NJC 2023 H2 Biology Prelim P3 Ans

©NJC 2023 9744/03/SH2/H2/Biology/Preliminary Examination [Turn over NATIONAL JUNIOR COLLEGE, SINGAPORE Senior High 2 Preliminary Examination Higher 2 CANDIDATE NAME BIOLOGY CLASS 2bi2___ REGISTRATION NUMBER BIOLOGY Paper 3: Long Structured and Free-response Questions Candidates answer on the Question Paper and Answer Booklet No Additional Materials are required. 9744/03 25 August 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your name and Biology 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. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in the Answer Booklet. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your workings or if you do not use appropriate units. The number of marks is given in the brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 /30 2 /10 3 /10 Section B 4/5 /25 Total /75 This document consists of 14 printed pages and 2 blank pages.

2 ©NJC 2023 9744/03/SH2/H2/Biology/Preliminary Examination Section A Answer all the questions in this section. 1 FoxO1 is a protein found in pancreatic β cells. Fig.1.1 shows a model of FoxO1. Fig. 1.1 (a) Describe how monomers may be linked together to form the FoxO1 polypeptide chain. Peptide bonds formed between amino and carboxyl groups; Condensation reaction; Removal of water molecules; Make bottom border for writing. [2] (b) Explain how amino acids that are spaced far apart in the Fox O1 polypeptide chain may be brought together in its 3-dimensional structure. Stretches of amino acids in the polypeptide chain first adopt/fold/coil into a regular, recurring shape/repeating pattern [OR ref to localized folding of polypeptide backbone into secondary structures]; such as α-helix; [Beta sheet not seen in Figure] These secondary structures are stabilized by hydrogen bonds formed between the –C=O and –NH groups of the peptide bonds/backbone; The secondary structures extensively/further folds to form a specific three-dimensional globular structure, bringing amino acids that were spaced far apart in the linear chain to be close together in the tertiary structure; This tertiary structure is maintained by interactions between the R-groups of amino acids; Ref to hydrogen bonds, ionic bonds, disulphide bonds and hydrophobic interactions (At least 2);

3 ©NJC 2023 9744/03/SH2/H2/Biology/Preliminary Examination [Turn over [4] Diabetes is often associated with the failure of the β (beta) cells in the pancreas, but it is unclear what actually causes this failure. Some studies have suggested that this failure