L6/7 Photosynthesis Flashcards
What are the main products of the light reactions?
ATP, NADPH, and O2.
What is the role of NADPH in photosynthesis?
It provides reducing power for the dark reactions to convert CO2 into carbohydrates.
Which pigments extend the light capture range in photosynthesis?
Antenna pigments like carotenoids, phycocyanin, and phycoerythrin.
What is the main pigment in photosynthesis, and what metal does it contain?
Chlorophyll; it contains magnesium (Mg2+).
What wavelength of light does PSII absorb?
680 nm (P680).
What connects PSII and PSI in the electron transport chain?
The cytochrome bf complex.
What generates the proton gradient in light reactions?
Electron transport through the Z-Scheme.
What is photophosphorylation?
ATP synthesis dependent on light-driven proton gradient.
What is the purpose of cyclic electron flow?
To produce additional ATP without generating NADPH.
How does cyclic electron flow contribute to the proton gradient?
Electrons are recycled to the PQ pool, increasing the proton motive force.
What is RuBisCO, and why is it important?
RuBisCO is an enzyme critical for carbon fixation in photosynthesis. It catalyses the reaction between CO2 and RuBP to form PGA.
How do C4 and CAM photosynthesis differ in overcoming RuBisCO limitations?
C4 uses spatial separation (mesophyll and bundle sheath cells), while CAM uses temporal separation (night and day fixation).
Why is photorespiration a problem for C3 plants?
Photorespiration occurs when RuBisCO fixes O2 instead of CO2, producing toxic by-products and wasting ATP and NADH.
What is the role of malate in C4 and CAM photosynthesis?
Malate acts as a carrier of CO2, delivering it to RuBisCO for refixation while minimising oxygenation.
Which major crops utilise C4 and CAM pathways?
C4: Maize; CAM: Pineapple.
