non-cyclic photophosphoryation

Question 1

1st stage of the ETC in photosynthesis

Answer 1

light energy is absorbed by the PSII which excites electrons in the chlorophyll, the electrons move to a higher energy level. these high energy electrons are released form the chlorophyll and move down the ETC to the PSI

Question 2

2nd stage of ETC in photosynthesis

Answer 2

as the excited electrons leave the PSII they must replaced so photolysis takes place to split water into protons, electrons and oxygen

Question 3

3rd stage of ETC in photosynthesis

Answer 3

excited electrons lose energy as they move down the ETC, this energy is used to transport protons into the thylakoid so that they have a higher concentration of protons than the stroma, this creates a concentration gradient of protons. the protons move into the stroma down their concentration gradient via the enzyme ATP synthase which is embedded in the thylakoid membrane, the energy from this movement is used to add a phospate to a ADP to form ATP.

Question 4

4th stage of ETC in photosynthesis

Answer 4

light energy is absorbed by PSI which excites electrons to an even higher level which means theyre transferred to NADP along with a proton from the stroma to form reduced NADP

Question 5

why is cyclic photophosphorylation called ‘cyclic’

Answer 5

because the electrons from the chlorophyll molecule arent passed onto NADP, but are passed back to PSI via electron carriers, this means the electrons are recycled in the system.

Question 6

what does cyclic photophosphoryaltion produce

Answer 6

only small bits of ATP.