(3) A - Photosynthesis LDR Flashcards
LDR purpose
Capture light to;
- Add Pi to ADP to make ATP
- Photolysis; split H20 into H+ions (protons) & OH- ions
Reactants for LDR
4 x ☀️ photons
H20
Products for LDR
02 ; for plant resp
Diffused out leaf into air
ATP - LIR
Reduced NADP - LIR
H: combines w/ PS1 e- ; H made
Combines w/ NADP reduced NADP made
Oxidation
Gain 02
Lose H+ Lose Es
Lose energy
Combine w/ 02
The making of ATP
Chlorophyll absorbs ☀️
Boosts energy of pair of electrons; within chlorophyll mol excited to higher energy level
Electrons so excited they leave!
Taken up by electron carrier
Chlorophyll mol is OXIDISED (lost electrons)
Electron carrier is REDUCED (gain electrons)
Electrons pass along EC in series of O-R reactions
ECs form an ETC in thylakoid
Each carrier = lower energy level = energy lost at each stage
Energy combines w/ Pi & ADP to make ATP
Reduction
-02
+ H
+ E
Needs energy in
LDR takes place
Thylakoid of chloroplast
Thylakoids discs structures Stacked in Grana
Photolysis
Splitting of water by light;
2H20 -> 4H+ + 4e- + 02
Loss of electrons light strikes chlorophyll molecule
Hydrogen ions; taken up by EC ; NADP
NADP become reduced
Reduced NADP enters LIR
Electrons from Chlorophyll also enter LIR
NADP is v important
Reaction 1
☀️ absorbed by PS2
2 x Chlorophyll electrons excited to + energy level & leave
Taken up by ea
C : oxidised EA : reduced
Reaction 2
☀️ absorbed by PS1
2 x Chlorophyll electrons excited to + energy level & leave
Taken up by ea
C : oxidised EA : reduced
Reaction 3
PS1 electrons replaced
Excited Es PS2 passed down chain of ECP; series of O-R reactions
Energy lost by electrons
Each ECP is @ lower energy level; energy is lost as electrons
Reaction 3 (b)
Energy lost ; combines ADP & Pi = ATP made ; !!!!
And,
Electrons reach PS1 reduce chlorophyll & earlier electrons are replaced
LDR (4)
Replace electrons from PS2 chlorophyll
Photolysis;
2 H20 + 4 H+ Protons + 4e- + 02
Photolysis of PS2
Only PS2 photolysised
Takes place x 2 ; for 1 x 02
