photosynthesis

Question 1

what is photosynthesis

Answer 1

the use of radian sunlight energy to convert simple inorganic molecules into larger organic ones

Question 2

what are organisms called that photosynthesises

Answer 2

photoautotroph which incluse plants, some prokaryotes and some protoctists

Question 3

what is the equation of photosynthesis

Answer 3

6CO2+6H2O -> C6H12O6 + 6O2

carbon dioxide + water -> Glucose +Oxygen

Question 4

where does photosynthesis occur

Answer 4

in the choloroplasts and require the pigment cholorphyll found on the thylakoid membrane

Question 5

where does photosynthesis occur

Answer 5

in two parts, light dependent reaction on the thylakoid membrane. light independent reaction in the stroma

Question 6

what is the light dependent reaction

Answer 6

A photon of light hits a molecule of cholorophyll on the thylakoid membrane
the cholorophyll molecule is photoexcited and elctrons are lost (oxidation reaction)
these electrons pass though a series of electron carriers in the thylakoid membrane
these provide energy for the pumping of hydrogen ions from the stroma across the thylakoid membrane into the thylakoid space.
this sets up an electrochemical gradient, hydrogen ions pass down the gradient through ATP synthetase so producing ATP from ATP and Pi.
this is photophosphorylation

Question 7

what does photolysis mean

Answer 7

reducing or ‘recharging’of the cholorophyll
some water which eneters the plant undergoes photolysis in teh thylakoid space. light splits the water molecules into H ions and electrons and oxygen.
the electrons replace those lsot from the chlorophyll - reduction reaction
the oxygen is given off as a by-product
the H ions reduced coenzyme NADP in the stroma to NADPH2 which is a higher energy molecule

Question 8

what is the light independent reaction

Answer 8

occurs in stroma, which contains various enyzymes including rubisco.
it also contains a pentose called ribulose biphosphate (RuBP). carbon dioxide from air diffuses into stroma via stomatal pores in the leave. the co2 combines with the RuBP a reaction catalysed by RUBSICO
an unstable 6C compound briefly forms but splits into two 3C molecules of glycerate-3-phosphate
ATP from the light dependent phase then phosphorylates the 2 GP molecules
they are then reduced by NADPH2 from the light dependent phase
2 molecules of triose phosphate have no been produced and the NADPH2 is oxidised back to NADP.
to maintain the cycle 5/6ths of the triose phosphate enters ATP-driven reactinos to regenerate RuBP. 1/6th of the triose phosphate is built up into starch via glucose phosphate via condensation reactions