2026 RI H2 Biology Prelims P1 Questions

© RI 2026 Preliminary Examinations 9477/01 [Turn over RAFFLES INSTITUTION 2026 Year 6 Preliminary Examination Higher 2 BIOLOGY 9477/01 Paper 1 Multiple Choice 25th September 2026 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name and shade your Index Number on the OMR Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions in this paper. Answer all questions. For each question there are four possible answers A, B, C, and D. Choose the one you consider correct and record your choice in soft pencil on the separate OMR Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. Calculators may be used. (Erase all mistakes completely. Do not bend or fold the OMR Answer Sheet). This document consists of 25 printed pages. Raffles Institution Internal Examination

2 © RI 2026 Preliminary Examinations 9477/01 1. A polymer Q was extracted from the oyster mushroom Pleurotus ostreatus. Its monomer was found to be a modified glucose molecule, with one OH group replaced by an NHCOCH3 group that is represented by N(Ac) in the diagram below. The diagram shows both the polymer and the structure of its monomer. Which of the following statements below correctly describes Q? A Its monomers will give a negative result when tested with Benedict’s reagent. B Before modification, its monomer is a monomer of amylopectin. C Q has a structure similar to glycogen. D Many interchain hydrogen bonds can form between Q molecules. monomer polymer

3 © RI 2026 Preliminary Examinations 9477/01 [Turn over 2. β-galactosidase enzyme can digest both lactose and O -nitrophenyl-β-D-galactopyranoside (ONPG). ONPG is structurally similar to lactose and is colourless. After hydrolysis by β - galactosidase enzyme, the products of the digestion of ONPG are yellow and can be detected by a spectrophotometer. A stock solution is made by mixing lactose and ONPG in a 1:1 ratio, and labelled “lac-ONPG”. It is then proportionately diluted to different concentrations. 1 cm3 of 5% β-galactosidase enzyme is added in all experiments. The effects of three different concentrations of galactose on the reaction rate are studied, and the results are shown in the graph below. From the above, how many statement(s) below can be inferred? • Galactose competes with both lactose and ONPG for the active site of the β- galactosidase enzyme. • The yellow colour standard is achieved earlier with 1 lactose: 4 ONPG mixture ratio compared to 1 lactose : 1 ONPG mixture ratio. • Galactose likely inhibits β-galactosidase enzyme. • Adding another monosaccharide like glucose will also result in inhibition. A 1 B 2 C 3 D 4 rate at which a certain yellow colour standard is achieved/ arbitrary units 0 mM galactose 5 mM galactose 10 mM galactose concentration of lac-ONPG / %

4 © RI 2026 Preliminary Examinations 9477/01 3. Based on the diagram below, which of the following is /are valid conclusion(s) regarding the involvement of the signal recognition particle (SRP) in the formation of a secretory protein. 1 The SRP binds to the end of the polypeptide which contains the C-terminus. 2 The SRP is complementary in shape to the active site on the SRP receptor. 3 70S ribosomes can be attached to the translocation complex of endoplasmic reticulum. 4 The polypeptide is too large to pass through the transient pores of the phospholipid bilayer. A 1, 2 and 3 B 1 and 3 C 2 and 4 D 4 only cytosol lumen of endoplasmic reticulum SRP SRP receptor polypeptide mRNA translocation complex

5 © RI 2026 Preliminary Examinations 9477/01 [Turn over 4. A group of students did some research on membranes obtained from bull frogs. M embrane proteins were labelled with fluorescent dye and these were their observations: 1 When a small region of the membrane was bleached using a fluorescent dye, it was observed that the region loses fluorescence over time. 2 Receptors labelled with fluorescent dye change position within the plane of the membrane over time but show limited long-range diffusion. 3 Lectins are proteins that bind to polysaccharides. They only attach to the outside of membrane samples. 4 Electron microscope images of membranes fractured by freezing show a large number closely arranged small particles interrupted by larger particles. 5 Bull frog tadpole membranes contain more cholesterol and less unsaturated fatty acid chains than adult frog membranes. 6 Some proteins can only be separated from the membrane by disrupting the membrane with detergent. Which observations support our currently accepted model of the cell surface membrane? A 1, 2 and 4 only B 1, 3 and 6 only C 2, 4 and 5 only D 3, 5 and 6 only

6 © RI 2026 Preliminary Examinations 9477/01 5. The transmission electron micrograph below shows a cell in a stage of the mitotic cell cycle. Which statement explains why the stage of the mitotic cell cycle shown in the diagram above is difficult to identify? A The chromosomes have supercoiled and are visible, but centrioles are not visible, hence unclear if it is prophase. B Anaphase may be continuing, or telophase may be starting. C It is unclear whether the electron micrograph shows two cells in metaphase. D The cells appear to be in interphase as DNA is replicating.

7 © RI 2026 Preliminary Examinations 9477/01 [Turn over 6. A species of beetle has a diploid chromosome number of 2n = 10. Researchers exposed female beetles to Compound X, a chemical suspected to interfere with chromosome behaviour during meiosis. Treated females were crossed with untreated males. The chromosome number of 100 offspring was analysed and shown in the table below. offspring chromosome number number of offspring 8 2 9 22 10 51 11 23 12 2 Researchers also examined meiotic cells from treated female beetles and obtained the following data. observation in meiotic cells percentage of cells/% homologous chromosomes fail to separate during anaphase I 41 sister chromatids fail to separate during anaphase II 6 abnormal spindle attachment at kinetochores 47 failure of DNA replication before meiosis 0 Which statement is most consistent with the data? A Compound X disrupts kinetochore-spindle attachment during meiosis I, resulting in non- disjunction of homologous chromosome, and resulting in production of n+1 and n- 1 gametes. B Compound X disrupts centromere cohesion during meiosis II, causing premature separation of sister chromatids and resulting in production of n+1 and n-1 gametes only. C Compound X increases crossover frequency near centromeres, producing recombinant chromosomes that are unequally distributed during anaphase I. D Compound X inhibits DNA replication during interphase, leading to chromosome damage and uneven distribution of chromosomes during gamete formation.

8 © RI 2026 Preliminary Examinations 9477/01 7. A culture of bacteria had all i