NYGH 2012-S3EOY-Bio P2

Class Register Number Name 南洋女子中学校 NANYANG GIRLS’ HIGH SCHOOL End-of-Year Examination 2012 Secondary Three BIOLOGY 1 hour 45 minutes Paper 2 Theory Paper 0915 - 1100 Friday 12 October 2012 Additional materials: Writing papers READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name, register number and class in the spaces at the top of this page and on any separate answer paper used. Section A (40 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (30 marks) Answer all questions including questions 6, 7 and 8 Either or 8 Or. Write your answers on the separate writing papers provided. At the end of the examination, 1. fasten all your work securely together; 2. tick 8 Either (for Either) or 8 Or (for Or) next to the number 8 in the grid below to indicate which question you have answered. INFORMATION FOR CANDIDATES Examiner’s Use Section A Section B 6 7 8 Either 8 Or Total The intended number of marks is given in the brackets [ ] at the end of each question or part question. You are advised to spend no longer than one hour on Section A and no longer than 45 minutes on Section B. Setters: F-YYM, OC, AM This document consists of 13 printed pages. NANYANG GIRLS’ HIGH SCHOOL [Turn over 2012 End-of-Year Examination Secondary Three 2 Nanyang Girls’ High School Setters: F-YYM, OC, AM Biology /II Section A Answer all questions. Write your answers in the spaces provided. A1 (a) State the function of the cell plasma membrane. [ 1 ] (b) In the 1970s, scientists Larry Frye and Michael Edidin studied the structure of the cell plasma membrane extensively. In one of their experiments, they labeled the plasma membrane proteins of a mouse cell and a human cell with two different markers and fused the cells (note: markers are scientific tools which can be used to label and distinguish different components). Using a microscope, they observed the distribution of the markers in the hybrid cell, which is a cell that results from a fusion of cells from different species. Figure 1b shows the result of the distribution of the markers on the hybrid cell. Figure 1b Source: L.D. Frye and M. Edidin (1970). The rapid intermixing of cell surface antigens after formation of human-mouse heterokaryons, Journal of Cell Science, 7: 319. (i) State one function of plasma membrane proteins. [ 1 ] (ii) Explain how the results of the experiment supported the 'fluid mosaic model' of cell plasma membrane. [ 2 ] Mouse cell Human cell Fusion of cells Distribution of protein markers in hybrid cell + membrane proteins

2012 End- of-Year Examination Secondary Three 3 Nanyang Girls’ High School Setters: F-YYM, OC, AM Biology /II [Turn over (c) Cholesterol is the most abundant lipid in the cell plasma membrane. In an experiment, the effect of temperature on the amount of cholesterol in cell plasma membrane of two different species of copepods - Calanus finmarchicus and Temora longicornis were investigated. Copepods are small animals found in freshwater and in the sea. Figure 1c shows the results of the investigation. Figure 1c Source: R.P. Hassett and E.L. Crockett (2007). Habitat temperature is an important determinant of cholesterol contents in copepods, Journal of Experimental Biology, 212: 71. (i) Describe the effect of temperature on the amount of cholesterol in cell plasma membrane in the copepods. [ 1 ] (ii) Explain how the change in amount of cholesterol may allow the copepods to survive better at warmer temperatures. [ 2 ] (d) State two differences between diffusion and facilitated diffusion. [ 2 ] 1. 2. Cholesterol / µg mg-1 protein 14 12 10 8 6 4 2 0 C. finmarchicus T. longicornis 6°C 6°C18°C 18°C 2012 End-of-Year Examination Secondary Three 4 Nanyang Girls’ High School Setters: F-YYM, OC, AM Biology /II (e) The unicellular organism, Paramecium caudatum, usually lives in pond water which has less negative water potential to the cell. The P. caudatum does not burst as it contains a contractile vacuole that pumps out water as fast as it gets in. Figure 1e shows an electron micrograph of a P. caudatum. Figure 1e Source: http://www.magrinscience.com/paramecium-lab/ If a P. caudatum swims from a hypotonic environment to an isotonic environment, how will the activity of the contractile vacuole change? Explain your answer. [ 2 ] Total [ 11 ] A2 (a) Figure 2a below shows the energy graph of a catalysed chemical reaction, C+D Æ A+B. Figure 2a (i) On Figure 2a, draw an arrow (using coloured ink) to label clearly the activation energy of the reaction with the symbol E a. [ 1 ] contractile vacuole C + D A + B Time Energy

2012 End- of-Year Examination Secondary Three 5 Nanyang Girls’ High School Setters: F-YYM, OC, AM Biology /II [Turn over (ii) With reference to the activation energy of the reaction, explain how the addition of an enzyme affects the rate of reaction. [ 2 ] (b) Ginger milk curd is a Chinese dessert prepared using the following recipe. Recipe: 1. Grind the ginger to obtain some ginger juice. 2. Boil the milk. 3. Wait for the temperature to drop to about 65 °C. 4. Pour 220 cm 3 of milk into 15 cm3 of ginger juice. 5. Ginger milk curd is formed as the milk coagulates. Jamie conducted an investigation. See followed the steps in the recipe with the use of raw ginger juice for one set-up and boiled ginger juice in another set-up. (i) Predict the results of her investigation. [ 1 ] (ii) Explain your predicted results in b(i). [ 2 ] Total [ 6 ] A3 (a) Describe how the structure of chloroplast is related to its function. [ 3 ] 2012 End-of-Year Examination Secondary Three 6 Nanyang Girls’ High School Setters: F-YYM, OC, AM Biology /II (b) Shu Shan wanted to investigate the effect of temperature on the rate of photosynthesis. Her experimental plan is shown in Figure 3b below. Procedure: 1. Set up the experiment as shown above. 2. Add ice cubes and / or turn on flame to achieve correct temperature. 3. Count number of bubbles the plant produces over 1 hour for temperatures of 10, 20, 30, 40, 50 and 60 oC. 4. Record data and plot graph. Figure 3b (i) State why the lamp does not contribute a major source of error in the experiment. [ 1 ] (ii) Describe four ways to remove the sources of error in the experiment. [ 4 ] swirl with thermometer to read the temperature add ice cubes to decrease temperature calcium hydroxide solution (to detect presence of CO2) Elodea lamp Bunsen burner to increase temperature

2012 End- of-Year Examination Secondary Three 7 Nanyang Girls’ High School Setters: F-YYM, OC, AM Biology /II [Turn over (c) Figure 3c shows a photomicrograph of the cross section view of an Elodea leaf. Figure 3c With reference to the photomicrograph, explain three features of the leaf that allows the Elodea to be adapted to an aquatic (submerged) habitat. [ 3 ]