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

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Preliminary Examination Paper 3 / MS 1 HWA CHONG INSTITUTION (COLLEGE SECTION) 2023 JC2 9744 H2 BIOLOGY PRELIMINARY EXAMINATIONS PAPER 3 MARK SCHEME QUESTION 1 (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] any location where there is an overlap in range between subspecies BGS and WS (ii) Explain how this ice sheet affected the evolution of R. tarandus to result in the two different subspecies. [3] 1 ref. to geographical isolation 2 ref. to no gene flow between populations 3 ref. to adaptation to environment (b) Assess the relative importance of natural selection and genetic drift in producing the different body sizes of the two subspecies of reindeer. [2] 1 genetic drift is more important 2 ref. to any valid justification (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] 1 ref. to hybrid populations with more genetic variation 2 ref. to hybrid populations with more potential to adapt to climate change (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] 1 ref. to subspecies BGS having low index of seasonal range overlap 2 ref. to subspecies WS having high index of seasonal range overlap 3 ref. to link between index of seasonal range overlap and migratory / non-migratory behaviour (e) Outline how molecular techniques could be used to test the hypothesis that migratory behaviour in reindeer has a genetic basis. [3] 1 ref. to obtaining DNA 2 ref. to testing both subspecies BGS and WS 3 ref. to use relevant molecular techniques e.g. gel electrophoresis / DNA fingerprinting and compare results to see genetic differences

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Preliminary Examination Paper 3 / MS 1 (f) Discuss the importance of the trends observed in Fig. 1.4 for long-distance migratory animals. [4] 1 ref. to energy expenditure inv