Chapter summary
Four statements, one equation, four experiments and four words.
The chapter in four points
- In photosynthesis, green plants convert solar energy into chemical energy.
- The factors sunlight, water, carbon dioxide and chlorophyll are essential for photosynthesis.
- In photosynthesis glucose is produced as the main product and oxygen gas as the by-product.
- As its global importance: supplying food directly or indirectly to all living things, keeping the CO2 and O2 composition of the atmosphere balanced, and maintaining the carbon cycle.
The balanced equation
6CO2(g) + 6H2O(l) → C6H12O6(s) + 6O2(g)
Above the arrow: light. Below the arrow: chlorophyll.
The four experiments, together
| Activity | What was changed | The control | What it showed |
|---|---|---|---|
| 2.3 | Light removed from part of a leaf, with black polythene | A leaf under colourless polythene | Sunlight is necessary |
| 2.4 | Carbon dioxide removed from the air round a leaf, with KOH | An identical leaf bagged with water | Carbon dioxide is necessary |
| 2.5 | Chlorophyll absent in part of a leaf, naturally | The green part of the same leaf | Chlorophyll is necessary |
| 2.6 | Nothing removed — a product was collected instead | The tube began completely full of water | Oxygen is produced |
Terms introduced in this chapter
| Sinhala | English |
|---|---|
| ප්රභාසංශ්ලේෂණය | Photosynthesis |
| හරිතලව | Chloroplasts |
| හරිතපුද | Chlorophyll |
| ජලරුහ ශාක | Aquatic plants |
What this chapter actually added
Grade 10 told you photosynthesis happens and gave you the equation. This chapter showed you the pipes that carry the raw materials in and the food out, and then took the equation apart and proved it one term at a time. Knowing a thing is true and knowing how anyone found out are different kinds of knowing, and the second is the one that makes you able to check.