8.3 Photosynthesis Flashcards
Where is the light dependent reaction?
In the thylakoid membrane.
Outline how ATP is made during the light dependent reaction.
Chlorophyll in photosystm II absorbs light, which excites free electrons inside. 2 electrons then pass along a series of carriers. Their energy is used to move protons from the stroma into the thylakoid space, creating a concentration gradient. Those protons later move via chemiosmosis through the ATP synthase back to the stroma, making ATP. Then the electrons move on to Photosystem I to get re-energised.
What is cyclic phosphorilation?
The re-energised electrons go to a protein that moves H+ ions across the membrane again.
What is non-cyclic phosphorilation?
The electrons move to a protein, where they reduce NADP+ to NADPH.
How are the electrons replaced in non-cyclic phosphorilation?
The electrons lost by photosystem I are replaced by electrons from photosystem II. The electrons lost by photosystem II are replaced by electrons coming from water that went through photolysis, where Water –> Oxygen (waste product) + electrons + protons
Where does the light independent reaction take place?
In the stroma
Outline the light independent reaction/ Calvin Cycle.
RuBP and CO2 react, catalysed by rubisco, to create G3P.
The NADPH from the light dependent reaction provides electrons to reduce G3P to from triose phosphate (ATP needed for this reaction). 1/6 triose phosphates leaves the cycle to become sucrose, starch… (So every 3 cycles, as there are 2 triose phosphates/ 1 RuBP per cycle. )The other triose phosphates use ATP to become RuBP again.
How is the light independent reaction dependent on the light dependent reaction.
The ATP and NADPH are used in the light independent reaction and provided by the light dependent reaction.
