llow, orange, or brick-red (or formation of a red precipitate) B1","marks":3,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"benedicts_test","label":"Benedict's test","steps":[{"type":"text","order":1,"title":"Add the reagent","content":"Place some urine in a test tube, then add **Benedict's reagent** (also called Benedict's solution). This is the chemical test used to detect glucose (a reducing sugar).\n\nThis stated addition earns **B1**.","highlights":[{"text":"test a sample of the dog's urine","location":"specification"}]},{"type":"text","order":2,"title":"Heat the mixture","content":"Put the test tube into a hot water bath and heat the mixture to at least $70^\\circ\\text{C}$ (or boil it). Heating allows Benedict's test to show its result.\n\nStating the water bath and heating earns the second **B1**.","highlights":[{"text":"biochemical test on the urine sample","location":"specification"}]},{"type":"text","order":3,"title":"Identify a positive result","content":"Start with Benedict's reagent, which is blue. If glucose is present, the heated mixture changes from blue to **green, yellow, orange, or brick-red**. A red precipitate (a solid formed in the liquid) is also a positive result.\n\nObserving and interpreting one of these changes earns the final **B1**: glucose is present in the urine.","highlights":[{"text":"determine if glucose is present","location":"specification"}]}]}],"generatedAt":"2026-07-22T07:34:43.073Z","modelVersion":"gpt-5.6-terra+diagrams-1","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"4edea0b9-2ea9-4c90-920d-5ebb4fa57b20","revisionId":"d17991f2-7246-4ac5-9ff3-35ad010f469c","questionNumber":null,"questionType":"LA","specification":"A student investigated fluid samples taken from three different regions of a kidney nephron (Region X, Region Y, and Region Z) to study selective reabsorption.","difficulty":3,"difficultyBand":"medium","totalMarks":4,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"954d894b-6387-43d0-b0fa-6c2f0d02fa2c","label":null,"content":"Describe how the student could use the equipment shown in Figure 1 to find out if these three fluid samples contain different concentrations of glucose.\n![Figure 1: Laboratory apparatus for biochemical testing. It includes three test tubes containing fluid samples, a bottle of Benedict's solution with a dropper pipette, a thermostatically controlled water bath, and a stopwatch.](https://assets.mathsgenie.co.uk/aqa-qb/a736fb2e-e583-498a-9ef0-4e7660eb6e56.png)","markscheme":"- Add a consistent / equal volume of Benedict's reagent to a consistent / equal volume of each of the fluid samples (Region X, Y, and Z) in separate test tubes B1\n- Heat the test tubes in the water bath at a high temperature (at least $70-80^\\circ\\text{C}$) for a set period of time (e.g. 5 minutes) B1\n- Observe and record the final color of each solution (or use the stopwatch to measure the time taken for the first color change to occur) B1\n- Compare the colors to estimate relative glucose concentration, where blue indicates no glucose, green/yellow indicates low concentration, and orange/brick-red indicates high concentration B1","marks":4,"order":0,"markingRubric":null,"explanation":{"methods":[{"id":"benedicts_test","label":"Benedict's test","steps":[{"type":"text","order":0,"title":"Set up fair volumes","content":"Use three separate test tubes, one for each fluid sample: Region X, Region Y and Region Z. Add the **same volume** of each sample, then add the **same volume** of Benedict’s reagent to each tube.\n\nKeeping these volumes equal makes this a fair comparison: any difference in colour can be linked to glucose concentration, rather than to using more liquid in one tube. This earns **B1**.","highlights":[{"text":"three fluid samples contain different concentrations of glucose","location":"specification"}]},{"type":"text","order":1,"title":"Heat for equal time","content":"Place all three tubes in the wat

Blood glucose control, diabetes and the urinary system

Question 13

Blood glucose control, diabetes and the urinary system Questions

Blood glucose control, diabetes and the urinary system

Question 13

Blood glucose control, diabetes and the urinary system Questions