DHS 2022 Y5 H2 Promo Paper 2 (QP)

© DHS 2022 9744/02 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Promotional Examination Year 5 H2 BIOLOGY 9744/02 Paper 2 Section A (Structured Questions) 27 September 2022 Paper 2 Section B (Long Structured and Free-Response Questions) 1 hour 30 minutes READ THESE INSTRUCTIONS FIRST: Write your class, index number and name 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. Sections A and B 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 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 Paper 1 MCQ 15 Paper 2 Section A 1 6 2 10 3 9 4 10 Section B 1 15 2 15 Total 80 This document consists of 15 printed pages and 3 blank pages.

2 © DHS 2022 9744/02 Section A: Structured Questions Answer all questions. Question 1 Fig 1 shows a part of the collagen synthesis pathway at the rough endoplasmic reticulum. Fig 1 With reference to Fig 1, (a) (i) name the most common amino acid in procollagen chain, [1] (ii) name the bond that stabilises the procollagen trimer, [1] (b) describe how collagen fibrils are synthesized outside the cell from procollagen trimers. [4] Total: [6]

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4 © DHS 2022 9744/02 Question 2 Polygalacturonase (PG) plays an important role in fruit softening by making the pectin of the cell wall more soluble. In order to slow down the ripening of tomatoes, antisense RNA technology was used where a second copy of the gene was inserted into the tomato genome in the antisense direction (transformed fruit). PG antisense RNA has a sequence which is complementary to PG mRNA. When the gene coding for antisense RNA is expressed, it interferes with the production of the PG, delaying the ripening process. mRNA extracted from ripe and unripe untransformed and transformed fruits were hybridised to radioactively labelled pr obes specific to the PG sense strand. Fig 2 shows the results expressed as the percentage of PG mRNA in ripe untransformed fruit. Fig 2 100 90 80 70 60 50 40 30 20 10 0

5 © DHS 2022 9744/02 [Turn over (a) Contrast the process of the synthesis of PG mRNA and the synthesis of PG in a cell. [4] (b) Explain how the antisense RNA techno