PLMGSS 2024 4E ScBio P4 QP

1 [Turn over] CANDIDATE NAME CLASS CLASS INDEX NUMBER TG CENTRE NUMBER INDEX NUMBER SCIENCE (BIOLOGY) 5088/4 Paper 4 Biology 16 August 2024 No additional materials are required. 1 hour 15 minutes READ THESE INSTRUCTIONS FIRST Write your name, class and class index number on the front cover. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. The use of an approved calculator is expected, where appropriate. Section A (55 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (10 marks) There are two questions in this section. Answer only one question. Write your answers in the spaces provided on the question paper. At the end of the test, fasten all your work securely together, if applicable. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 19 printed pages. For Examiner’s Use Section A 55 Section B 10 7 8 Total 65 Paya Lebar Methodist Girls’ School (Secondary) Preliminary Examination 2024 Secondary 4 Express (G3)

2 [Turn over] Section A (55 marks) Answer all the questions in the spaces provided. 1 Digestive enzymes catalyse the breakdown of large insoluble molecules. (a) Explain why it is important that large insoluble molecules are broken down by chemical digestion. ………………………………………………………………….……………………………..…. ………………………………………………………………………………………..…... [1] (b) (i) Fig. 1.1 shows the action of an enzyme. On Fig. 1.1, use label lines and labels to identify the enzyme, product and substrate that can be found in the stomach. Fig. 1.1. [1] (ii) Define enzyme. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………………………………..…... [2]

3 [Turn over] (c) An enzyme X in biological washing pow ders speed up the removal of stains from clothing. Some of these stains may contain fats. A student investigated the effect of a bile-like substance to increase the effectiveness of the washing powder. He tested the effect of bile on the digestion of fats in milk. She used an indicator that is pink in alkaline solutions and colourless in acidic solutions. She added the same volume of indicator to each test tube. The student observed and recorded the colour of the contents of each test -tube at 0 minutes, 20 minutes and 40 minutes. Table 1.1. shows the results of the investigation. Table 1.1 set-up indicator colour observed test tube content 0 minutes 20 minutes 40 minutes A milk and bile pink pink pink B milk and enzyme X pink pink colourless C milk, enzyme X and bile pink colourless colourless (i) Name the enzyme X that will remove fat stains. ………………………………………………………………………………………..…... [1] (ii) Explain why removing fat stains and protein stains from clothing requires a washing powder that contains more than one type of enzyme. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………………………………..…... [2]

4 [Turn over] (iii) Describe and explain the difference in results between the test-tubes A, B and C. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………………………………..…... [3] [Total: 10 marks] 2 A student investigated osmosis in potato plant cells. He immersed cubes of potato tissue in water and different concentrations of sucrose solutions for 30 minutes. The masses of potato cubes were measured before and after immersion. The percentage changes in mass were calculated. Table 2.1 shows the results. Table 2.1 concentration of sucrose solution / mol dm-3 mass of potato cube before immersion /g mass of potato cube after immersion/ g percentage change in mass /% 0.00 1.32 1.42 7.6 0.20 1.32 1.38 4.6 0.40 1.35 1.36 0.7 0.60 1.33 1.29 -3.0 0.80 1.30 1.24 -4.8 1.00 1.32 1.25 …………… (a) Using the information in Table 2.1, calculate the percentage change in mass at 1.00 mol / dm-3 and complete Table 2.1. Give your answer to one decimal place. [1]

5 [Turn over] (b) (i) Using the information in Table 2.1, plot a graph to show the percentage change in mass of potato at different sucrose solutions in Fig. 2.1 below. Fig. 2.1 [3] (ii) Based on your graph in (b)(i), state the water potential of the potato cells. …………………………………………………………………………..………... [1] concentration of sucrose solution / mol dm-3 0.00 0.20 0.40 0.60 0.80 1.00 percentage change in mass / % …………………………………………………………………………..………... [1] ass/ %

6 [Turn over] (c) Using the information in Table 2.1 and Fig. 2.1, explain the results observed at the 0.4 mol dm-3 and 0.8 mol dm-3. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………………………………..…... [3] (d) Suggest and explain the expected appearance of a cell from a potato cube and a red blood cell that has been immersed in distilled water for 30 minutes. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………….……………………………..…. ………………………………………………………………………………………..…... [2] [Total: 10 marks]

7 [Turn over] 3 Mammals have a double circulation. (a) Fig. 3.1 is a diagram of a section through the heart of a mammal. The arrows show the direction of blood flow through the heart and blood vessels. Fig. 3.1 (i) Identify the structures labelled A and D. A …………………………. D …………………………. [2] (ii) State the name of the chamber of the heart with the thickest wall. ………...………………………….………………………………………………………. [1] (iii) Explain why the chamber in (a)(ii) has the thickest wall. ………………………………….………………………………………………………..……..... ………………………………….………………………………………………………..……..... ………………………………….………………………………………………………..……..... ………………………….……………………………………...…………………………. [2]

8 [Turn over] (iv) Identify the structure labelled X in Fig 3.1 and state its role in the heart. ………………………………….………………………………………………………..……..... ………………………………….………………………………………………………..……..... ………………………………….………………………………………………………..……..... ………………………….……………………………………...…………………………. [2] (b) A scientist monitored the changes in the pH in muscles before, during and after two minutes of vigorous exercise. The changes in pH are caused by the production of lactic acid. Fig. 3.2 below shows the changes in pH during and after vigorous exercise. Fig. 3.2

9 [Turn over] (i) Describe and explain the results in Fig. 3.2. 0 to 2 min …………………….………………………………………………………..……..... ………………………………….………………………………………………………..……..... ………………………………….………………………………………………………..……..... 2 to 40 min …………………….……………………………………………………..……….... ………………………………….………………………………………………………..…