Question

Which statement regarding the light reactions is true? A Photoexcited electrons pass from photosystem I to photosystem II.B Glucose is a product of the light reactions.C Electrons are supplied to chlorophyll P680 as it reduces the primary electron acceptor.D Electrons "falling" down the electron transport chain are deposited on ADP to form ATP.

Answer 1

In the light reactions, b. photoexcited electrons pass from photosystem I to photosystem II.

Step-by-step explanation:

The true statement regarding the light reactions is that the Photoexcited electrons pass from photosystem I to photosystem II. When photons strike photosystem II, pigments pass the light energy to chlorophyll a molecule that generally excites an electron, which is then passed to the electron transport chain. During this step of photosynthesis, the molecule ATP and the reduced electron carrier NADPH are produced that can be used for further reactions.

The cytochrome complex transfers protons across the thylakoid membrane and transfers electrons from PS-II to PS-I. The products of the light-dependent reactions, including ATP and NADPH, are used to power the Calvin cycle to produce glucose.

Answer 2

The correct answer is: C Electrons are supplied to chlorophyll P680 as it reduces the primary electron acceptor

Light dependent reactions are part of the photosynthesis and they occur in the thylakoid membranes of chloroplasts. During this step of photosynthesis, molecule ATP and the reduced electron carrier NADPH are produced that can be used for the further reactions. The main role in light dependent reaction are photosystems (complexes of proteins and light-absorbing molecules-pigments):

Photosystem I (PSI)- pair of chlorophyll P700

Photosystem II (PSII) - pair of chlorophyll P680

Energy is transferred from pigment to pigment in PSII to P680, where an electron is boosted to a high energy level. That high-energy electron is then passed to an acceptor molecule and replaced with an electron from water.