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Briefly summarize the process of photosynthesis starting from the light dependent energy.

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lehcir | Student | Valedictorian

Posted October 30, 2012 at 7:27 PM via web

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Briefly summarize the process of photosynthesis starting from the light dependent energy.

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jerichorayel | College Teacher | (Level 1) Senior Educator

Posted October 31, 2012 at 8:54 AM (Answer #1)

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6CO2 + 6H2O --------------> C6H12O6 + 6O2
                    sunlight energy
Photosynthesis can be summarized in the following steps.
1. In plants, photosynthesis occurs primarily in the leaves. the leaves is the part where the raw materials can be gathered together. Carbon dioxide and oxygen can enter and exit the leaves through a specialized cells called stomata. Water can be delivered through the vascular systems of the plant. And lastly, sunlight car being stored in the green pigment called chlorophyll which will further be used to excite the electrons.
2. There are two main events in photosynthesis: Light dependent or light independent reactions. 
     Light dependent -> light is trapped to form an ATP and NADPH,
                              an energy-giving molecules
     Light independent -> ATP is used to convert CO2 into glucose.
3. Light dependent (light reaction) reaction starts as the light energy that is absorbed splits a water molecule producing Oxygen and Hydronium ions and 2 electrons.
 H2O + light energy ---> ½ O2 + 2H+ + 2 electrons

4. Chlorophyll  (and other pigments) form the antenna complex that that transfers light energy that further transfer the excited electrons. The excited electrons leave the site via electron acceptors.
5. The excited electrons from step 3 will be transferred to the photosystem I to reduce p680. This step will produce 2 moles of ATP molecules.
6. The two electrons will be transferred again into the photosystem II in order to produce 2 moles of NADPH. 
7. ATP and NADPH will now enter the light independent reaction (dark reaction). The Dark reaction happens in the stroma of the chloroplasts. This reactions is called the Calvin cycle. In this reaction, CO2 is converted to sugar using the ATP and NADPH derived from the light reaction.

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