O-Level Biology Osmosis Practical Guide: Potato and Visking Tubing
04 Nov 2025, 00:00 Z
Want small-group support? Browse our O-Level Biology Tuition hub. Not sure which level to start with? Visit Biology Tuition Singapore.
Looking for the full lab practical series? Visit the O-Level Biology Practicals.
Practical course completion-record note
For practical, lab, and experiment courses, Eclat Institute maintains centre-held attendance records and may also issue an internal attendance or completion document based on participation and internal assessment.
- For SEAB private-candidate declarations, the key evidence is the centre's attendance or completion record, not a government-issued certificate.
- This is an internal centre-issued certificate, not an MOE/SEAB qualification or accreditation.
- Recognition (if any) is determined by the receiving school, institution, or employer.
- For SEAB private candidates taking science practical papers, SEAB states you should either have taken the subject before or attend a practical course and complete it before the practical paper date.
View our sample completion document (Current sample layout (design may be refined over time))
Planning a revision session? Use our study places near me map to find libraries, community study rooms, and late-night spots.
Q: What does this O-Level Biology osmosis practical guide cover?
A: It shows you how to run the Paper 3 potato and Visking tubing osmosis experiments, calculate percentage change, and evaluate the isotonic point properly.
TL;DR
Osmosis questions dominate the water-relations strand of the 6093 syllabus and almost always appear as paired setups (dialysis tubing plus plant tissue).
Nail your mass/length measurements, present percentage change tables with sig. figs, and give ACE commentary that links the gradient direction to cell turgor or plasmolysis.
Keep a bank of fair-test controls and improvement statements so you can answer every modification prompt.
Use this page after the broad O-Level Biology practical guide if you want the full Paper 3 context first.
Revisit the Full Experiment Bank
Pair this osmosis routine with the rest of our O-Level Biology Experiments collection so Paper 3 revision covers every standard skill block.
1 | Link back to syllabus language
- Section 2 of the syllabus expects candidates to explain osmosis in terms of water potential and semi-permeable membranes; Paper 3 enforces this with quantitative tasks (SEAB 2026 syllabus, PDF).
- Typical objectives examined:
- Planning (P): selecting appropriate solute concentrations, controlling temperature, ensuring equal surface area or volume.
- MMO: accurate weighing to 0.01 g, measuring lengths with a mm ruler, timing immersion periods.
- PDO: calculating percentage mass/length change, plotting graphs with labelled axes and units.
- ACE: comparing gradients, interpreting curves (e.g. identifying isotonic point), evaluating experimental design.
2 | Parallel setups to rehearse
A. Visking tubing sugar-osmosis test
- Fill dialysis tubing with 10 cm³ of 0.5 mol dm⁻³ sucrose solution, tie securely with cotton string.
- Suspend in a beaker containing 200 cm³ of distilled water; leave for 20 minutes.
- Use a syringe to collect the tubing contents at the end and record final volume/mass.
- Optional modification: reverse the gradient (distilled water inside, sucrose outside) to observe water inflow.
B. Potato strip or disc experiment
- Cut potato cylinders using a cork borer; trim to 5.0 cm using a sharp scalpel on a tile.
