DHS 2023 H2 Prelim Paper 3

© DHS 2023 9744/03 [Turn over Name: Centre/Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination Year 6 H2 BIOLOGY 9744/03 Paper 3 Long Structured and Free-Response Questions 21 September 2023 Additional Materials: Answer Booklet 2 hours READ THESE INSTRUCTIONS FIRST: Write your centre number, index number, name and class 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. Sections A Answer all questions in the spaces provided on the Question Paper. Sections B Answer any one free-response question in the 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 Section A / 50 1 23 2 15 3 12 Section B / 25 4 / 5 25 Total 75 This document consists of 16 printed pages and 2 blank pages.

2 © DHS 2023 9744/03 Section A: Long Structured Questions Answer all questions. Question 1 As a worldwide public health pest, German cockroaches have been exposed to insecticides formulated in glucose- containing baits. The use of these insecticides is believed to have driven the evolution of glucose- averse (GA) German cockroaches that are behaviourally resistant against these baits. (a) Explain how the use of insecticides drove the evolution of GA German cockroaches. [3] During courtship, wildtype (WT) male German cockroaches produce secretions, containing maltose and other oligomers, and present it to the females as a highly palatable nuptial gift. Upon accepting the gift, the female German cockroach allows the male to mate for as long as it feeds on the secretion. α-glucosidase is present in the saliva of female German cockroaches to release α-glucose from carbohydrates. Fig 1.1 shows the nuptial feeding duration of WT and GA female German cockroaches with nuptial gift presented by WT males. Each dot represents a pair or mating, and the line represents the mean nuptial feeding duration. Edited from Wada-Katsumata A, Hatano E, Schal C., 2023. Fig 1.1

3 © DHS 2023 9744/03 [Turn over (b) (i) Describe the hydrolysis of maltose by α-glucosidase. [1] (ii) With reference to Fig 1.1, suggest a reason for the difference in nuptial feeding duration. [2] (iii) It is believed that the longer the nuptial feeding duration, the higher the mating success. Explain why the survival of German cockroaches is expected to be at stake. [2]

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