2024 TJC H2 Bio P2 QP

1 [TURN OVER READ THESE INSTRUCTIONS FIRST Write your Center number, index number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show any working or if you do not use appropriate units . TEMASEK JUNIOR COLLEGE 2024 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER BIOLOGY 9744/02 Paper 2 Structured Questions 23 AUGUST 2024 2 hours Candidates answer on the Question Paper. No Additional Materials are required. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 10 2 / 9 3 / 9 4 / 13 5 / 8 6 7 8 9 10 Answer all questions. This document consists of 27 printed pages and 1 blank page.

2 Answer all questions. 1 (a) Fig. 1.1 is a diagram of a section through a mitochondrion. Fig. 1.1 (i) On Fig 1.1, use label lines and letters to label the positions where the following reactions take place: X - Link reaction Y - Krebs cycle Z - Oxidative phosphorylation [3] (ii) The four arrows, A, B, C and D, show the movement of molecules and ions. Use the letters to identify all the arrows (one or more) that show: Active transport of protons ...................................................................................................... Diffusion of carbon dioxide ………………............................................................................... [2] (b) Compare the process of oxidative phosphorylation with photophosphorylation. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2]

3 [TURN OVER (c) Apart from channel proteins that allow transport of ions, plant and animals cells also have channel proteins such as aquaporins which permits the movement of water across membranes. Explain why aquaporins are necessary. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [3] [Total: 10]

4 2 Fig. 2.1 shows the primary structure of a section of a polypeptide chain of collagen. Fig. 2.1 (a) Explain how the primary structure shown in Fig. 2.1 indicates that the structure of the polypeptide is suited to be a component of a collagen molecule. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [3] Fibroblasts are cells that synthesize and secrete collagen, which forms the extracellular matrix. Hydrolytic enzymes, known as collagenases, are secreted by some cells during wound healing. These cells also secrete inhibi tors of collagenases. The activi ty of the enzymes and inhibitors is regulated so that the development and maintenance of the extracellular matrix is controlled. (b) State and explain what the outcome will be for the composition of the extracellular matrix if collagenase inhibitor activity is high. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2]

5 [TURN OVER Collagenase has several important medical uses, such as in the treatment of burnt skin. Scientists investigated the effect of pH on the activity of collagenase at 37 °C. The results of their investigation are shown in Fig. 2.2. Fig. 2.2 (c) Explain why the activity of collagenase is lower at pH 8.0 than at the optimum pH. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [3]

6 Synthetic inhibitors have been trialed as potential treatment for diseases which are caused by a lack of regulation of collagenase activity. Fig. 2.3 shows the rate of reaction of collagenase in the absence of the synthetic inhibitor. Fig. 2.3 (d) Sketch on Fig. 2.3 the curve that is expected if the synthetic inhibitor used in the trial is a non-competitive inhibitor. [1] [Total: 9] Collagen

7 [TURN OVER 3 Adult stem cells in a tissue are often at different stages of the cell cycle. (a) Fig. 3.1 shows cells at different stages of the cell cycle. Fig. 3.1 (i) Identify the stages of mitosis occurring in the cells labelled B and C in Fig. 3.1. B ……………………………………………………………………………………………………… C ……………………………………………………………………………………………………… [2] (ii) Describe the behaviour of the chromosomes in the stage of mit osis shown in cell A. ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… …………………………….……………….…..……………….………………………………… [2]

8 (b) Distinguish between adult stem cells and zygotic stem cells. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2] (c) Other than stem cells, some human cells show a higher than normal activity of telomerase. State the type of cells with higher than normal activity of tel omerase and explain the role of telomerase in these cells. Type of cell …………………………………………………………………………………………………. Explain role of telomerase .………………………………………………………………………...…….. …………….….…………………………………………………………………………..…………………. .…………….….…………………………………………………………………………………………….. …………………….………………………………………………………………….……………………… .……………….…..………………………………………………………………………………....…… [3] [Total: 9]

9 [TURN OVER 4 Table. 4.1 shows the probabiliti es of being diagnosis with cancer in the various age groups. Each year, more than 1 million cases of cancer are diagnosed in the United States and more than 500 000 people die from the disease. Table 4.1 Cancer site Gender Age Birth to 39 40-59 60-79 Breast Female 1 in 235 1in 25 1 in 15 Prostate Male <1 in 10 000 1 in 53 1 in 7 Lung Male 1 in 3300 1 in 92 1 in 17 Female 1 in 3180 1 in 120 1in 25 Colon Male 1 in 1500 1 in 124 1 in 29 Female 1 in 1900 1in 149 1 in 33 (a) Using the information in Table 4.1, (i) state the relationship between the age of a person and the like lihood of being diagnosed with cancer; .……………….…..……………………………………………………………………………….. [1] (ii) suggest a reason for your answer in (a) (i). ……………………..…………………….…………………………………………………………… …………………………….……………