2026 EJC JC2 H2 Biology Prelims P2 (A)

©EJC 2026 9477/02/J2H2PRELIM/2026 [Turn over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examinations 2026 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME ANSWERS CIVICS GROUP 2 5 - REGISTRATION NUMBER H2 Biology Paper 2 Structured Questions 9477/02 02 September 2026 2 hours READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on all the work you hand in. Candidates are to answer: All questions on the Question Paper. Write your answers in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue, or correction fluid/tape. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 21 printed pages. For Examiner’s Use 1 / 6 2 / 9 3 / 7 4 / 10 5 / 10 6 / 10 7 / 8 8 / 8 9 / 10 10 / 7 11 / 5 Total 90

2 ©EJC 2026 9477/02/J2H2PRELIM/2026 Answer all questions. 1 Amylose and triglyceride are macromolecules. (a) Explain why amylose and triglyceride are macromolecules, but only amylose is a polymer. [2] 1. Both are large molecules (A: composed of many atoms) (I: composed of more than one molecule); 2. However, only amylose is made up of many α-glucose repeating units/monomers joined together by α-1,4 glycosidic bonds while triglyceride is made up of glycerol and fatty acids joined together by ester bonds, where glycerol and fatty acids are different components and not repeating units (OWTTE); 1 (b) 2 State the number of oxygen atoms in one molecule of triglyceride. [1] 3 4 6 (c) Contrast the structural features of amylose and the structural features of cellulose. [3] Feature Amylose Cellulose Monomer α-glucose β-glucose Bonds between monomers α-1,4 glycosidic bonds (R: α-1,6 glycosidic bonds) β-1,4 glycosidic bonds Orientation of monomers α -glucose molecules are in the same orientation when they join to each other Alternate / adjacent glucose residues inverted/rotated 180° with respect to one another Shape Amylose is coiled up into a compact helical shape Cellulose molecules are long, straight chains (I: linear) Bonds between chains / molecules No inter-chain hydrogen bonding in amylose hydroxyl groups projecting outwards in both directions allow intermolecular / inter-chain hydrogen bonding (leading to microfibril formation for cellulose) Microfibril formation No microfibril formation in amylose Cellulose molecules align together to form microfibrils [Total: 6]

3 ©EJC 2026 9477/02/J2H2PRELIM/2026 [Turn over 2 A student constructed a table to compare the structural features of a plant cell, a bacterial cell, and a virus. (a) Complete Table 2.1. Table 2.1 feature plant cell bacterial cell virus external structure cell wall composed of cellulose cell wall composed of peptidoglycan capsid composed of capsomeres size(s) of ribosomes 80S and 70S 70S no ribosomes genetic material DNA DNA DNA or RNA 1 mark per box [3] (b) The cholera bacterium, Vibrio cholerae, releases a toxin called choleragen. The toxin causes the loss of chloride ions and water from epithelial cells into the lumen of the intestine, causing severe watery diarrhoea. Fig. 2.1 shows the events that occur in cells lining the intestine when choleragen binds to the cell surface membrane of one of these epithelial cells. Fig. 2.1 (i) State the type of molecule that forms the receptor for choleragen. [1] Glycolipid (R: protein, glycoprotein) (ii) The process by which chloride ions leave the epithelial cell requires energy. State and describe this process. [3] 1. Active transport; 2. Cl– ions are pumped out of the epithelial cell against their concentration gradient (A: transported out by protein pumps) 3. Energy released from ATP hydrolysis is required (A: ATP is hydrolysed);

4 ©EJC 2026 9477/02/J2H2PRELIM/2026 (iii) Explain the movement of water molecules when choleragen is present. [2] 1. Accumulation of Cl– ions lowers the water potential of the intestinal lumen compared to epithelial cells; OR loss of Cl– ions from epithelial cells raises the water potential of the cytoplasm compared to the intestinal lumen; 2. Water leaves the epithelial cells / enter the lumen of intestine via osmosis; [Total: 9] 3 The lock-and-key hypothesis and the induced-fit hypothesis are used to describe the interaction of enzymes and their substrates. (a) Describe one similarity and one difference between the lock -and-key hypothesis and the induced-fit hypothesis. [2] Similarity • substrate(s) binds to enzyme active site • enzyme-substrate complex forms • product(s) leaves enzyme active site • enzyme can be re-used / enzyme remains unchanged after the reaction • enzyme active site specific to one or very similar substrate(s)      R: enzyme active site complementary in conformation and charge to substrate R: lower activation energy R: enzyme activity can be affected by temperature / pH / inhibition Difference • active site fully complementary in conformation and charge to substrate for lock-and- key hypothesis while active site not fully complementary in conformation and charge to substrate for induced fit hypothesis (R: not complementary) • no change in conformation of active site after substrate binds to active site for lock- and-key hypothesis while change in conformation of active site after substrate binds to active site for induced fit hypothesis (b) Fig. 3.1 summarises the reaction catalysed by lactase. Fig. 3.1 Draw the ring structure of α-glucose in the box provided to complete Fig. 3.1. [1]

5 ©EJC 2026 9477/02/J2H2PRELIM/2026 [Turn over All correct for one mark If decision is to leave out the H atoms, then this must be consistent for all C1 to C5 hydrogen atoms – leaving out only the C5 H atom is incorrect (zero marks) (c) The lactose in milk can be hydrolysed using immobilised lactase or free lactase ( lactase in solution). This results in milk and milk products that do not contain lactose and so are suitable for lactose-intolerant people. Scientists carried out an investigation to compare the activity of lactase immobilised in very small magnetic beads (magnetic microspheres) with free lactase, at different temperatures and at different pH values. Fig. 3.2 shows the activity of immobilised lactase and the activity of free lactase at 5 different temperatures. Fig. 3.3 shows the activity of immobilised lactase and the activity of free lactase at 8 different pH values. Fig. 3.2 Fig. 3.3 One advantage of using magnetic microspheres with immobilised lactase is that they can be easily recovered using an electric field and reused.

6 ©EJC 2026 9477/02/J2H2PRELIM/2026 With reference to Fig. 3.2 and Fig. 3.3, explain why the results indicate that there are other advantages in using immobilised lactase instead of free lactase to produce lactose -free products. [4] 1. percentage of maximum activity for immobilised lactase is higher from 38.5°C to 55°C (A: temperatures higher than 38.5°C) (R: 35-55°C) than that of free lactase; OR percentage of maximum activity for immobilised lactase decreases at slower rate from 100% at 35°C to 15% at 55°C than that of free lactase (from 100% at 35°C to 4% at 55°C); 2. percentage of maximum activity for immobilised lactase is higher from pH 5.5 to 9.0 except pH 6.5 to 7.0 (R: pH 5.5 to 9.0) than that of free lactase OR 17% activity for immobilised lactase higher than 0% activity for free lactase at pH 5.5 [e.g. of specific value] 3. immobilised lactase is more tolerant to temperature / pH fluctuations / changes (A: more thermostable at high temperatures) (A: