T3W4 SCGS 2023 4OLP Bio Prelim P2

1 SINGAPORE CHINESE GIRLS’ SCHOOL PRELIMINARY EXAMINATION CANDIDATE NAME CLASS REGISTER NUMBER CENTRE NUMBER INDEX NUMBER BIOLOGY 6093/02 Paper 2 Wednesday 23 August 2023 1 hour 45 minutes No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your class, index number and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. Section A Answer all questions. Section B Answer all questions. The last question has a choice of parts to answer. The use of an approved scientific calculator is expected, where appropriate. 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. T his question paper consists of 19 printed pages and 2 blank pages. For Examiner’s Use Section A 50 Qn 7 10 Qn 8 10 9 10 Total 80

2 Section A Answer all questions. Write your answers in the spaces provided. 1 Fig. 1.1 sho ws how a blocked blood vessel outside the heart can be by passed using an artificial blood vessel. Fig. 1.1 (a) Name the blocked blood vessel and vessel A respectively. blocked blood vessel: ………………………………………… vessel A: ……………………………………………………….. [2] (b) Describe how the blocked blood vessel in Fig 1.1 can affect the normal functioning of the heart. ............................................................................................................................... ............................................................................................................................... ............................................................................................................................ .[2] vessel A artificial blood vessel fixed into vessel A blocked blood vessel

3 (c) Sometimes, instead of using an artificial blood vessel, a vein from another part in the patient’s body may be used. Suggest two ways in which a vein might not be suitable for this purpose. 1. ............................................................................................................................... ................................................................................................................................... 2. ............................................................................................................................... ............................................................................................................................... [2] (d) Fig. 1.2 shows a cross-section of the same blocked blood vessel in Fig 1.1, with a ‘stent’ in place. Fig. 1.2 (i) Name a substance that can cause the blockage B. ....................................................................................................................... [1] (ii) Insertion of the ‘stent’ can cause damage to the surrounding tissues around the blockage B. Suggest and explain why patients are given ‘anti-platelet’ drugs before inserting the ‘stent’. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ....................................................................................................................... [2] B blood vessel with blockage B same blood vessel with ‘stent’ in place a ‘stent’ (a small tube of stainless steel mash)

4 (e) The blood in blood vessel A contains 20 cm3 of oxygen per 100 cm3 of blood. 98.5% of the oxygen is carried in red blood cells. The remaining percentage is carried in the blood plasma. Calculate the volume of oxygen carried in the blood plasma per 100 cm3 of blood. Show your working. ……………………cm 3 per 100 cm3 of blood [1] [Total: 10 marks]

5 2 Fig. 2.1 shows a diagram of a developing mammalian foetus and part of the uterus wall. Fig. 2.1 (a) Identify C and D. C: ………………………………………… D: ………………………………………… [2] (b) State two functions of D. 1. ................................................................................................................................ ................................................................................................................................... 2. ................................................................................................................................ ............................................................................................................................... [2] (c) Suggest how smoking affects the supply of oxygen and nutrients to structure E during pregnancy. ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ............................................................................................................................... [3] spongy lining of uterus C D E

6 (d) Fig 2.2 shows the tissues of the mother and foetus in the placenta of humans. The maternal blood and foetal blood remain separate. Fig 2.2 (i) State two reasons why the foetal blood must not mix with the maternal blood. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ....................................................................................................................... [2] (ii) The placenta is often described as “a small intestine, a lung and a kidney”. Explain how the placenta functions like each of these organs. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................