c}\\text{C}$, and $60^{\\circ}\\text{C}$ M1\n- Measure the concentration of glucose produced (for example, using glucose test strips or a glucose meter) M1\n- Measure this glucose concentration after a fixed, specified time period (e.g., 10 minutes) M1\n- Keep the pH constant using a buffer solution A1\n- Keep the volume and concentration of both the milk and the lactase enzyme constant A1\n- Repeat the experiment at least three times at each temperature to calculate a mean C1","marks":6,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"2980febd-1d37-4054-bf54-ca2b7c54911e","revisionId":"0e951c06-0991-4055-9830-20e6274d5037","questionNumber":null,"questionType":"LA","specification":"A group of researchers uses a bomb calorimeter to investigate the energy density of five different seed extracts (labeled P to T) with varying lipid contents.","difficulty":5,"difficultyBand":"medium","totalMarks":8,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"31108047-d5ab-4f4c-92ea-e1904231ac29","label":"a","content":"Prior to placing the seed extracts inside the bomb calorimeter, each sample is thoroughly dehydrated to remove all water. Explain why this step improves the accuracy of the energy density determination.","markscheme":"- Water in the sample would absorb heat energy to evaporate (latent heat of vaporisation) B1\n- This would lead to an underestimation of the calculated energy content, so removing water ensures all measured heat comes from the combustion of the organic seed components B1","marks":2,"order":0,"markingRubric":null,"explanation":null,"options":[]},{"id":"b1bf1175-565f-42eb-abb0-720d2fd9f1cc","label":"b","content":"Table 1 shows the lipid content of each seed extract in grams per 100 grams of dry mass. Table 2 shows the measured energy content in kilojoules per gram (\\text{kJ/g}) across three experimental trials.\n\nTable 1: Lipid content\n| Seed Extract | Lipid content (g per 100g) |\n| :---: | :---: |\n| P | 8.5 |\n| Q | 22.4 |\n| R | 41.8 |\n| S | 59.1 |\n| T | 81.3 |\n\nTable 2: Energy content (\\text{kJ/g})\n| Seed Extract | Trial 1 | Trial 2 | Trial 3 | Calculated Mean |\n| :---: | :---: | :---: | :---: | :---: |\n| P | 3.8 | 4.2 | 4.0 | 4.0 |\n| Q | 9.2 | 9.8 | 9.5 | 9.5 |\n| R | 16.4 | 32.8 | 16.6 | 16.5 |\n| S | 23.5 | 24.1 | 23.8 | 23.8 |\n| T | 31.9 | 32.5 | 32.2 | 32.2 |\n\nIdentify the anomalous reading in Table 2, stating the seed extract and trial number. Explain how this anomaly should be treated when calculating the mean energy content.","markscheme":"- Seed R, Trial 2 ($32.8\\text{ kJ/g}$) is the anomalous value B1\n- It should be excluded from the mean calculation (meaning only Trial 1 and Trial 3 are used to calculate the mean: $\\frac{16.4 + 16.6}{2} = 16.5\\text{ kJ/g}$) B1","marks":2,"order":1,"markingRubric":null,"explanation":null,"options":[]},{"id":"185aaea3-76ab-43d2-9fec-1e6cbd119d7d","label":"c","content":"Use the data to explain whether the results support the conclusion that seed extracts with higher lipid content have a greater energy content.","markscheme":"- Yes, because as the lipid content increases from $8.5\\text{ g}$ (Seed P) to $81.3\\text{ g}$ (Seed T), the mean energy content also steadily increases from $4.0\\text{ kJ/g}$ to $32.2\\text{ kJ/g}$ B1\n- This shows a positive correlation between lipid concentration and energy density B1","marks":2,"order":2,"markingRubric":null,"explanation":null,"options":[]},{"id":"9756b965-0b84-41af-8d5f-8e6c15efd121","label":"d","content":"Name two other classes of large biological macromolecules in food, besides lipids, that contain energy.","markscheme":"- Carbohydrates (or polysaccharides / starch / glycogen) B1\n- Proteins B1","marks":2,"order":3,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"fir

Biological molecules

Question 2

Biological molecules Questions

Biological molecules

Question 2

Biological molecules Questions