MI 2023 J2 H2 BI Prelim P2 QP

Class Adm No Candidate Name: ___________________________________ This question paper consists of 28 printed pages, including 2 blank pages. [Turn over] 2023 End-of-Year Examination Pre-University 3 H2 Biology 9744/02 Paper 2 Structured Questions 12 September 2023 2 hours READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your Admission number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions in the question booklet. 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. At the end of the examination, fasten all your work securely together. For Examiner's Use 1 /10 2 /9 3 /10 4 /12 5 /10 6 /13 7 /11 8 /12 9 /5 10 /8 Total /100

2 9744/02/PU3 EOY/2023 Answer all questions. 1. Biomolecules function as building blocks for macromolecules to be assembled. Carbohydrate is made up of many monosaccharides and can be found in both animals and plants. (a) Name the bond formed between monomers in cellulose. ……………………………………………………………………………………………… [1] (b) Illustrate with a labelled diagram how two monomers form the bond in (a) in cellulose. Circle the bond formed between the two monomers. Fig. 1.1 shows the partial structure of the monomer. Fig. 1.1 [4]

3 9744/02/PU3 EOY/2023 [Turn Over] (c) One of the defining features of all cells is the cell surface membrane. This membrane is composed of phospholipid bilayer, with other biomolecules dispersed throughout the bilayer. (i) Describe the roles of carbohydrates in the cell surface membrane. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………….. [2] (ii) During the synthesis of phospholipid, the phospholipid sometimes needs to be moved between the layers. The movement is facilitated by a transmembrane protein called floppase. Fig.1.2 shows floppase moving a phospholipid from the inner layer to the outer layer of the cell surface membrane. Fig. 1.2 Due to their hydrophilic heads, phospholipid molecules cannot cross the hydrophobic region of the membrane from the inner layer to the outer layer without floppase. Using your knowledge of proteins, suggest how the structure of floppase allows phospholipids to cross the hydrophobic region of the membrane. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………… [3] [To