2024 NYJC Prelim Biology P3 (A)

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDAT E NAME ANSWERS CLASS BIOLOGY 9744/03 Paper 3 Long Structured and Free-response Questions 13 September 2024 Additional Materials: Insert, Answer booklet 2 hours READ THESE INSTRUCTIONS FIRST Write your name and CT on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, 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 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 no use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 25 2 15 3 10 Section B 25 Total 75 This document consists of 13 printed pages and 1 blank page. [Turn over H

2 9744 / H2 Biology / 03 Section A Answer all the questions in this section. Information for Question 1 One way of classifying bacteria is by looking at the differences in their cell wall structure. The differences are shown by using the Gram stain. ● A Gram-positive bacterium has a cell wall mainly composed of a thick layer of peptidoglycan (murein). ● A Gram-negative bacterium has a more complex cell wall. This wall is composed of a much thinner layer of peptidoglycan and an outer layer known as the outer membrane. Escherichia coli is a Gram-negative bacterium. Fig. 1.1 is a diagram through the cell surface membrane and the cell wall of E. coli. Fig. 1.1

3 9744 / H2 Biology / 03 Bacteria reproduce asexually through binary fission. Due to their fast growth and simple genetics, bacteria such as E.coli are widely used in molecular biology. Fig. 1.2 shows a bacterial cell undergoing binary fission. Fig. 1.2

4 9744 / H2 Biology / 03 1 Part of the information required for Question 1 is presented in the insert. Cross references to Fig. 1.1 and Fig. 1.2 are included in the questions for which Fig. 1.1 and Fig. 1.2 are relevant. Bioinformatics is the collection, processing and analysis of biological data using computer software. The application of bioinformatics allows whole sequences of homologous genes to be compared across different bacterial species. (a) Explain why bioinformatics can used to compare gene sequences and suggest a conclusion that can be made from the percentage similarity data obtained. any one from: why 1 large amount of, data / DNA sequences ; 2 fast / accurate / efficient ; A description of fast / accurate / efficient / detects each small difference =