2024 SAJC Prelim Biology P2 (Q)

1 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations Civics Group Index Number Name (use BLOCK LETTERS) ST. ANDREW’S JUNIOR COLLEGE 2024 JC2 PRELIMINARY EXAMINATIONS H2 BIOLOGY 9744/2 Paper 2 (Set A – Qn 1-5) Friday 23rd August 2024 2 hours Materials: Question Paper Set A and Set B READ THESE INSTRUCTIONS FIRST Write your name, civics group and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagram, graph or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. Write your answers in the spaces provided on the question paper. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiners’ Use 1 /10 2 /10 3 /12 4 /10 5 /9 6 /10 7 /10 8 /10 9 /5 10 /4 Total /100 This document consists of 15 printed pages and 0 blank page. [Turn over H2

2 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations QUESTION 1 (a) Table 1.1 lists cell structures that can be found in eukaryotic cells or prokaryotic cells. Some of these cell structures can be found in both types of cell. Complete the table using a tick () to show that the cell structure can be present in a particular type of cell and a cross (✗) to show that the cell structure cannot be present. Put a tick or a cross in every box. The top row has been completed for you. Table 1.1 Cell structure eukaryotic cells prokaryotic cells Nucleus   Golgi body circular DNA 70S ribosome [2]

3 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations (b) All cells have a cell surface membrane. Fig. 1.1 shows a transmission electron micrograph of part of two adjacent animal cells, cell 1 and cell 2. Fig. 1.1 In the space provided, draw a diagram of the region in the box labelled R in Fig. 1.1. Your diagram should show the four dark lines. Label the diagram to identify what is shown by the dark lines and each of the three spaces between them. [3] R

4 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations Fig. 1.2 is a transmission electron micrograph of part of a hepatocyte showing some cell structures. The peroxisome shown in Fig. 1.2 is a spherical organelle bound by a single membrane. I t carries out a variety of enzyme -catalysed metabolic reactions, including detoxification. Some of these reactions require oxygen. Fig. 1.2 (c) The mitochondria in Fig. 1.2 are larger than the peroxisome. (i) State one other difference, visible in Fig. 1.2, between a peroxisome and a mitochondrion. …………………………………………………………………………...…………….………… ……………………………………………………………………...………………….………[1] Some of the enzymes used within mitochondria can be synthesised by the organelle. Peroxisomes cannot synthesise any of the enzymes that they contain. (ii) Suggest why a mitochondrion can synthesise enzymes, but a peroxisome cannot synthesise enzymes. …………………………………………………………………………...……………………… ………………………………………………………………………………...………………… ……………………………………………………………………………………...…………… …………………………………………………………………………………………...……… ………………………………………………………………………………………………...… ………………………………………………………………………………..……….………[2]

5 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations (iii) One of the enzymes present in peroxisomes is catalase. This enzyme catalyses the breakdown of hydrogen peroxide to harmless products. Suggest why it is useful to the cell for this reaction to take place within peroxisomes. …………………………………………………………………………...……………………… …………………………………………………………………………………………………… …………………………………………………………...……………………………………… ………………………………………………………………...………………………………… ……………………………………………………………………...……………………...…[2] [Total: 10]

6 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations Question 2 Fig. 2.1 outlines the first three stages of respiration in aerobic conditions. Fig. 2.1 (a) Name molecule Y in Fig. 2.1. …………………………………………………………………………...………………..………[1]

7 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations (b) At one time it was thought that the oxidative phosphorylation of: • one molecule of reduced NAD results in the synthesis of 2.5 ATP molecules • one molecule of reduced FAD results in the synthesis of 1.5 ATP molecules. Using Fig. 2.1, a theoretical value for the net number of ATP molecules that are synthesized for each molecule of glucose can be calculated . Modern research has shown that the actual net number of ATP molecules synthesised for each glucose molecule respired is much l ower than this theoretical value. (i) Using Fig. 2.1, calculate the theoretical value for the net number of ATP molecules that are synthesised for each molecule of glucose respired in all phosphorylation reactions. Show your working. answer = ....................................................... [2] (ii) Suggest two reasons why the actual net number of ATP molecules synthesised is less than the theoretical number. …………………………………………………………………………...………..……………… …………………………………………..………………………………………………………… …………………………………………………………………………...………..……………… …………………………………………..………………………………………………………… ...……………………………………………………………………………………..…………… …….……………………………………………………………………………………………… ………...………………………………………………………………………………….……[2]

8 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations (c) Outline the roles of NAD and FAD in aerobic respiration. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… ………………………………………………………………………...………………………..…[2] (d) Rotenone is used as an insecticide. Rotenone kills insects by inhibiting the transfer o f electrons in the electron transport chain of the mitochondrion. Explain how r otenone affects ATP synthesis in the mitochondrion. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………...……………[3] [Total: 10]

9 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations Question 3 The polymerase chain reaction (PCR) is used to produce large amounts of haemoglobin gene DNA from a very small original DNA sample. The main stages of a PCR are shown in Fig. 3.1. Fig. 3.1 (a) (i) Explain why the DNA sample is heated to 95°C in step 1. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………..……………………………………………………...…………………………[2] (ii) Explain why primers are added in step 2. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… ………………………………………………………………………...…………………………[2]

10 St Andrew’s Junior College 2024 9744/02/Preliminary Examinations (iii) Explain why the enzyme Taq polymerase is used in step 3. …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …………………………………………………………………………...…………………………… …...……………………………………………………………………...…………………………[2] (b) Gel electrophoresis can be carried out to test individuals for the differen t versions of haemoglobin: Adult haemoglobin(HbA ) , Sickle cell haemoglob