2026 VJC H2 Biology Prelim P2 QP

1 VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2026 HIGHER 2 NAME : ……………………………………………………….………………. CT CLASS: ………………...……… BIOLOGY Paper 2 Structured Questions 9477 / 02 18/09/2026 2 hours 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. 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 Total This document consists of 28 printed pages. [Turn over]

2 Answer all questions. 1 Catalase is a ubiquitous enzyme found in nearly all living organisms that are exposed to oxygen. It catalyses the decomposition of hydrogen peroxide (H2O2) into water and oxygen. Fig. 1.1 shows the results of an investigation into the effect of pH on the initial rate of reaction of catalase. Fig. 1.1 (a) With reference to the structure of enzymes, explain the shape of the curve in Fig. 1.1. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [2]

3 (b) Table 1.1 shows the effect of increasing substrate concentration on the initial rate of reaction of a fixed concentration of catalase at its optimum pH and temperature. Table 1.1 substrate concentration (H2O2 / mmoldm-3) initial rate of reaction (O₂ produced / cm3s⁻¹) 0.5 0.5 1.0 1.0 2.0 2.0 5.0 4.0 10.0 5.0 20.0 5.0 (i) Account for the relationship between substrate concentration and the initial rate of reaction. ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………..…… [3] (ii) A student hypothesised that the addition of a heavy metal ion, such as lead ( Pb2+), would decrease the initial rate of reaction of catalase at all substrate concentrations. Describe how the student could modify the investigation in Table 1.1 to test this hypothesis. ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………………... ………………………………………………………………………………………..…… [3] [Total: 8]

4 2 Lipids have a variety of important functions in cells. Phospholipids are major components of cell surface membranes, while triglycerides are stored in lipid droplets as an energy reserve. The structure and properties of lipids influence membrane structure, membrane function and the movement of substances across cell surface membranes. (a) Linoleic acid is an example of fatty acid found in some phospholipids. Phospholipids are major components of the cell surface membrane. Fig. 2.1 shows a molecule of linoleic acid. Fig. 2.1 At the start of the cold season, the proportion of phospholipids containing linoleic acid in the cell surface membranes of chickpea, Cicer arietinum , increases. Plants that do not make this change are less likely to survive at low temperatures. Explain how an increase in the proportion of phospholipids containing linoleic acid helps chickpea cells survive at low temperatures. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [3]

5 (b) Hepatocytes (liver cells) are involved in lipid metabolism and store triglycerides in lipid droplets. Fig. 2.2 is a diagram of a hepatocyte. Fig. 2.2 The triglycerides stored in a lipid droplet are surrounded by a single layer (monolayer) of phospholipids. Explain why phospholipids, rather than triglycerides, are used for the outer monolayer of the lipid droplet. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [3]

6 (c) Carbon dioxide (CO₂) is transported across the cell surface membrane of hepatocytes by a different mechanism from glucose. Name the transport mechanism for CO₂ and glucose and explain why these substances are transported across the membrane by different mechanisms. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [3] [9 marks]

7 3 Gentamicin is an antibiotic used to treat severe bacterial infections in children. Some children have a mutation in the MT-RNR1 gene. If gentamicin is given to children with this genetic mutation, it can cause deafness. Before gentamicin can be given to a child with a severe bacterial infection, polymerase chain reaction (PCR) and electrophoresis are used to test whether the child has this mutation. If the mutation is found, a different antibiotic must be given. (a) Describe and explain the role of Taq polymerase in PCR. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [2] (b) Taq polymerase synthesises new DNA strands during PCR. Explain how the antiparallel arrangement of DNA determines how new DNA strands are synthesised. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [2]

8 (c) PCR with primers specific to the MT -RNR1 gene is used to amplify DNA from the child that is being tested. The primers are designed so that the amplified product of the normal allele of MT-RNR1 is longer than the amplified product of the mutant allele. Gel electrophoresis is used to separate the PCR products. Fig. 3.1 shows the results of gel electrophoresis after using this method of PCR on DNA samples collected from three children. Fig. 3.1 State which of the children in Fig. 3.1 cannot receive the antibiotic gentamicin to treat a severe bacterial infection. ………………………………………………………………………………………………..… [1]

9 (d) Explain how gel electrophoresis produces the pattern of results shown in Fig. 3.1 from the PCR products of the MT-RNR1 gene. ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ……………………………………………………………………………………………………... ………………………………………………………………………………………………..… [4]