What happens during Photosynthesis?
The equation for photosynthesis is:
carbon dioxide (6CO2) + water (6H2O) ------------------> glucose (C6H12O6) + oxygen (6O2)
- The green chemical chlorohyll absorbs light.
- The energy is used to rearrange the atoms of carbon dioxide and water.
- The products are glucose ( a sugar ) and oxygen ( a waste product ).
How do plants use the glucose?
- convert some of the Glucose into chemicals needed for growth, such as cellulose, protein and chlorophyll.
- convert some into starch for storage.
- use some in respiration to release energy.
Because it is insoluble Starch has little effect on the osmotic balance of cells. A high concentration of glucose causes water to be drawn into cells. Therefore starch is a better storage molecule than glucose.
Energy released in respiration is used to synthesise polymers such as:
- starch and celluse from glucose.
- Amino acids and then proteins from glucose and nitrates.
Plant roots absorb nitrates by active transport, a process that requires energy.
Variation in the rate of Photosynthesis.
The rate of photosynthesis may be limited by low.
- Carbon dioxide concentraton.
- Light intensity.
The amounts of carbon dioxide and oxygen exchanged over a 24 hour period vary. At compensation points the rate of photosynthesis and respiration balance. So there is no net movement of these gases between a plant and the surrounding atmosphere.
The rate of photosynthesis is limited by the factor that is in shortest supply.