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What is photosynthesis?
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy, producing glucose and oxygen from carbon dioxide and water.
Where do the light reactions occur?
Light reactions occur in the thylakoid membranes of chloroplasts and produce ATP and NADPH for the Calvin cycle.
What are photosystems?
Photosystems are protein-pigment complexes that capture light energy to drive electron transport in the light reactions of photosynthesis.
What is the function of Photosystem II (PSII)?
PSII absorbs light to split water molecules, releasing oxygen, protons, and electrons, and creating a proton gradient for ATP synthesis.
What is the function of Photosystem I (PSI)?
PSI absorbs light to produce NADPH by transferring excited electrons to ferredoxin and NADP+ reductase.
How do Photosystem II and Photosystem I work together?
Electrons from PSII are transferred through the electron transport chain to PSI, and the energy produced creates ATP and NADPH for the Calvin cycle.
What are the inputs and outputs of the light reactions?
Inputs: Light energy, water, NADP+, ADP + Pi.
Outputs: Oxygen, NADPH, ATP.
Where do the light-independent reactions (Calvin cycle) occur?
The Calvin cycle occurs in the stroma of chloroplasts, converting carbon dioxide into glucose using ATP and NADPH.
What is carbon fixation in the Calvin cycle?
Carbon fixation is the process where carbon dioxide is fixed into a stable intermediate by the enzyme RuBisCO.
What is photorespiration?
Photorespiration occurs when RuBisCO fixes oxygen instead of CO₂, reducing the efficiency of photosynthesis in C3 plants.
What adaptations do C4 and CAM plants have to reduce photorespiration?
C4 plants use PEP carboxylase to initially fix CO₂, while CAM plants fix CO₂ at night to conserve water.
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