VJC 2021 H2 Bio 9744 P2 QP

1 VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION 2021 HIGHER 2 NAME : ……………………………………………………….………………. CT CLASS: ………………..……… BIOLOGY Paper 2 Structured Questions 9744/02 13/09/2021 2 hour Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name and CT class 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. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in bracket [ ] at the end of each question or part question. Question Marks 1 2 3 4 5 6 7 8 9 10 Total This document consists of 22 printed pages. [Turn over]

2 Answer all questions. 1 Cells in the pancreas secrete enzymes, such as amylase and trypsin, into a duct. The enzymes are packaged in vesicles so that they can be exported from these cells as shown in Fig. 1.1. Fig. 1.1 (a) Outline how the enzymes are packaged into vesicles and released to the outside of the cell. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [4]

3 (b) Explain how the structure of the vesicle shown in Fig. 1.1 allows it to serve its function. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [3] (c) Researchers are interested in using the vesicles to deliver drugs to specific cells. Suggest and explain one modification to the vesicles to allow them to deliver the drugs to specific cells. …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [2] (d) Describe two differences between the release of enzymes shown in Fig . 1.1 and the release of flu viruses from the host cell. …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [2] [Total: 11]

4 2 Fig. 2.1 shows the structure of a natural triglyceride. Fig. 2.1 (a) (i) On Fig. 2.1, circle and label all the saturated and unsaturated fatty acid chains. [2] (ii) Explain how the structure and properties of triglyceride is related to its role in living organisms. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [3]

5 (b) Triglycerides, such as the one shown in Fig. 2.1, can be catalysed by lipase. Fig. 2.2 shows the reaction. Fig. 2.2 With reference to Fig. 2.2, explain the mode of action of lipase. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [4] [Total: 9]

6 3 Keratin is one of the most important structural proteins in nature and is widely found in many parts of vertebrates such as the skin, hair, horn and beak. Fig. 3.1 below shows the organis ation of polypeptide chains that make up keratin in the hair. Fig. 3.1 (a) (i) With reference to Fig. 3.1, describe one difference and two similarities between the organisation of polypeptide chains in keratin and collagen. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [3] (ii) Suggest how the structural organisation of keratin enables it to fulfil its function. …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [2]

7 Collagen polypeptides consist of approximately 1000 amino acid residues. After their synthesis, collagen polypeptides are secreted out of the cell before assembly. (b)(i) Explain the significance of the amino acid sequence to the function of collagen. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [4] (ii) Suggest why assembly of collagen cannot take place in the cytoplasm. …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [1] [Total: 10]

8 4 Several changes are observed as a cell prepares to undergo mitosis. To begin mitosis, a complex termed the mitosis -promoting factor, MPF phosphorylates proteins important in prophase. These proteins include: • lamins, which are fibrous proteins that support the inner nuclear membrane and • condensins, which are important in the packing of DNA. Fig. 4.1 shows changes to the nuclear envelope and the genetic material as the cell progresses through the cell cycle. Fig. 4.1 (a) With reference to Fig . 4.1 and your knowledge, suggest how phosphorylation of condensins and lamins prepares the cell for mitosis. …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [2] (b) Outline briefly the role of the microtubules in the formation of clones in mitosis. …………………………………………………………………………………….………………... ………………………………………………………………………………….…………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... …………………………………………………………………………………….………………... ………………………………………………………………………………………………….. [3]

9 Pancreatic cancer is an almost universally lethal disease. It is predominantly a disease of the elderly, with men and women having an approximately equal risk. Many genes are involved in the development of pancreatic cancer. Table 4.1 shows four of these genes, Table 4.1 Genes Genetic changes observed P Homozygous deletion Q Hypermethylation of the gene promoter R Substitution in codon 12 S Amplification of gene (c) Using the data in Table 4.1, identify an oncogene and a mutated tumor suppressor gene. Explain your answer. (i) oncogene …………………………………………………………………………………….………………... ……………………