EJC 2023 H2 9744 P2 (QP)

©EJC 2023 9744//02/J2H2PRELIM/2023 [Turn over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examinations 2023 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 2 - REGISTRATION NUMBER H2 Biology Paper 2 Structured Questions 9744/02 14 September 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on all the work you hand in. Candidates are to answer: All questions on the Question Paper. Write your answers in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue, or correction fluid/tape. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 28 printed pages. For Examiner’s Use 1 2 3 4 5 6 7 8 9 10 Total

2 ©EJC 2023 9744/02/J2H2PRELIM/2023 Answer all questions. 1 Fig. 1.1 shows an electron micrograph of a eukaryotic cell. (a) (i) Fill in the table to identify structures A and D and describe their functions. structure identity function A D [2] Fig. 1.1 B 2 µm D A C

3 ©EJC 2023 9744/02/J2H2PRELIM/2023 [Turn over (ii) Using the width of structure C as indicated by the arrow in Fig. 1.1 , calculate the magnification of the electron micrograph. Show your working clearly. [2] (b) Fig. 1.2 is an electron micrograph of three cells of the same species of bacterium, Erwinia carotovora. (i) Name two structures found in animal cells which are not present in the cells shown in Fig. 1.2. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ……………………………………………………………………………………………….[2] Fig. 1.2

4 ©EJC 2023 9744/02/J2H2PRELIM/2023 (ii) E. carotovora is a rod-shaped bacterium. Explain why two of the bacterial cells in Fig. 1.2 do not appear rod-shaped. …………………………………………………………………………………………………. ………………………………………………………………………………………………[1] (iii) Scientists think that the origins of structures B and C of Fig. 1.1 were very different from that of eukaryotic cells. The evidence for this is that they both have features in common with bacterial cells like E. carotovora. Compare the structural features of B and/or C with E. carovotora; …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. …………………………………………………………………………………………………. ………………………………………………………………………………….……………[3] [Total: 10]

5 ©EJC 2023 9744/02/J2H2PRELIM/2023 [Turn over 2 Fig. 2.1 is a representation of a starch molecule. Starch is a polysaccharide made up of amylose and amylopectin. (a) (i) Using arrows, label clearly on Fig. 2.1, amylose and amylopectin. [1] (ii) Explain how one structural feature of amylopectin is related to its function in living organisms. …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………… …………………………………………………………………………………………………[3] Fig. 2.1

6 ©EJC 2023 9744/02/J2H2PRELIM/2023 (b) Cellulose is another polysaccharide. Fig. 2.2 shows three monomers from a molecule of cellulose. (i) State the name of the monomer that makes up cellulose. ……………………………………………………………………………………………………[1] (ii) Cellulose has high tensile strength which makes it suitable for the cell walls of plants. Explain how cellulose has such a high tensile strength making it suitable for the cell walls of plants. ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… …………………………………………………………………………………………………...[3] (c) Glycogen has a similar structure to amylopectin. Glycogen is stored in the liver, kidney, and muscles of mammals. State two ways in which the structure of glycogen differs from the structure of cellulose. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ……………………………………………………………………………………………………………. ………………………………………………………………………………………………….………[2] [Total: 10] Fig. 2.2

7 ©EJC 2023 9744/02/J2H2PRELIM/2023 [Turn over 3 Neutrase® is an enzyme that is used to hydrolyse proteins in solution. When the enzyme is mixed with a 2% protein solution, the reaction mixture changes from white to colourless. A student carried out an experiment to find the effect of copper sulfate and potassium sulfate on the activity of Neutrase®. The student made four reaction mixtures in test-tubes A to D. The contents of each test-tube are shown in Table 3.1. Table 3.1 test- tube volume added / cm 3 2% protein 0.05 mol dm–3 copper sulfate 0.01 mol dm–3 copper sulfate 0.01 mol dm–3 potassium sulfate water A 0.1 0.1 0.0 0.0 0.0 B 0.1 0.0 0.1 0.0 0.0 C 0.1 0.0 0.0 0.1 0.0 D 0.1 0.0 0.0 0.0 0.1 0.5 cm3 of a 1% Neutrase® solution was then added to test-tube A and immediately placed into a colorimeter. The colorimeter was used to measure the intensity of light that is absorbed by the solution (absorbance) over 100 seconds. The procedure was repeated with the other reaction mixtures, B, C and D. The results are shown in Fig. 3.1. Fig. 3.1

8 ©EJC 2023 9744/02/J2H2PRELIM/2023 (a) (i) Suggest and explain why measuring the absorbance of the reaction mixture o ver 100 seconds is a suitable method for determining the activity of Neutrase®. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... .......................................................................................................................................[2] (ii) With reference to Fig. 3.1, describe the effects of 0.01 mol dm-3 copper sulfate solution and 0.01 mol dm-3 potassium sulfate solution on the activity of Neutrase®. copper sulfate .................................................................................................................... ........................................................................................................................................... ....................................................................................................................