2024 JPJC Prelim Biology P3 (Q)

9744 / 03 [Turn over NAME : CLASS : JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examination 2024 BIOLOGY Higher 2 9744/03 11 September 2024 Paper 3 Long Structured and Free-response Questions 2 hours 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/2024 Section A Answer all questions in this section. 1 Mammoths are extinct mammals related to elephants. About three million years ago, the ancestors of mammoths migrated from Africa into Europe and Asia. There, about 1.7 million years ago, the steppe mammoth evolved and became adapted to the cooler conditions. Then, about 700 000 years ago, as the climate changed and the Arctic became much colder, the woolly mammoth evolved. Characterised by its long, curved tusks, woolly mammoths showed several obvious adaptations to reduce heat loss, including thick fur, small ears and small tails. Fig. 1.1 shows a drawing of a woolly mammoth. Fig. 1.1 (a) (i) Outline the sources of genetic variation which drives microevolution in a population. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ................................................................................................................... [2]

3 JPJC/JC2 H2 Biology/Prelim/2024 [Turn over (ii) Account how natural selection may have brought about the evolution of the woolly mammoth from the steppe mammoth. ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ................................................................................................................... [4] (b) A frozen, 43 000 years old woolly mammoth was found in Siberia. Its DNA was extracted and sequenced. Bioinformatics was used to compare the sequences of the genes coding for the α and β chains of haemoglobin of woolly mammoths, modern Asian elephants and humans. Explain why bioinformatics was used to compare these gene sequences and suggest a conclusion that could be made from the percentage similarity data obtained. ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ............................................................................................................................ [2]

4 JPJC/JC2 H2 Biology/Prelim/2024 (c) In addition to DNA sequencing, Southern blotting followed by nucleic acid hybridisation can be used to analyse the genes for the α and β chains of haemoglobin in both woolly mammoth and the modern Asian elephants. To visualise the results, autoradiography is carried out at the end. The im ages formed on the photographic X-ray film would correspond to the bands that contain the genes for the α and β chains of haemoglobin. Outline the process of Southern blotting and nucleic acid hybridisation. ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ............................................................................................................................ [4]

5 JPJC/JC2 H2 Biology/Prelim/2024 [Turn over Question 1 continues on page 6.

6 JPJC/JC2 H2 Biology/Prelim/2024 (d) Fig. 1.2 shows the amino acid residue differences among the α and β chains of haemoglobin in human (Hb A), Asian elephant (rHb AE), and woolly mammoth (rHb WM). Each amino acid residue is represented by a different letter of the alphabet. The differences between rHb AE and rHb WM compared to the Hb A sequence are shown. An asterisk (*) denotes the differences in amino acid between rHb WM and rHb AE. Fig. 1.2

7 JPJC/JC2 H2 Biology/Prelim/2024 [Turn over With reference to Fig.1.2, explain the likely effect of these differences on a molecule of woolly mammoth haemoglobin (rHb WM). ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ................................................................................................................................ . ............................................................