Photosynthesis Energy Conversion 2

Question 1

What is the primary role of the antenna complex in the light-harvesting stage of photosynthesis?

Accepted Answer

To absorb photons and funnel energy to the reaction center

Answer

Antenna complexes contain pigment molecules that absorb light and transfer the excitation energy to the reaction center via resonance energy transfer.

Question 2

During the light-dependent reactions, which molecule acts as the final electron acceptor in the electron transport chain?

Accepted Answer

NADP+

Answer

NADP+ accepts two electrons and one proton at the end of the electron transport chain to become NADPH, which carries reducing power to the Calvin cycle.

Question 3

How does cyclic electron flow differ from non-cyclic electron flow in terms of products?

Accepted Answer

Cyclic produces only ATP; non-cyclic produces both ATP and NADPH

Answer

Cyclic electron flow recycles electrons through PSI back to the electron transport chain, generating ATP without producing NADPH or releasing O2.

Question 4

What is the approximate energy (in eV) of a visible-light photon that drives Photosystem II?

Accepted Answer

1.8 eV

Answer

Visible photons carry roughly 1.8–3.1 eV, and P680 in PSII is excited by red photons near 680 nm, corresponding to about 1.8 eV.

Question 5

Which process directly uses the proton gradient across the thylakoid membrane to synthesize ATP?

Accepted Answer

Chemiosmosis through ATP synthase

Answer

Chemiosmosis drives H+ ions through ATP synthase (a.k.a. CF0-CF1 complex) down their concentration gradient, powering ATP synthesis in the chloroplast.

Photosynthesis Practice Test

Photosynthesis Practice Test

Photosynthesis Energy Conversion 2