JPJC 2023 J2 H2 BI Prelim P3 ANS

9744 / 03 [Turn over NAME : CLASS : JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examinations 2023 BIOLOGY Higher 2 9744/03 18 September 2023 Paper 3 Long Structured and Free-response Questions 2 hours Candidates answer on the Question Paper. Additional Materials: Answer Booklet READ THESE INSTRUCTIONS FIRST Write your class 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. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question on the separate Answer Booklet provided. 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 Section B Total This document consists of 20 printed pages.

2 JPJC/JC2 H2 Biology/Prelim/2023 Section A Answer all the questions in this section. 1 Reindeer are semi-domesticated ruminants that have adapted to challenging environment characterised by long winters and marked annual fluctuations in daylight. Comparative genome analyses revealed several genes that may have promoted the adaptation of reindeer, such as those involved in vitamin D metabolism (POR ), circadian rhythm (GR1A1), and tolerance to cold-triggered pain (SCN11A1). (a) A study was carried out to examine the gene involved in vitamin D metabolism ( POR) and the POR enzyme, which is an important enzyme in the vitamin D metabolic pathway. Vitamin D is made in the skin under the influence of UV light and is important in promoting calcium absorption and the mineralisation of bone for the rapid and robust growth of the antlers, which are important for various aspects of reindeer behaviour and reproductive success. Samples were taken from the reindeer, as well as roe deer and goats to examine for POR enzyme activity in a reconstituted system consisting of the enzyme and substrate. Fig. 1.1 With reference to Fig. 1.1, suggest how reindeer are able to produce sufficient vitamin D for their antler growth despite long winters with low amount of sunlight. ..................................................................................................................................... [2] 1. Reindeer has high enzyme activity of 32 arbitrary units, (25 a.u. more than roe deer, 30 a.u. more than goat) ; 2. Idea of reindeer has evolved / adapted + (a) efficient vitamin D metabolism pathway / (b) enzymes with high catalytic activity to maximise (OWTTE) the amount of vitamin D produced / (c) pr ocure/obtain high (OWTTE) levels of vitamin D with low levels of sunlight ;

3 JPJC/JC2 H2 Biology/Prelim/2