BioInteractive Light Reactions of Photosynthesis 3

Question 1

What is cyclic electron flow in photosynthesis?

Accepted Answer

Electrons from Photosystem I cycle back to the cytochrome b6f complex to generate extra ATP

Answer

In cyclic electron flow, electrons from Photosystem I return to cytochrome b6f, building the proton gradient to make extra ATP without producing NADPH.

Question 2

Which molecule connects the two photosystems by carrying electrons from PSI to PSII?

Accepted Answer

Plastocyanin

Answer

Plastocyanin is a copper-containing protein that transfers electrons from cytochrome b6f to Photosystem I.

Question 3

What drives the rotation of ATP synthase in chloroplasts?

Accepted Answer

Flow of H+ ions from thylakoid lumen to stroma

Answer

The movement of protons down their concentration gradient through ATP synthase drives the rotation that synthesizes ATP.

Question 4

What is the correct sequence of electron flow in the non-cyclic light reactions?

Accepted Answer

H2O → PSII → PQ → Cyt b6f → PC → PSI → Fd → NADPH

Answer

Non-cyclic electron flow moves electrons from water through PSII, the cytochrome complex, PSI, ferredoxin, and finally to NADP+ to form NADPH.

Question 5

What is the primary pigment in Photosystem II reaction centers?

Accepted Answer

Chlorophyll a (P680)

Answer

The reaction center of Photosystem II contains chlorophyll a molecules with peak absorption at 680 nm (P680).

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive Light Reactions of Photosynthesis 3