Starch in leaves
To demonstrate the presence of starch in vegetable tissues.
What students learn
The science behind this experiment
The plant converts carbon dioxide from the air into oxygen and glucose by photosynthesis. Plants store glucose in long molecular chains called starch. Starch is synthesised and stored within chloroplasts and, in most species, is the primary storage form mobilised for translocation during the night.
Equipment used
- Spirit burner — 5514.10
- Tripod stand — 5533.10
- Wire gauze — 5534.25
- Beaker 250 ml — 1118.35
- Beaker 500 ml — 1118.50
- Petri dish — 1253.00
- Tweezers — 8261.30
- Tin foil
- Small plant
Chemicals and reagents
- Lugol's solution — R:21-22 S:24/25
- Ethanol — R:11 S:7-16
- Water
Safety notes
- Work in a fume cupboard or outdoors.
- Be careful handling the burner and hot glassware.
Questions for students
- Describe what happens to the leaf during each stage.
- Try to give an explanation.
What to expect
<p>Dipping the leaf in boiling water kills cells and will allow the chemicals to mix. Treating the leaf with alcohol extracts chlorophyll and gives a clearer result.</p><p>Lugol’s solution is a specific iodine reagent that points out the presence of starch turning its colour to blue.</p><p>The leaf part exposed to light made carried out photosynthesis regularly, producing glucose that is stored as starch.</p>
Disposal
Dispose of Lugol's solution into the acids and bases waste container.
Run this experiment in your classroom
This experiment is part of the ATP Mobile Lab — a self-contained laboratory that turns an ordinary classroom into a working science lab, with over 200 experiments in physics, chemistry, biology, robotics and engineering. Gali, the AI tutor built into ATP Connect, guides students through each step and answers their questions at the bench.
See the Mobile LabTalk to our team