The part of photosynthesis that absorbs energy in the form of photons is called the "Light-Dependent Reactions" or "Light Reactions". Here's a step-by-step explanation:

1. The process begins when sunlight hits the leaf of a plant. The chlorophyll, a pigment in the chloroplasts of the plant, absorbs the light energy.

2. This energy is used to excite electrons in the chlorophyll. The excited electrons are then transferred to a series of proteins known as the electron transport chain.

3. As the electrons move along the chain, they release energy. This energy is used to pump hydrogen ions across the thylakoid membrane into the thylakoid space creating a concentration gradient.

4. The hydrogen ions then flow back across the membrane, down their concentration gradient, through a protein called ATP synthase. This flow of ions provides the energy needed for ATP synthase to convert ADP into ATP, the energy currency of the cell.

5. Meanwhile, the light energy also splits water molecules into oxygen, hydrogen ions, and electrons. The oxygen is released as a waste product, the electrons replace those lost by the chlorophyll, and the hydrogen ions contribute to the creation of a proton gradient.

6. The light-dependent reactions also produce NADPH, another energy-carrying molecule. The NADP+ molecule picks up the excited electron and a hydrogen ion to become NADPH.

7. The ATP and NADPH produced in the light-dependent reactions are then used in the next stage of photosynthesis, the light-independent reactions or the Calvin cycle, to produce glucose.

Question

The part of photosynthesis that absorbs energy in the form of photons is called the "Light-Dependent Reactions" or "Light Reactions". Here's a step-by-step explanation:

1. The process begins when sunlight hits the leaf of a plant. The chlorophyll, a pigment in the chloroplasts of the plant, absorbs the light energy.

2. This energy is used to excite electrons in the chlorophyll. The excited electrons are then transferred to a series of proteins known as the electron transport chain.

3. As the electrons move along the chain, they release energy. This energy is used to pump hydrogen ions across the thylakoid membrane into the thylakoid space creating a concentration gradient.

4. The hydrogen ions then flow back across the membrane, down their concentration gradient, through a protein called ATP synthase. This flow of ions provides the energy needed for ATP synthase to convert ADP into ATP, the energy currency of the cell.

5. Meanwhile, the light energy also splits water molecules into oxygen, hydrogen ions, and electrons. The oxygen is released as a waste product, the electrons replace those lost by the chlorophyll, and the hydrogen ions contribute to the creation of a proton gradient.

6. The light-dependent reactions also produce NADPH, another energy-carrying molecule. The NADP+ molecule picks up the excited electron and a hydrogen ion to become NADPH.

7. The ATP and NADPH produced in the light-dependent reactions are then used in the next stage of photosynthesis, the light-independent reactions or the Calvin cycle, to produce glucose.

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