Biology 6.10: photosynthesis 2010

1. Photosynthesis consists of two stages; there are light reaction and dark reaction.

2. Light reaction happens in grana.

3. The chlorophyll in grana will absorb the light energy and this excites the electrons of the

chlorophyll to a higher level of energy.

4. At the same time, photolysis of water happens in which water molecules splited into hydrogen

ions (H+) and hydroxyl ions (OH-).

5. The hydrogen ions (H+) will receive electron from the chlorophyll and become hydrogen

atom. This hydrogen atom will used in dark reaction later.

6. Hydroxyl ions will donate the electron to the chlorophyll and become hydroxyl group.

7. After a series of reaction, the hydroxyl group will become oxygen and water.

8. In dark reaction, which is also called Calvin cycle. The hydrogen atom from the light reaction

will use to fix with carbon dioxide and form glucose and water.

9. We need 6 molecules of CH2O to form a molecule of glucose.

10. Condensation of glucose will form starch.

judy/bio/note/4A/2010