2024 VJC H2 Bio P2 QP

1 VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2024 HIGHER 2 NAME : ……………………………………………………….………………. CT CLASS: ………………...……… BIOLOGY Paper 2 Structured Questions 9744 / 02 11/09/2024 2 hour Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name and CT class in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. 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 your working or if you do not use appropriate units. The number of marks is given in bracket [ ] at the end of each question or part question. Question Marks 1 2 3 4 5 6 7 8 9 10 11 Total This document consists of 31 printed pages. [Turn over]

2 Answer all questions. 1 Amoeba is a single-celled organism of the kingdom Protista. Am oeba gets its nutrients in a heterotrophic manner, taking in food from its surroundings. Fig. 1.1 shows the electron micrograph of an amoeba. Fig. 1.1 (a) With reference to Fig. 1.1 and the information provided, (i) identify structure X and Y and state a structural difference between them. …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... ……………………………………………………………………………………………..… [2]

3 (ii) explain the importance of structure X to the amoeba. …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... ……………………………………………………………………………………………..… [3] (b) Marseillevirus is a virus that infects amoeba. It is taken up by amoeba via phagocytosis. Upon membrane fusion, new progeny viruses are formed through DN A replication and protein synthesis. The progeny viruses are then released as the amoeba is lysed. Fig. 1.2 shows the structure of Marseillevirus. Fig. 1.2 With reference to Fig. 1.2 and the information provided, explai n how Marseillevirus challenges the cell theory. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [3] [Total: 8]

4 2 Some structural features of phospholipids are listed in Table 2.1. Table 2.1 features affect role in cell surface membrane synthesised by condensation hydrophobic fatty acid chains unsaturated fatty acid chains saturated fatty acid chains (a) (i) Indicate, with the use of a tick (√), which of the structural features in Table 2.1 affect the role of phospholipids in the cell surface membrane. [1] (ii) Outline how a property of phospholipids allows them to form an effective barrier as the cell surface membrane. …………………………………………………………………………………………………... ……………………………………………………………………………………………..… [1] (b) Many multicellular organisms produce antimicrobial polypeptide s (APs) that protect them against prokaryotes. Fig. 2.1 shows one type of AP that acts on the cell surface membrane of prokaryotes. Fig. 2.1

5 Fig. 2.2 shows further information about a channel formed in th e cell surface membrane by the APs. Fig. 2.2 Using Fig. 2.2, calculate the cross-sectional area of the chann el through which ions can pass. Use π = 3.14 in your calculation. Give your answer in nm 2 and to 1 decimal place. cross-sectional area of the channel = ……………………………… [2] (c) Prokaryotic membranes do not contain cholesterol. APs damage prokaryotic cells but do not damage eukaryotic cells in the organisms that produce them. Explain how that is possible. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [2]

6 (d) To observe the action of APs on prokaryotes, scientists made u se of a microscope that detects fluorescence, as well as monoclonal antibodies. Suggest how the action of APs on prokaryotes can be observed. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [2] [Total: 8]

7 3 Collagen is the most abundant protein found in the human body. Glycine is a common amino acid found in collagen and plays an important role in contributing to the high tensile strength of collagen. (a) Explain how glycine contributes to the high tensile strength o f collagen. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [3] (b) In the human skin, the enzyme collagenase is synthesised and s ecreted by the fibroblast cells to break down collagen in damaged tissues and help in the growth of healthy tissues. Describe one structural difference between collagenase and collagen and exp lain the significance of this difference to the function of the respective proteins. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [3]

8 (c) Collagenase has an optimal pH around pH 7. The pH of the extracellular matrix and tissue microenvironment can influence collagenase activity and collagen turnover. For example, inflammation or infection can alter the local pH and impact collagen degradation processes. Explain how alterations in pH can affect the activity of collagenase. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [3] (d) Under natural conditions, healthy skin tissues grow under stri ct regulation. Explain why this is significant. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [2] [Total: 11]

9 4 Fig. 4.1 shows an electron micrograph of protein synthesis in a eukaryotic cell. Fig. 4.1 (a) (i) Identify structure X and Y and describe two structural differences between them. …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... ……………………………………………………………………………………………..… [3] (ii) Arrow Z points to the end of a molecule. State the directionality of the end of th