NJC_H2_CHEM_CM_QP

NJC Preliminary Examination 9812/01/17 [Turn over SUBJECT CLASS REGISTRATION NUMBER PHARMACEUTICAL CHEMISTRY Paper 1 Additional Materials: Answer Paper Data Booklet 9812/01 Friday 15 September 2017 2 hours 30 minutes READ THE INSTRUCTIONS FIRST Write your subject class, registration number and name on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer any five questions. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The use of an approved scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. This document consists of 17 printed pages and 1 blank page. NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAMINATION Higher 3 CANDIDATE NAME

2 NJC Preliminary Examination 9812/01/17 1 (a) Analgesic can be classified according to narcotic and non-narcotics analgesics. The following are 4 examples of commonly used analgesics in healthcare. paracetamol aspirin diflunisal codeine (i) Classify these 4 analgesics as narcotic or non–narcotic analgesics. [2] (ii) Outline the different ways narcotic and nonnarcotic analgesics act as pain-killer. [2] (iii) One side effect of prolonged consumption of aspirin is stomach bleeding and ulcers. Describe how aspirin causes stomach bleeding and ulcers. [2] (iv) Paracetamol is an analgesic which is capable of pain relief yet not causing stomach bleeding and ulcers as in the case of aspirin. Suggest two other advantages of using paracetamol over the use of aspirin. [2]

3 NJC Preliminary Examination 9812/01/17 [Turn over Both diflunisal and aspirin inhibit the same enzyme in its mechanism of action to reduce pain. The inhibition effect of these drugs on the target enzymes can be studied using a Michaelis–Menten graph. The higher the rate of enzymatic reactions, the greater the pain level. The inhibition effect of diflunisal against the natural substrate of the target enzyme is as shown below. (v) Suggest the type of inhibition exhibited by diflunisal. Explain your answer. [2] (vi) Copy the graph shown above on your writing paper and draw a graph illustrating the expected inhibition effect of aspirin as compared to that of diflunisal. Explain your answer. [3] (b) (i) Morphine is one of the most effective painkillers that can be extracted from dried juice obtained from unripe seed pods of opium poppy. In order to be effective as an analgesic, the morphine molecule has to pass