Integrated Science · Unit 7 · Practicals 7.5–7.7
Photosynthesis laboratory
Follow a leaf from the plant to the starch test. In student mode, answer the questions at each step to continue.
- 1 Destarch
- 2 Check starch
- 3 Conditions
- 4 Expose
- 5 Starch test
The laboratory bench
Detailed apparatus view
What makes this a fair test?
Use comparable destarched plants, change one condition, and keep temperature and exposure time alike. For the light test, cover both sides of the middle strip with clipped aluminium foil or opaque black paper, leaving the tip and base exposed. Remove the covering after exposure and before the starch test. A variegated leaf compares green and cream regions within the same leaf. Withholding water for long enough can kill a plant. The no-water scene compresses this process; use a fresh watered plant to continue the starch experiment.
Advanced mode uses an illustrative limiting-factor model: increasing one resource cannot replace another missing resource. Green leaf area changes the area that can form starch. The sliders are relative settings; the iodine test is qualitative and cannot measure an exact photosynthesis rate. See SAPS — factors affecting photosynthesis.
Technique reference: Practical Biology — testing leaves for starch.