Biology 0610/53 May/June 2019: question paper and mark scheme

Question

Fig. 1.1 shows a section through an unfertilised chicken’s egg. The egg is made up of the outer shell, inner yellow yolk and albumen (egg white). shell yolk albumen Fig. 1.1 The albumen and yolk are composed of different substances, including fats. (a) Describe how ethanol can be used to test a sample of food for the presence of fat. Include the result for a positive test. …… [3] You should use the safety equipment provided while you are carrying out the practical work. (b) You are provided with a sample of albumen suspension in a beaker, labelled A. You are going to test the albumen suspension for the presence of protein. • Use a syringe to put 2 cm3 of albumen suspension A into a test-tube. • Add 2 cm3 of biuret solution from the beaker labelled biuret. • Mix thoroughly by gently shaking the test-tube. Describe your observations and state your conclusion. observations …… conclusion …… [2] (c) Proteins can be broken down by enzymes. You will investigate the effect of acid on the breakdown of albumen by a protease enzyme. Read all the instructions but do not carry them out until you have drawn a table for your results in the space provided in 1(c)(i). Step 1 Label three test-tubes P, Q and R and place them into the test-tube rack. Step 2 Use a syringe to add the substances, in the volumes shown in Table 1.1, to test-tubes P, Q and R. Step 3 Raise your hand when you are ready for warm water to be added to your water- bath. Place test-tubes P, Q and R into the water-bath. Table 1.1 test-tube albumen distilled acid H enzyme E suspension A water W / cm3 / cm3 / cm3 / cm3 P 2 2 0 0 Q 2 1 0 1 R 2 0 1 1 Step 4 Gently shake the test-tubes to mix the contents and then leave them in the water-bath for 10 minutes. Continue with the questions while you wait. Step 5 After 10 minutes remove test-tubes P, Q and R from the water-bath and place them in the test-tube rack. Add 2 cm3 of biuret solution to each test-tube and mix well. Step 6 Observe the appearance of the solution in each test-tube. Record your observations in your table in 1(c)(i). (i) Prepare a table to record your observations. [3] (ii) Identify the variable that was changed (independent variable) in this investigation. …… [1] (iii) State the purpose of test-tube P in this investigation. …… [1] (iv) Suggest why 1 cm3 of distilled water was added to test-tube Q. …… [1] (v) Identify one potential error in step 2. Explain how this error could affect the results. error …… effect of the error …… [2] (vi) Identify one potential safety hazard in this investigation. …… [1] [Total: 14]

Question

(a) Fig. 2.1 is a photomicrograph showing a cross-section of an artery. Fig. 2.1 Make a large drawing of the artery in Fig. 2.1 to show the layers that make up the artery wall. Do not draw individual cells. [4] (b) Fig. 2.2 shows a photomicrograph of cross-sections of an artery and a vein. vein artery B A magnification ×13 Fig. 2.2 (i) The diameter of the artery is indicated by line AB. Measure the length of line AB, on Fig. 2.2. Include the unit. length of line AB …… Calculate the actual diameter of the artery using your measurement and the formula. length of line AB magnification = actual diameter of the artery Give your answer to two significant figures. Include the unit. Show your working. [3] (ii) Describe one similarity and one difference between the artery and the vein shown in Fig. 2.2. similarity …… difference …… [2] (c) A student investigated the change in their pulse rate before and after exercise. The student measured their pulse before exercise, during exercise and after exercise. The results are shown in Table 2.1. Table 2.1 time pulse rate activity / minutes / beats per minute 2 78 before exercise 4 78 6 78 8 125 during exercise 10 148 12 160 14 154 after exercise 16 122 18 94 (i) Calculate the percentage increase in the pulse rate from minute 6 (before exercise) to minute 12 (during exercise). Give your answer to the nearest whole number. Show your working. …… % [2] (ii) Plot a line graph on the grid of time against pulse rate for the results shown in Table 2.1. [4] (iii) Use your graph to estimate the pulse rate of the student at 15 minutes. Show on your graph how you obtained your answer. …… bpm [2] (iv) Describe the results of the student’s investigation. …… [3] (d) Plan an investigation to find out how running at different speeds affects pulse rate. …… [6] [Total: 26]