5.1 PHOTOSYNTHESIS Flashcards
What is the equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2
What are the stages of photosynthesis? (2)
- Light-dependent reaction.
2. Light-independent reaction.
What is step 1 of the light-dependent reaction?
Chlorophyll absorbs light at photosystem two, where electrons are excited to a higher energy level, from the thylakoid space to the stroma.
What is step 2 of the light-dependent reaction?
The electron carriers gain the excited electrons.
What is step 3 of the light-dependent reaction?
The excitation of electrons causes photolysis.
What is photolysis?
The splitting of 2 water molecules into 2 oxygen gas molecules, 4 H⁺ and 4e¯.
(occurs in thylakoid space)
- H⁺ move from thylakoid space to the stroma.
- The electrons are taken up by the chlorophyll at PS1.
- Oxygen is used in respiration or diffuses out of the stomata.
What is step 4 of the light-dependent reaction?
The excited electrons travel down ETCs, releasing energy so that H⁺ protons (from photolysis) can move from the stroma back to the thylakoid space.
What is step 5 of the light-dependent reaction?
At the end of the ETC, the electrons reach photosystem 1.
What is step 6 of the light-dependent reaction?
Light strikes at PS1 and the electrons are excited again.
What is step 7 of the light-dependent reaction?
Electrons travel through another ETC, and at the end, they join with NADP to form reduced NADPH.
What is step 8 of the light-dependent reaction?
From step 4 there is now an excess of H⁺ in the thylakoid space. H⁺ diffused through the ATP synthase channel into the stroma and formed ATP.
What is the yield of the light-dependent reaction?
- NADPH
- ATP
What is the light-independent reaction called?
The Calvin cycle
Where does the Calvin cycle occur?
In the stroma of chloroplasts.
What is step 1 of the Calvin cycle?
Carbon dioxide reacts with RuBP (5C) to form 2 molecules of GP (2 x 6C). This reaction is catalysed by the rubisco enzyme.
