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]

4 © DHS 2023 9744/03 The reproductive success of GA German cockroaches has not been found to be significantly affected. Various studies have been conducted to investigate this phenomenon. In one study, the activity of salivary α-glucosidase in female German cockroaches was investigated in the presence and absence of acarbose. The results are shown in Fig 1.2. Edited from Wada-Katsumata A et.al, 2021. Fig 1.2 (c) Explain the significance of salivary α -glucosidase activity in female GA German cockroaches to the reproductive success of GA German cockroaches. [2] (d) (i) Identify the role of acarbose used in this investigation. [1]

5 © DHS 2023 9744/03 [Turn over Acarbose is a drug commonly used in the treatment of diabetes. Fig 1.3 shows the action of acarbose in the intestines of humans. From Rosak, Christoph & Mertes, Gabriele, 2012. Fig 1.3 (ii) Predict if acarbose would be an effective drug in the treatment of diabetes if the patient does not limit dietary sugar consumption. Explain your prediction. [3]

6 © DHS 2023 9744/03 To understand the synthesis of nuptial gift secretions in male German cockroaches, the protein content of the tergal gland was examined. The tergal gland is located at the abdomen of German cockroaches where the nuptial gift secretion is synthesized. A p rotein named BGTG -1 was identified as a protein of interest due to its increasing amounts with maturation of the male German cockroach. Its function is unknown. To identify the function of BGTG-1, the DNA sequence of the gene was compared with the full genome sequence of the well -studied fruit fly, D . melanogaster. It was found that the BGTG-1 gene was similar in sequence to the α-amylase gene. (e) Suggest how the amounts of the BGTG-1 can be regulated, after transcription, to increase with the maturation of male German cockroach. [2] (f) (i) State the term used to describe the relationship between BGTG-1 gene and α-amylase gene. [1] (ii) Explain what can be concluded about the relationship between D. melanogaster and the German cockroaches. [1]

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8 © DHS 2023 9744/03 Another protein, Bla g 2, was also identified to be secreted by the tergal glands of German cockroaches. Bla g 2 is known to cause allergies, asthma, and other ailments of the human immune and respiratory system. Fig 1.4 shows the process of allergy development. Obtained from https://www.virginiarichardson.co.uk/blog/allergyawareness Fig 1.4 (g) With reference to Fig 1.4, (i) contrast between activated mast cells during a subsequent allergen exposure and activated memory B cells during a subsequent infection, [1] (ii) explain how the structure of IgE is related to its function. [2]

9 © DHS 2023 9744/03 [Turn over (h) Explain how IgE is synthesised by IgG-synthesising plasma cells. [2] Total: [23]

10 © DHS 2023 9744/03 Question 2 The ABO gene codes for the enzyme glycosyltransferase, that adds a sugar molecule to the H antigen on red blood cells. The expression of the I A allele results in the addition of a N-acetyl-galactosamine while IB allele results in the addition of a d -galactose. IO allele results in no addition to the H antigen. Fig 2.1 shows part of the antigens. Edited from Kappler & Hennet, 2020. Fig 2.1 (a) State the organelle in which the sugar molecule is added to H antigen. [1] (b) (i) Complete Table 2 by putting a tick () in the boxes to identify the presence of the antigens on the red blood cells. Table 2 Phenotype Antigens present on the red blood cells A B H Blood type A Blood type B Blood type AB Blood type O [2]