Biology 11–12 · Year 12

Testing simulated urine for glucose and protein: evidence of diabetes and kidney damage

Module 8: Non-infectious Disease and Disorders (Homeostasis: glucose; Technologies and Disorders: loss of kidney function)

PracticalMedium risk

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

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The idea

When blood glucose rises above what the kidney tubules can reabsorb, glucose appears in urine, and protein in urine signals damaged filters, so simple tests on urine reveal failures of homeostasis.

Safety card

Medium riskA teacher supervises

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

Benedict's reagent contains copper(II) sulfate: low hazard at this concentration (the WJEC sheet, citing CLEAPSS) but irritating to eyes
Biuret reagent contains an alkali: irritant to corrosive
Hot water bath

Controls

Eye protection throughout; wash splashes off at once
Syringes for reagents; no pipetting by mouth
Tongs or test-tube holders at the water bath
Simulated samples only; no real urine or blood is ever collected or tested

Note

Benedict's and biuret reagents: NSW Department of Education Chemical Safety in Schools package (https://education.nsw.gov.au/content/dam/main-education/asset-management/chemical-safety/1._Section_1_-_General_information_for_all_staff.pdf) and RiskAssess (https://www.riskassess.com.au/).

What you need

Four simulated urine samples A to D, 30 mL each, made by the technician from water coloured with tea: A with protein (albumin powder) only, B with glucose only, C with neither, D with both (the WJEC design); never real urine
Glucose standards 0, 0.1, 0.5, 1.0 and 2.0 g per 100 mL, 10 mL each
Benedict's reagent; biuret reagent from a supplier; urinalysis test strips for glucose and protein (optional)
Water bath at 80 degrees Celsius; test tubes and rack; 5 mL syringes; 10 mL measuring cylinder; eye protection

How to do it

Test each glucose standard: 5 mL of standard and 5 mL of Benedict's reagent in the 80 degrees Celsius water bath for 5 minutes; line the tubes up as a colour scale.
Test 5 mL of each sample with 5 mL of Benedict's reagent in the same way and match its colour to the scale.
Test 5 mL of each sample with 2 mL of biuret reagent, shake gently and record the colour.
Confirm with test strips if available, reading them at the time the pack states.
Decide which sample came from a person with uncontrolled diabetes and which from a person with kidney damage, and explain using the renal threshold for glucose.
Draw the negative feedback loop for blood glucose, showing where insulin and glucagon act and where the loop fails in diabetes.

What you should see

Glucose standards give a colour sequence from blue (0) through green and yellow to orange and brick red as concentration rises; samples B and D change colour with Benedict's reagent and match a standard, while A and C stay blue. Biuret turns A and D violet and leaves B and C blue. Glucose normally appears in urine only when plasma glucose exceeds the renal threshold of about 10 mmol/L given by the patient.info clinical reference; 180 mg/dL of glucose is 9.99 mmol/L (computed with a molar mass of 180.16 g/mol). The learner knows it worked when each sample is identified the same way by both reagents and by the strips.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Glucose in urine means the kidneys are failing; it usually means blood glucose is above what healthy tubules can reabsorb.
Diabetes is caused by eating sugar alone; it is a failure of insulin production or response in the glucose feedback loop.
Protein should pass into urine like glucose; healthy glomeruli hold large proteins back, so protein in urine points to filter damage.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Biology Stage 6 Syllabus (2017), current: Year 11 taught to the end of 2026 and Year 12 to Term 3 2027BIO12-15 BIO11/12-5
Biology 11–12 Syllabus (2025), Year 11 focus area Cells to systems; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-11-02
Biology 11–12 Syllabus (2025), Year 11 Working scientifically; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-11WS-02 BI-11WS-03 BI-11WS-05
Australian Curriculum v9No Australian Curriculum v9 code is listed.

Sources

The pages the author read to write this activity.

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