Photosynthesis

Question 1

Light dependent stage

Answer 1

Chlorophyll absorbs light energy
Excites electrons in chlorophyll
Electrons move along electron transfer chain
Energy from electrons released
Energy used to transport H+ ions into thylakoid space H+ ions diffuse through ATP synthase to make ATP ADP and Pi condense to form ATP
H+ ions combine with NADP to form NADPH

Photolysis of water produces protons, electrons and oxygen
NADP reduced by electrons and protons
Oxygen released as a waste gas

Question 2

Light independent stage

Answer 2

Light independent reaction fixes CO2
CO2 fixed to ribulose bisphosphate.
to make 2 molecules of glycerate-3-phosphate.
The enzyme rubisco catalyses this reaction.
Glycerate-3-phosphate becomes reduced.
to form 2 molecules of triose phosphate
using NADPH from the light dependent reaction
using ATP from the light dependent reaction
5/6 of the triose phosphate is converted into ribulose bisphosphate.
1/6 of the triose phosphate is converted into organic substances eg glucose.