YIJC 2023 H2 9744 P3 ANS

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 Sep 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 18. 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. This document consists of 25 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 ANSWERS

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 , s uggest and explain a hypothesis that may account for the trends of each of the diseases shown in Table 1.1. breast cancer 1 incidence rate increased from 149 to 188 per 100 000 women from 2010 to 2020 2a due to increased awareness of need for early screening resulting in early detection/ reporting; 2b due to increase in proportion of fatty food in diet, thus increasing cancer risk; 2c due to decrease in physical activity/ exercise among women, thus increasing cancer risk; 2d due to increase in cigarette smoking among women, thus increasing exposure to chemical carcinogens that promote cancer development; tuberculosis 3 incidence rate decreased from 7.2 to 3.5 per 100 000 women from 2010 to 2020 4a due to progressive use of antibiotics against Mycobacterium tuberculosis, thus reducing number of infected people in population; 4b due to effective vaccination programme against tuberculosis, thus maintaining herd immunity in population;

3 @YIJC 9744/03/PE/2023 [Turn Over 4c due to advancement in methods for faster detection and isolation of infected people, thus minimizing spread of disease; AVP; [4] (ii) Explain why tuberculosis is considered an infectious disease while breast cancer is not. 1 tuberculosis is caused by a bacteria/pathogen/ Mycobacterium tuberculosis while breast cancer is a genetic disease resulting from (accumulation of) mutations to cancer-related genes/ not caused by a pathogen; 2 tuberculosis can be transmitted from one individual to another via airborne/aerosol droplets while breast cancer cannot be transmitted from one individual to another; [2]

4 @YIJC 9744/03/PE/2023 [Turn Over (b) Epidemiological studies suggest that 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. Ty pe 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 “People with type 2 diabetes are at higher risk of cancer.” Using Fig. 1.1, discuss if the above statement is valid. 1 statement is valid for colorectal cancer; 2 whereby people with type 2 diabetes have a higher cancer incidence quote relevant data to illustrate cancer incidence is consistently higher across the years for people with type 2 diabetes than those without (A: quote range); 3 statement is not valid for prostate cancer;

5 @YIJC 9744/03/PE/2023 [Turn Over 4 whereby people with type 2 diabetes have a lower cancer incidence than those without 25 per 100 000 people vs 35 per 100 000 people (A: quote range); 5 statement cannot be concluded for breast cancer; 6 no clear distinction between cancer incidence rates of people with and without diabetes quote same average incidence/ similar range; [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. 1 cancer results from accumulation of mutations to cancer-related genes e.g. tumour suppressor genes and proto-oncogenes; 2 as person ages, increased exposure to mutagens (e.g. chemical carcinogen s/ ionising radiation) increases mutations to such genes to result in uncontrolled cell division; [2] (ii) Suggest one reason why the risk of type 2 diabetes increases with age. as person ages, effects of unhealthy diet/ lack of exercise accumulates to result in diabetes; [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 R no Fig. 1.4 R no Fig. 1.5 Q yes Fig. 1.6 P yes [4] (ii) Distinguish between the structures of a triglyceride and a fatty acid. 1 triglyceride contains 1 glycerol and 3 fatty acid chains/ tails; 2 fatty acid contains hydrocarbon chain with carboxyl/ carboxylic acid group; [2] (ii) 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. 1 cholesterol regulates memb fluidity by increasing memb fluidity at low temp/ decreasing memb fluidity at