RVHS 2023 JC2 H2 Prelim P2 QP

RIVER VALLEY HIGH SCHOOL JC 2 PRELIMINARY EXAMINATION CANDIDATE NAME CENTRE NUMBER S CLASS 22J INDEX NUMBER BIOLOGY 9744/02 Paper 2 Structured Questions 13 September 2023 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your Centre number, index number and name 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. DO NOT WRITE ON ANY BARCODES. Answer all questions in the spaces provided on the Q uestion 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 not use appropriate units. 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 28 printed pages.

2 River Valley High School 2023 JC2 Preliminary Examination H2 Biology 9744/02 Answer all questions. 1 Collagen is the dominant protein in extracellular tissues such as bone, skin, and other connective tissues. (a) (i) Name the most common tripeptide repeat in tropocollagen. [1] (ii) Explain the significance of the most common amino acid in the tripeptide repeat. [2] (iii) Compare between the hydrogen bonds with in tropocollagen and with in an alpha helix of a protein. [3]

3 River Valley High School 2023 JC2 Preliminary Examination H2 Biology 9744/02 Fig 1.1 shows (a) diagrams of young and aged epidermal skin tissue and (b) the scanning electron micrographs of collagen fibrils under the epidermal layer of young and aged skin. young skin aged skin (a) (b) Fig. 1.1 (b) (i) Describe how collagen fibres are formed from tropocollagen. [2] (ii) With reference to Fig. 1.1, explain how changes in collagen affect the skin as a person ages. [2] [Total: 10] epidermal layer under epidermal layer

4 River Valley High School 2023 JC2 Preliminary Examination H2 Biology 9744/02 2 (a) Describe the roles of membranes within a cell. [2] ATP synthesis is catalysed by the enzyme ATP synthase. The process involves the coupling of H+ ion movement through ATP synthase with the catalysis of ATP formation. Fig. 2.1 shows a diagram of ATP synthase in a mitochondrion. Fig. 2.1 inner membrane of mitochondrion β-subunits involved in catalysis of ADP & P i to ATP H+ H+ H+ H+ H+ H+ H+ H+ H+ H+

5 River Valley High School 2023 JC2 Preliminary Examination H2 Biology 9744/02 (b) Describe how H+