SJI 2017 Bio Prelim P2 QP

1 Name: ________________________ Class: ___________ Index Number: _____ ST JOSEPH’S INSTITUTION PRELIMINARY EXAMINATION 2017 SECONDARY 4 (O LEVEL PROGRAMME) BIOLOGY Paper 2 Theory Candidates answer on the Question Paper 5158/02 16 August 2017 1 hour 45 minutes (1100 hr – 1245 hr) READ THESE INSTRUCTIONS FIRST Write your name, class and index number on the cover page of this Question Paper and all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams or graphs. Section A Answer all questions. Section B Answer THREE questions in this Section in the lined spaces provided. The first two questions are compulsory questions; one of which is a data-based question. The last question is in the either/or form. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A / 50 Section B / 30 Total / 80 This document consists of _16_ printed pages including this cover page. [Turn over]

2 Section A: 50 marks Answer ALL questions in the spaces provided. 1 Differentiate between: a a polypeptide and a protein. ................................................................................................................. ................................................................................................................. [2] b glycogen, glucagon and glycerol. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. [Total: 5] [3] 2 Fig. 2.1 shows the effect of temperature on the rate of an enzyme catalysed reaction in an aquatic green plant Elodea. Fig. 2.1 a Sketch, on Fig. 2.1, the graph showing the rate of carbon dioxide absorbed by Elodea from its surrounding over the same range of temperature, when light intensity is reduced 50% from before. [1] Temperature /oC

3 b Explain the relationship of the two graphs at temperature 50oC. ................................................................................................................. ................................................................................................................. ................................................................................................................. [2] c Explain, using the ‘lock and key’ hypothesis, the increase in rate of enzyme activity between 20oC and 30oC. ................................................................................................................. ................................................................................................................. ................................................................................................................. [Total: 5] [2] 3 In the lungs, the alveoli are the site of gas exchange. a A large number of small alveoli is more efficient in gas exchange than a smaller number of larger alveoli. Explain why. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. [2] b Figure 3.1 shows part of an alveolus and a capillary. Fig. 3.1 (i) Name the ion X in the blood plasma which enters the red blood cell and the enzyme involved to catalyse the formation of carbon dioxide which will diffuse into the air space in the alveolus. X: ………………………………. Enzyme: …………………………….. [2] X

4 (ii) State the common adaptive feature of both cell layers A and B to increase efficiency of gas exchange. ………………………………………………………………………………………………….. [1] (iii) What is the minimum distance a molecule of carbon dioxide diffuses from the blood plasma to the air space in the alveolus? ………………………………………………………………………………… [1] c The diffusion of carbon dioxide depends on the difference in its concentration between the blood and the lungs. Exhalation results in lowering the concentration of carbon dioxide of the lungs. Describe and explain the roles played by diaphragm and internal intercostal muscles to bring about exhalation of the gas. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. [Total: 10] [4] 4 Figure 4.1 shows two different cells involved in the defence of the human body. Fig 4.1 a Explain how cell X and Y may work together to prevent infection after an operation. ................................................................................................................. ................................................................................................................. ................................................................................................................. [2]

5 b Blood clot also protects infection by forming a plaque on the wound. Briefly explain how blood platelets help to form blood clot. ................................................................................................................. ................................................................................................................. ................................................................................................................. [Total: 4] [2] 5 In Vitro Fertilisation (IVF) is a medical procedure whereby egg is fertilised by sperms elsewhere outside the body. Figure 5.1 below shows a diagrammatic flow of the treatment. Fig. 5.1 a State the part of the female reproductive organ where fertilisation normally occurs instead of culture dish in IVF. ................................................................................................................. [1] b Explain why the embryos formed using IVF are not clone of their parents. ………………………………………………………………………………… ………………………………………………………………………………… [1]

6 c Briefly explain why the embryo has to be implanted into the uterus during IVF. ................................................................................................................. ................................................................................................................. ………………………………………………………………………………… ................................................................................................................. ................................................................................................................. [Total: 5] [3] 6 The food chain below shows the amount of biomass transferred to humans from 1000 g of plant plankton. 1000 g 500 g 40 g 5 g plant plankton  animal plankton  mackerel  human a Draw and label a pyramid of biomass for the food chain above. [1] b If the population in the second trophic level of the food chain is decreased, what effects on the populations of the other trophic levels may result? ................................................................................................................. ................................................................................................................. [2] c Mercury was accidentally released from a nearby factory into a water body where the plant plankton lives. Suggest how this might be harmful to human beings as part of the food chain above. .........................