………………… …………………………………………………………………………………..………………… ……………………………………………………………………………………..……………… ………………………………………………………………………………………..…………… …………………………….…………………………………………………………..……… [4]

8 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 2 (c) Explain why the action of telomerase challenges the central dogma of molecular biology. …………………………………………………………………………………………….............. ………………………………………………….………………………………………................ ……….……………………………..…………………………………………………….............. …………..…………………………..…………………………………………………………...... ………………..………………………..………………………………………………………. [2] (d) Telomerase is not present in prokaryotic cells. Suggest why prokaryotes do not have telomerase. …………………………………………………………………………………………….............. ………………………………….…………………………………………………………............. …………………………………….……………………………………………………................ ……………………………………….….…………………………………………………..…...... ………………………………………….……………………………………………………… [2] [Total: 11]

9 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Pre