Photosynthesis Flashcards
What are the key structures of the chloroplast?
- Thylakoids (contain chlorophyll, site of light-dependent reactions)
- Grana (stacks of thylakoids, increase surface area)
- Stroma (fluid-filled space, site of the Calvin Cycle)
- Double membrane (controls movement of substances)
Where do the light-dependent reactions occur?
- In the thylakoid membranes of the chloroplast.
What are the main steps of the light-dependent reactions?
- Photon absorption in Photosystem II (PSII)
- Photolysis of water
- Electron transport and ATP synthesis
- Photon absorption in Photosystem I (PSI)
- Formation of reduced NADP
- What happens during photolysis of water?
Water is split into H⁺ ions, electrons, and oxygen:
2H₂O → 4H⁺ + 4e⁻ + O₂
- O₂ is released as a waste product.
How is ATP produced in the light-dependent reactions?
✅ Through chemiosmosis, where H⁺ ions move through ATP synthase, generating ATP.
What is the role of NADP in the light-dependent stage?
- NADP is reduced to NADPH, which carries electrons to the Calvin Cycle.
What are the products of the light-dependent reactions?
ATP (energy for the Calvin Cycle)
NADPH (carries electrons to the Calvin Cycle)
O₂ (waste product released into the atmosphere)
Where do the light-independent reactions occur?
- In the stroma of the chloroplast.
What are the key steps of the Calvin Cycle?
- Carbon fixation – CO₂ combines with RuBP.
- GP is reduced to TP using ATP & NADPH.
- RuBP is regenerated using ATP.
What is the role of RuBisCO in the Calvin Cycle?
RuBisCO (Ribulose-1,5-bisphosphate carboxylase-oxygenase) fixes CO₂ by combining it with RuBP
How is Glycerate Phosphate converted to TP in the Calvin Cycle?
GP is reduced to TP using ATP and NADPH from the light-dependent stage.
What happens to Triose Phosphate in the Calvin Cycle?
Some TP is used to make glucose.
Most TP is recycled to regenerate RuBP.
How is RuBP regenerated in the Calvin Cycle?
Most TP molecules are used to regenerate RuBP, using ATP.
What are the main products of the Calvin Cycle?
Glucose – Used in respiration or stored as starch.
Regenerated RuBP – Keeps the cycle going.
What are the four main limiting factors of photosynthesis?
Light intensity
CO₂ concentration
Temperature
Water availability
How does CO₂ concentration affect photosynthesis?
Higher CO₂ increases the rate until RuBisCO becomes saturated.
How does water availability affect photosynthesis?
Less water → stomata close → less CO₂ uptake → lower photosynthesis rate.
How can chromatography be used to study photosynthesis?
Separates photosynthetic pigments.
Rf value = distance pigment moved ÷ distance solvent moved.
