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Question
How does the light-dependent reaction differ from the light-independent reaction? What are the end product and reactants in each? Where does each reaction occur within the chloroplast?
Solution
Light-dependent photosynthesis is called Hill reaction or Light reaction. The Light independent reactions are called the Biosynthetic phase.
| Light-dependent reaction | Light independent reaction |
| 1. It is called Hill reaction or Light reaction. | 1. It is called the Dark reaction or Biosynthetic pathway or the Calvin cycle. |
| 2. The reaction is carried out in Thylakoid membranes (Grana) of the chloroplast. | 2. This reaction is carried out in the stroma of the chloroplast. |
| 3. Photosynthetic pigments absorb the light energy and convert it into chemical energy ATP and NADPH2. | 3. CO2 is reduced into carbohydrates with the help of light-generated ATP and NADPH2. |
| 4. It is carried out in the presence of light. | 4. It is carried out in the absence of light. |
In the light-dependent reaction, the chlorophyll absorbs the light energy and converts it into chemical energy ATP and NADPH2. In the light-independent reaction, CO2 is reduced into carbohydrates with the help of light-generated ATP and NADPH2. The light-dependent reaction is carried out in the Grana of the chloroplast. The Light independent reaction is carried out in the stroma of the chloroplast.
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