Year 13 - Photosynthesis

Question 1

Describe the LDR ​(photosynthesis)

Answer 1

1. Chlorophyll absorbs light energy​
2. Excites electrons to higher energy level ​
3. electrons lost from chlorophyll. ​
4. Electrons pass down electron transfer chain by redox reactions​
5. Energy released is used to pump protons (H+) across thylakoid membrane, into thylakoid, forming proton electrochemical gradient. ​
6. Protons diffuse down electrochemical gradient, through ATP synthase, catalysing ADP + Pi -> ATP. ​
7. Light splits 2H2O -> 4H+ + 4e- + O2 ​
8. e- replace electrons in chlorophyll​
9. H+ and NADP act as an electron acceptor for electron at end of ETC forming NADPH (reduced NADP).

Question 2

Describe the LIR ​(photosynthesis)

Answer 2

1.Rubisco catalyses CO2 combining with RUBP ​
2. Splits into 2 x GP​
3. GP is reduced using NADPH to​ triose phosphate ​
4. This uses energy from ATP.​
5. triose phosphate can be converted glucose (/organic substances etc)​
6. most triose phosphate converted back to RUBP.