2017_Photosyntheis_Respiration_STQ_MS

2017 Photosynthesis and Respiration STQ MS2017 / H2 / AJC PRELIM / P2 Q61In anaerobic respiration in yeast, the pyruvate molecules are broken down to produce ethanol and carbon dioxide. The release of carbon dioxide can be used to investigate the rate of anaerobic respiration. Fig. 6.1 shows and experiment which was set up to find the rate of anaerobic respiration. Fig. 6.1The meniscus moves down the tube as carbon dioxide is released. Table 6.1 shows the distance moved by the meniscus from the start point. This was recorded every 10 minutes. Table 6.1Time/ min0102030405060708090Distance travelled by meniscus from start point/ mm012591421457398 (a)The rate of anaerobic respiration can be calculated by using the rate of movement of the meniscus.Calculate the rate of anaerobic respiration between 70 and 80 minutes. You will lose marks if you do not show your working. Rate of Anaerobic Respiration = (73-45) mm / (80-70) min= 28 mm / 10 min= 2.8 mm min-1[2(b)This experiment was repeated three more times. Each time, the glucose (a monosaccharide) was replaced with a different disaccharide sugar:Maltose – a disaccharide of glucose and glucoseSucrose – a disaccharide of glucose and fructoseLactose – a disaccharide of glucose and galactose. Tables 6.2 (a), (b) and (c) show the results of these experiments. Table 6.2 (a): Using maltose

Time/ min0102030405060708090Distance travelled by meniscus from start point/ mm00000236912Table 6.2 (b): Using sucroseTime/ min0102030405060708090Distance travelled by meniscus from start point/ mm000131122374861Table 6.2 (c): Using lactoseTime/ min0102030405060708090Distance travelled by meniscus from start point/ mm0000000000With reference to the information provided in Tables 6.2 (a), (b) and (c) and your biological knowledge:(i)Describe the difference in the results for maltose and sucrose, and suggest one explanation for this difference, Glucose is the respiratory substrate for glycolysis;Maltose: meniscus only starts moving at 50 min vs sucrose at 30 min/ movement of sucrose more than maltose + data;Enzyme to break down sucrose is more readily available/at higher concentration than enzymes to break down maltose;[2(ii)Suggest two explanations for the results for lactose. Yeast does not have proteins channels that allows uptake of lacotse;Yeast does not encode for lactase that breaks down lactose to glucose and galactose;AVP;[2(c)An electron micrograph of yeast, Candida albicans, is shown in Fig. 6.2. Fig. 6.2

(i)On Fig. 6.2, label site of i.Glycolysisii.Oxidative phosphorylation[2(ii)State one visible structure of mitochondria from Fig. 6.2 and describe how it supports mitochondria’s function. Highly folded inner membrane + Increase surface area for embedment of more ETC/ ATP synthase to increase rate of ATP productionMembrane bound/ double membrane + Enclose matrix that contains enzymes for link reaction and Kreb’s cycle/ compartmentalizes matrix for optimum conditions for enzymes to work; [1(ii)Besides location,