SAJC 2023 H2 BIO P2 QP

1 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations Civics Group Index Number Name (use BLOCK LETTERS) ST. ANDREW’S JUNIOR COLLEGE 2023 JC2 PRELIMINARY EXAMINATIONS H2 BIOLOGY 9744/2 Paper 2 Monday 28 th August 2023 2 hours Materials: Question Paper Set A and Set B READ THESE INSTRUCTIONS FIRST Write your name, civics group and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagram, graph or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. Write your answers in the spaces provided on the question paper. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiners’ Use 1 /13 2 /10 3 /12 4 /12 5 /14 6 /9 7 /11 8 /9 9 /5 10 /5 Total /100 This document consists of 27 printed pages and 0 blank page. [Turn over H2

2 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations QUESTION 1 Fig. 1.1 is an electron micrograph that shows part of a eukaryotic cell. Fig. 1.1

3 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations (a) Organelle B is made of two types of molecules. (i) Name the molecules in organelle B and state the process and location where each molecule is synthesized, by completing the table below: Organelle B Molecule 1 Molecule 2 Name Process Location [3] (ii) Identify the organelle B in Fig. 1.1 and state one function of this organelle. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………[2]

4 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations (b) Collagen is a protein produced by cells and is the most common structural protein, due to its high tensile strength, in vertebrates. (i) To form collagen, many of the amino acids such as proline and lysine are modified by the addition of a hydroxyl group on its side chain to form hydroxyproline and hydroxylysine residues, respectively. Vitamin C is necessary in aiding this conversion of proline and lysine to hydroxyproline and hydroxylysine. Vitamin C works by preventing the inactivation of two key enzymes, lysyl and prolyl hydroxylas, in collagen biosynthesis. Fig. 1.2 shows the synthesis of collagen. Production of tropocollagen starts with procollagen. Procollagen, once secreted outside the cell, will be cleaved at C and N terminus to form tropocollagen. Fig. 1.2 Describe how the procollagen is synthesized and secreted out of the cell to be assembled into collagen. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………[6]

5 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations (ii) Cellulose is present in plants and functions as a suitable cell wall material. Cellulose is made up of cellulose microfibrils which are formed from cellulose molecule. Each cellulose molecule is a polymer of glucose. Describe the structure of cellulose molecule. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………[2] [Total: 13]

6 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations QUESTION 2 Chemotherapy is used in the treatment of cancers. Common side effects during chemotherapy treatment include fatigue, hair loss, infection, etc. While the survival rate has increased due to chemotherapy for some cancers, e.g breast cancer, the quality of life has decreased because of the side effects of chemotherapy. For some patients, fatigue may persist for months or even years after the end of cancer treatment, thus affecting the physical functioning and mental health of these patients. Various toxins are being developed as alternatives to cancer treatments, and bee venom is drawing attention as one of them. Several studies have demonstrated one of the components in bee venom, melittin, has anti-cancer effects. Melittin is a polypeptide composed of 26 amino acids. It is an amphoteric molecul e owing to the specific arrangement of amino acids, with nonpolar, hydrophobic and neutral amino acids at the end of the N-terminus, and hydrophilic and basic amino acids near the C-terminus. Research has showed that melittin incorporates into and disrupt the functions of natural and synthetic membranes by forming pores for ions, which eventually leads to disorder in the structure of phospholipid bilayers. (a) Explain how the molecular structure of the phospholipid allows for the formation of the phospholipid bilayer. ..…………………………………………………………………………...………………………………. ………………………………………………………………………...…………………………………... ……………………………………………………………………...……………………………………... …………………………………………………………………...………………………………………... ………………………………………………………………...……………………….……….………[2] (b) Explain why ions can only cross the membrane via the pores formed by melittin. ..…………………………………………………………………………...………………………………. ………………………………………………………………………...…………………………………... ..…………………………………………………………………………...………………………………. ..…………………………………………………………………………...………………………………. ……………………………………………………………………...……………………………………... …………………………………………………………………...………………………………………... ………………………………………………………………...……………………….……….………[3] (c) Suggest a possible disadvantage in using melittin as an anti-cancer drug. …………………………………………………………………...………………………………………... ………………………………………………………………...……………………….……….………[1]

7 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations (d) Explain, using honey bee as an example, how an aspect of the natural environment may affect phenotype. ..…………………………………………………………………………...………………………………. ………………………………………………………………………...…………………………………... ………………………………………………………………………...…………………………………... ………………………………………………………………………...…………………………………... ………………………………………………………………………...…………………………………... ..…………………………………………………………………………...………………………………. ..…………………………………………………………………………...………………………………. ……………………………………………………………………...……………………………………... …………………………………………………………………...………………………………………... ………………………………………………………………...……………………….……….………[4] [Total: 10]

8 St Andrew’s Junior College 2023 9744/02/Preliminary Examinations QUESTION 3 Carbon dioxide is present in the atmosphere at a concentration of around 0.04%. This level continues to rise as the result of human activities such as the clearing of rainforests and the burning of fossil fuels. It is often said to be the factor that affects the process of photosynthesis under normal conditions and is one of the limiting factors used to increase crop yield in glasshouses. A student investigated the effect of carbon dioxide on the rate of photosynthesis, using leaf discs cut from the leaf of a spinach plant and sodium hydrogencarbonate solution. Fig. 3.1 shows the method used by the student for his study. In this study, the student recorded the time taken for the leaf discs to rise to the surface. Fig. 3.1 (a) Explain the term limiting factor. ..…………………………………………………………………………...………………………………. ……………………………………………………………………...……………………………………... …………………………………………………………………...………………………………………... ………………………………………………………………...……………………….……….………[2] (b)