photosynthesis Flashcards
describe the LDR
photo ionisation
-chlorophyll absorbs light
-excites electrons to a higher energy level
-electrons lost from chlorophyll
-electrons pass down electron transfer chain by redox reactions
photophosphorylation
-energy released is used to pump protons (H+) across thylakoid membrane, into thylakoid space forming proton electrochemical gradient
-protons diffuse down electrochemical gradient through ATP synthase, catalysing ADP + Pi -> ATP
photolysis
-light splits 2H20 -> 4H+ + 4e- +O2
-e- replace electrons lost in chlorophyll
-H+ and NADP act as an electron acceptor for electron at end of ETTC forming NADPH (reduced NADP)
describe the LIR
carbon fixation
-rubisco catalyses CO2 combining with RUBP
reduction
-splits into 2x GP
-GP is reduced using NADPH TO triose phosphate (uses energy from ATP)
triose phosphate can be converted into organic substances
regeneration
-most triose phosphate converted into RUBP
where does the ldr occur
granum
where does the lir occur
stroma
what are the limiting factors of photosynthesis
temperature
carbon dioxide concentration
light intensity
the highest rate of photosynthesis is when all factors are at
the optimum level
how may commercial farming control limiting factors
artificial light to increase light intensity
blinds if light intensity is too high
co2 levels increased by burning fossil fuels
heaters can raise temp
describe the effect of introducing a herbicide on the electron transport chain
reduced transfer of protons across thylakoid membrane
so less atp produced
so less reduced nadp produced
so light independent reaction is stopped/slowed
in plants, atp is produced in the light dependant reaction
suggest why this is not a plants only source of atp
plants dont photosynthesise in the dark
not all the parts of the plant photosynthesise ( roots)
plants require more atp then is produced in the light dependant reaction
atp used in active transport
