Photosynthesis Light Reactions
Learning Objective
I can describe how light energy is converted into chemical energy during the light reactions of photosynthesis.
Key Concepts
In the light-dependent reactions, chlorophyll in photosystem II absorbs sunlight, causing electrons to become excited and flow through the thylakoid membrane.
As electrons move through the thylakoid membrane, protein pumps pull hydrogen ions into the thylakoid, creating a high concentration, while water molecules are broken down to replenish electrons in photosystem II and release oxygen.
Sunlight also strikes photosystem I, exciting its electrons, and together with electrons from photosystem II, they power the creation of NADPH, a hydrogen carrier, and the diffusion of hydrogen ions through ATP synthase to produce ATP.
Practice Questions
This lesson includes 12 practice questions to reinforce learning.
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1. What are the initial reactants required for the light-dependent reactions of photosynthesis, as described in the video?
2. In the light-dependent reactions, light energy is used to excite electrons. What molecule initially captures this light energy?
3. List the four protein complexes found in the thylakoid membrane that are involved in the light-dependent reactions.
...and 9 more questions
Educational Video
Photosynthesis (in detail)
Beverly Biology