Photosynthesis Reaction Stages 3

Question 1

Which molecule acts as the mobile electron carrier between Photosystem II and the cytochrome b6f complex?

Accepted Answer

Plastoquinone

Answer

Plastoquinone (PQ) is a lipid-soluble molecule that picks up electrons and protons from PSII and delivers them to the cytochrome b6f complex.

Question 2

In the light-independent reactions, what is the immediate product after CO2 is fixed by RuBisCO onto RuBP?

Accepted Answer

Two molecules of 3-phosphoglycerate

Answer

RuBisCO catalyzes the addition of CO2 to RuBP, forming an unstable 6-carbon intermediate that immediately splits into two 3-phosphoglycerate (3-PGA) molecules.

Question 3

Which wavelengths of light are LEAST effectively absorbed by chlorophyll a?

Accepted Answer

Green (500-560 nm)

Answer

Chlorophyll a reflects green wavelengths, making it the least efficient at absorbing green light and giving plants their green color.

Question 4

What structural feature of the chloroplast maximizes the surface area for the light reactions?

Accepted Answer

The grana stacks

Answer

Grana are stacks of thylakoid discs that greatly increase membrane surface area, packing more photosystems into a small volume.

Question 5

How many ATPs and NADPHs does the Calvin cycle require to reduce three CO2 molecules to one G3P?

Accepted Answer

9 ATP and 6 NADPH

Answer

Three turns of the Calvin cycle (fixing 3 CO2) require 9 ATP and 6 NADPH to produce one net G3P molecule.

Photosynthesis Practice Test

Photosynthesis Practice Test

Photosynthesis Reaction Stages 3