YIJC 2023 H2 9744 P3 QP

1 @YIJC 9744/03/PE/2023 [Turn Over YISHUN INNOVA JUNIOR COLLEGE JC2 PRELIMINARY EXAM Higher 2 NAME INDEX NO CG BIOLOGY Paper 3 Long Structured and Free-Response Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/03 15 September 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your name and class in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in the spaces provided on the Question Paper. Indicate the question you have attempted at the top of page 15. 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. Overall Results for H2 Biology Preliminary Examination Paper Raw Marks Weighting (%) Weighted score Grade 1 30 15 100 2 100 30 100 3 75 35 100 4 55 20 100 This document consists of 19 printed pages and 1 blank page. For Examiner’s Use Section A 1 30 2 10 3 10 Section B 4 or 5 25 Total 75

2 @YIJC 9744/03/PE/2023 [Turn Over Section A Answer all questions in this section. 1 (a) Table 1.1 shows the incidence rates per 100 000 women for tuberculosis and breast cancer in Sweden from 2010 to 2020. Table 1.1 year incidence rate per 100 000 women per year breast cancer tuberculosis 2010 149 7.2 2012 157 6.6 2014 175 5.8 2016 179 5.1 2018 184 4.9 2020 188 3.5 Medical treatment, preventative measures, diet and lifestyle have changed over this time period and may account for the trends shown in Table 1.1. (i) With reference to Table 1.1 and the information provided, suggest and explain a hypothesis that may account for the trends of each of the diseases shown in Table 1.1. breast cancer tuberculosis [4]

3 @YIJC 9744/03/PE/2023 [Turn Over [BLANK PAGE]

4 @YIJC 9744/03/PE/2023 [Turn Over (ii) Explain why tuberculosis is considered an infectious disease while breast cancer is not. [2] Epidemiological studies suggest that the incidence of cancer is associated with type 2 diabetes. Type 2 diabetes is a form of diabetes that is characterised by high blood sugar levels and insulin resistance, whereby cells do not respond properly to insulin . Type 2 diabetes is thought to be attributed to lifestyle factors. One study in Sweden investigates the incidence rates of various types of cancer in people with and without type 2 diabetes from 1998 to 2013. Fig. 1.1 shows some of the results of the study. Fig. 1.1

5 @YIJC 9744/03/PE/2023 [Turn Over (b) “People with type 2 diabetes are at higher risk of cancer.” Using Fig. 1.1, discuss if the above statement is valid. [6] (c) Age has been identified as a risk factor common to both cancer and type 2 diabetes. In economically developed countries, 78% of all newly diagnosed cancer cases are among individuals aged 55 years and older. In the US, it is reported that the prevalence of type 2 diabetes among those 60 years or older is almost ten-fold the prevalence of type 2 diabetes among those between 20 to 39 years of age. (i) Explain why the risk of cancer increases with age. [2] (ii) Suggest one reason why the risk of type 2 diabetes increases with age. [1]

6 @YIJC 9744/03/PE/2023 [Turn Over (d) Apart from age, diet has also been identified as a risk factor for type 2 diabetes. Many research studies have attempted to investigate the relationships between: • the percentage of energy intake in the diet that comes from saturated fatty acids and the risk of developing type 2 diabetes; • the concentration of low -density lipoprotein (LDL) in the blood and the risk of developing type 2 diabetes. Fig. 1.2 shows three proposed causal links between diet and type 2 diabetes as arrows P, Q and R. For example, the causal link represented by arrow P is the idea that an increase in saturated fatty acids in the diet causes an increase in the concentration of LDL in the blood. Fig. 1.2 The findings from some of these research studies are shown in Fig. 1.3, Fig. 1.4, Fig. 1.5 and Fig. 1.6.

7 @YIJC 9744/03/PE/2023 [Turn Over (i) Complete Table 1.2 to show for each set of results: • which of the causal links of the proposed in Fig. 1.2 were investigated (write P, Q or R) • whether the results support the casual link shown by this arrow (writes yes or no). Table 1.2 results casual link investigated do the results support the causal link? Fig. 1.3 Fig. 1.4 Fig. 1.5 Fig. 1.6 [4] (ii) Distinguish between the structures of a triglyceride and a fatty acid. [2] (iii) Low-density lipoprotein (LDL) is commonly known as “bad cholesterol”, while high - density lipoprotein (HDL) is commonly known as “good cholesterol”. State two roles of cholesterol in cells. [2]

8 @YIJC 9744/03/PE/2023 [Turn Over (e) In considering the possible biological links between diabetes and cancer risk, the role of insulin receptors in mediating cellular responses to elevated blood glucose levels ( hyperglycaemia) is of interest. Most cancer cells exhibit an increased expression of insulin-like growth factor (IGF) receptors. Fig. 1.7 shows a signal transduction pathway triggered by insulin binding to an IGF receptor on the cell surface membrane. PI3K, Akt and mTOR are protein kinases while NF-κ β is a transcription factor. Fig. 1.7 (i) Explain why insulin needs to bind to a cell surface receptor in order to trigger downstream cellular responses. [2]

9 @YIJC 9744/03/PE/2023 [Turn Over (ii) With reference to Fig. 1.7 and your knowledge of insulin receptors, describe how hyperglycaemia may lead to the synthesis of proteins involved in tissue invasion and metastasis. [5] [Total: 30]

10 @YIJC 9744/03/PE/2023 [Turn Over 2 In the detection of sickle-cell anaemia, part of the β -globin gene is first amplified using Polymerase Chain Reaction (PCR), with the help of Taq polymerase and specially designed primers. Fig. 2.1 shows the specific location of target sequence within the DNA. Fig. 2.1 (a) (i) With reference to Fig. 2.1, state the pair of 15-nucleotide long primers which can be used in the amplification of the target sequence. [2] (ii) Explain one advantage and one limitation of using Taq polymerase instead of the DNA polymerase from Escherichia coli originally used in PCR. [2] In the restriction digestion step, the restriction enzyme, MstII, is used to cut the amplified DNA sequence into fragments to distinguish between the normal β-globin allele (HbA) and the mutant allele (HbS). Fig. 2.2 shows the two alleles and their respective restriction sites for MstII. Fig. 2.2