Photosynthesis: In Depth: Dr.A

Question 1

Explain the LDR of PHOTOSYNTHESIS

Answer 1

1a) Photoionisation- PSII Chlorophyll (Pig is Chloro B) Absorbs LE from SUN and Excites Electrons & Leaves Chlorophyll into Stroma

1b) Photolysis- Occurs simultaneously with [1a] , H2O Absorbs LE and turns into:
H2O—-> 1/2O2 + 2H+ + 2e-
This occurs TWICE so one whole O2 molecule is produced, and e- returns to PSII so [1a] can repeat & 2H+ go to ATP-Synthase

2) e- Jumps across the Memb. onto ECP & passes down ETC, releasing Energy each jump, which is used to Actively Transport H+ into Membrane from Stroma—-> Conc. Grad.

3) Phtotoionisation [B]- e- Jumps from ETC to PSI Chlorophyll, (Pig is Chloro A), and Absorbs LE from sun & Excited e- which leave PSI back to Stroma, then Jumps onto ECP Ferredoxin and down ETC, then back to Stroma

4) Energy released from e- jumping from [3] used to Reduce NADP + e- —-> NADPH

5) H+ Diffuses out of Lumen (Chemiosmosis) via ATP-Synthase- allows for optimal pH to work

6) Photophosphorylation- ADP is Phosphorylised in Stroma

Products: NADPH + O2 + ATP