Photosynthesis Light Reactions 2

Question 1

Which pigment is primarily responsible for absorbing light energy in the light reactions?

Accepted Answer

Chlorophyll a

Answer

Chlorophyll a is the primary photosynthetic pigment that directly participates in the light reactions by absorbing red and blue-violet light.

Question 2

What is the role of the oxygen-evolving complex (OEC) in the light reactions?

Accepted Answer

It splits water molecules to release oxygen

Answer

The oxygen-evolving complex (also called the water-splitting complex) oxidizes water molecules, releasing O2, protons, and electrons to replenish Photosystem II.

Question 3

How many photons of light are required to release one molecule of O2 during the light reactions?

Accepted Answer

8

Answer

Splitting two water molecules to release one O2 requires 4 electrons, each needing 2 photons (one at PSII, one at PSI), totaling 8 photons.

Question 4

What happens to the electrons at the P700 reaction center when it absorbs light?

Accepted Answer

They are excited to a higher energy level and passed to ferredoxin

Answer

When P700 absorbs light, its electrons are excited and transferred to the primary acceptor A0, ultimately reaching ferredoxin.

Question 5

Which statement correctly describes the Z-scheme of the light reactions?

Accepted Answer

Electrons flow from water through PSII, the electron transport chain, PSI, and finally to NADP+

Answer

The Z-scheme describes the noncyclic electron flow from water → PSII → ETC → PSI → NADP+, named for the Z-shape of the energy diagram.

Photosynthesis Practice Test

Photosynthesis Practice Test

Photosynthesis Light Reactions 2