2026 NYJC H2 Biology Prelim Paper 2 QP

9477 / H2 Biology / 02 NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS BIOLOGY 9477/02 Paper 2 Structured Questions 16 September 2026 Candidates answer on the Question Paper. No Additional Materials are required. 2 hours READ THESE INSTRUCTIONS FIRST Write your name and CT on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do no use staples, paper clips, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. 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 no use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 2 3 4 5 6 7 8 9 10 11 Total This document consists of 25 printed pages and 3 blank pages. [Turn over

9477 / H2 Biology / 02 2 Answer all the questions in this section. 1 Fig. 1.1 is a diagram of the cell surface membrane of a squamous epithelial cell lining an alveolus. Fig. 1.1 (a) A student measured the line A – B and calculated the actual width of the membrane in Fig. 1.1. (i) State the unit that the student should use for the actual width of the membrane. [1]

9477 / H2 Biology / 02 3 (ii) With reference to Fig. 1.1, state how to identify the external surface of the cell surface membrane. [1] (b) Name R and S in Fig. 1.1 and describe their roles in the membrane. component R: name role component S name role [4] (c) The inner and outer membranes of the mitochondrion differ in the detail of their membrane components. The inner membrane is also much less permeable than the outer membrane. Suggest one way in which the structure of the inner membrane may differ from that of the outer membrane to produce a less permeable inner membrane. [1] [Total: 7]

9477 / H2 Biology / 02 4 2 (a) The lock‑and‑key hypothesis and the induced‑fit hypothesis are used to describe the interaction of enzymes and their substrates. Compare between the lock‑and‑key hypothesis and the induced‑fit hypothesis. [2] (b) Phosphorylase enzymes can catalyse the synthesis of starch and the breakdown of starch in some plant tissues. A reaction catalysed by starch phosphorylase is shown in Fig. 2.1. Fig. 2.1 (i) Name the specific bond formed when the linear chain of starch is extended. [1] (ii) Starch consists of two distinct polysaccharides, amylose and amylopectin. Explain why amylopectin allows for faster rate of glucose release by phosphorylase enzymes compared to amylose. [2]

9477 / H2 Biology / 02 5 A student carried out an experiment to study the synthesis of starch by phosphorylase found in potato tissue. The student was provided with a solution, E, extracted from potato tissue. The extract was filtered to remove all starch grains. Extract E contained biological molecules from the potato tissue, including phosphorylase but no starch. Iodine solution was used to confirm that starch was not present in extract E. Iodine solution turns from yellow to blue-black in the presence of starch. The student then added a small drop of a dilute starch solution and a solution of glucose 1‑phosphate to a test‑tube containing extract E. Samples of the reaction mixture in the test‑tube were removed every minute and a drop of iodine solution was added to each. The student used a colou rimeter to measure the absorbance of the solution in each sample. The results are shown in Fig. 2.2.

9477 / H2 Biology / 02 6 Fig. 2.2 (iii) Explain the results shown in Fig. 2.2. [2] (iv) After 12 minutes, the student added a solution containing phosphate ions to the reaction mixture. The student continued taking samples every minute, adding iodine solution to each sample. The absorbance of the solution in each of these samples was measured. The results showed that the absorbance decreased over time. Suggest why the absorbance decreased. [1]

9477 / H2 Biology / 02 7 (c) Muscle cells contain glycogen phosphorylase. Fig. 2.3 shows the effect of caffeine on the activity of glycogen phosphorylase at different concentrations of substrate. Fig. 2.3 A student concluded that caffeine acts as a non‑ competitive inhibitor of glycogen phosphorylase. Explain how the results in Fig. 2.3 support this conclusion. [2] [Total: 10]

9477 / H2 Biology / 02 8 3 In 2008, a woman had her damaged left bronchus replaced by one constructed using her own stem cells. A section of the trachea from a donor was treated in order to remove the cells of the donor, leaving only a framework of collagen. Adult stem cells derived from the woman’s own bone marrow were then added to this collagen framework. Samples of these stem cells, together with cells derived from the lining of her trachea, were placed in a bioreactor for four days during which time they multiplied to coat the collagen framework. This was used to replace the damaged section of her bronchus. A month later the transplanted tissue had developed its own blood supply. This was claimed to be the first successful transplant using tissues derived from the patient’s own stem cells. (a) Suggest the advantages of using a patient’s own stem cells to treat a damaged bronchus as described in the passage, rather than transplanting a complete bronchus. [2] (b) Stem cells from human bone marrow that are involved in blood cell formation are described as multipotent, rather than totipotent. Describe how multipotent stem cells differ from totipotent stem cells. [2] (c) Name a type of cell which may form from bone marrow stem cells. [1] [Total: 5]

9477 / H2 Biology / 02 9 4 In an experiment, chromatin was isolated from developing red blood cells and pancreatic cells from rats. The chromatin was treated with DNase I, an enzyme that digests exposed DNA but cannot easily digest DNA tightly associated with histones. After treatment, the remaining DNA that was not digested was extracted. Southern Blotting was performed on these DNA, using radioactive labelled DNA probes specific to the particular genes. The percentage binding of radioactively -labelled DNA probes to the se remaining undigested DNA were measured. Some of the results are shown in Table 4.1 below. Table 4.1 Sample Source of chromatin Gene radioactive DNA probe is specific to Percentage binding of radioactive DNA probe 1 Developing red blood cells (nucleated) α-globin gene 25 2 Pancreas α-globin gene 91 3 Developing red blood cells (nucleated) Chymotrypsin gene 93 (a) Explain how DNA in the chromatin are protected from digestion by DNase I. [2] (b) With reference to Table 4.1, identify which gene is more actively transcribed in developing red blood cells and explain your answer. [3]

9477 / H2 Biology / 02 10 (c) When a red blood cell is fully mature, it loses its nucleus and becomes a denucleated cell. However, studies have shown that proteins are still being synthesised in red blood cells. These studies found that there is high level of transcription in developing red blood cells, which produces large numbers of mRNAs that are stored in the cytoplasm. These mRNAs are stable and remain functional in mature red blood cells for protein synthesis. (i) Describe the processes that occur in the nucleus of the developing red blood cells that result in the stability of the mRNAs. [