HCI 2023 JC2 9744 H2 Bio Prelim P3 QP (Sharing)

© Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 22S7__ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 3 Long Structured Questions and Free-response Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/03 13 September 2023 2 hours INSTRUCTIONS TO CANDIDATES There are four question booklets (I - IV) to this paper. Write your name, CT group, Centre number and index number in the spaces provided at the top of this cover page and on the lines provided at the top of the cover pages of Booklets II, III and IV. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in the spaces provided on the Question Paper. INFORMATION FOR CANDIDATES 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. You are reminded of the need for good English and clear presentation in your answer. This document consists of 21 printed pages and 1 blank page. For Examiners' Use Section A 1 / 30 2 / 10 3 / 10 Section B 4 or 5 / 25 Final Mark

2 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 SECTION A Answer all the questions in this section. QUESTION 1 Migratory behaviour is commonly defined as the movement from one location to another and back, allowing animals to exploit seasonally - and geographically-variable resources or avoid unfavo urable conditions. Migratory animals are significantly threatened by the effects of habitat fragmentation and habitat loss. In the case of terrestrial mammals, this results in nearly a quarter of species being at risk of extinction. The reindeer is one such example. In populations of reindeer, the proportion of individuals considered as “migrants” can vary dramatically. There is therefore a possibility that, under the condition that migratory behavior is genetically determined, those individuals or populations that are migratory will be further impacted by humans, and this impact could result in the permanent loss of the migratory trait in some populations. Two subspecies of reindeer, Rangifer tarandus , can be found in North America. Members of the different subspecies belong to the same species but have some morphological d ifferences and are found in different geographical locations. Fig. 1.1 shows a reindeer. Fig. 1.1 Table 1.1 compares the features of the two North American reindeer subspecies. Table 1.1 feature Woodland subspecies, R. tarandus caribou (WS) Barren Ground subspecies, R. tarandus groenlandicus (BGS) habitat southern woodland (warmer) northern tundra (colder) type of food tree leaves, grass lichens, moss summer and winter feeding grounds overlap yes no carry out long migrations no yes body size large small colour of fur dark light

3 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 Fig. 1.2 shows a map of the present day western North America. The locations of sampled reindeer populations are represented by black numbered circles. Such populations are referred to as “herds” as they might not be genetically or ecologically distinct. In Fig. 1.2, the grey-scale polygons show the distribution of the two subspecies in which • diagonal black lines represent the Barren Ground subspecies, R. tarandus groenlandicus (BGS) • horizontal lines, light gray, and black represent Northern Mountain, Bor eal and Central Mountain Woodland subspecies, R. tarandus caribou (WS). Fig. 1.2 (a) During the last ice age, an ice sheet separated southern and northern populations of R. tarandus in North America. (i) Indicate on Fig. 1.2 with an “X” a possible location of the ice sheet formed during the last ice age. [1]

4 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (ii) Explain how this ice sheet affected the evolution of R. tarandus to result in the two different subspecies. [3] (b) Assess the relative importance of natural selection and genetic drift in producing the different body sizes of the two subspecies of reindeer. [2] (c) Interbreeding has occurred between individuals of the two subspecies which now live in the area previously covered by the ice sheet. Comment on how the hybrid populations compare to the pure subspecies in terms of genetic variation and potential to adapt to climate change. [2]

5 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 Scientists have assessed the seasonal migratory behaviours of the two subspecies BGS and WS. Fig. 1.3 shows the number of individuals in subspecies BGS and WS with varying degrees of seasonal ranges overlap, where the index ranges from 0.0 (no overlap) to 1.0 (fully overlap). The index of seasonal range overlap is between winter and summer ranges frequented by individual reindeers. Fig. 1.3 (d) Table 1.1 in page 2 suggests that the subspecies WS is mainly non-migratory whereas subspecies BGS is primarily migratory. Explain how the data shown in Fig. 1.3 supports the above suggestion. [3] Barren Ground Northern Mountain Boreal Number of individuals Overlap between seasonal ranges

6 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (e) Outline how molecular techniques could be used to test the hypothesis that migratory behaviour in reindeer has a genetic basis. [3] Researchers have detected more than 50 single nucleotide polymorphisms (SNPs) associated with migratory behaviour, which are in genes with hypothesized roles in determining migration in other organisms. One of the strongest SNP associated with migratory behaviour was detected in the gene UBE3D which controls the metabolism of fat in migratory animals. Fig. 1.4 shows the generalized relationship between rate of energy expenditure expressed as multiples of basal metabolic rate (BMR) and duration of activity in animals. Long-distance migratory animals clearly lie outside of the stereotypical pattern because very high rates of energy expenditure are maintained for exceptionally long periods without feeding. Such animals are expected to have higher aerobic capacity and longer endurance. Fig. 1.4

7 © Hwa Chong Institution 2023 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (f) Discuss the importance of the trends observed in Fig. 1.4 for long-distance migratory animals. [4] Research has shown that migratory animals alter their energy intake as well as their dietary composition and food preferences for higher amounts of fats in preparation for migration. Fatty acids contain gr eater energy yield per unit mass than carbohydrates, making stored fat the most efficient fuel. The energy yield from fatty acid oxidation is high. For example, oxidation of a molecule of fatty acid derivative 16-carbon palmitoyl CoA to carbon dioxide and water produces: • 8 acetyl CoA, where each acetyl CoA subsequently produces 12 ATP upon complete oxidation • 7 NADH • 7 FADH2. However, activation of the fatty acid requires two ATP molecules. (g)(i) C alculate the net number of ATP molecules produced from the complete oxidation of one molecule of 16-carbon palmitoyl CoA. Show your working clearly in the space provid