biochemistry exam 3 sidequest Photosynthesis

Photosynthesis

The P680 molecule is activated by light at 680 nm, producing a high-energy state, P680*. P680* loses an electron which eventually makes its way to plastocyanin. How is the electron replaced?

by interaction with plastocyanin

directly from water

indirectly from water via the manganese complex

by interaction with cytochrome f

indirectly from water via the manganese complex

The P700+ molecule that is formed also is electron deficient. From where does the electron come that restores P700 to its ground state?

Ferredoxin

Plastocyanin

Water

NADPH

Plastocyanin

How many photons of light are required to reduce Q_B to Q_BH₂?

one

two

three

four

two

How does Q_BH₂ get transported to the Cyt b/c₁ complex?

Q_BH₂ attaches to a carrier and diffuses to Cyt b/c₁.

Q_BH₂ attaches directly to an arm of Cyt b/c₁ and is brought into the system.

Q_BH₂ diffuses through the membrane.

Q_BH₂ diffuses through the membrane.

What is the function of Cyt c₂?

to carry Q_B back to the reaction center

to provide energy for photosynthesis

to generate ATP

to return electrons to the reaction center

to return electrons to the reaction center

How many protons are driven from the cytoplasm to the outside of the cell per photon absorbed?

one

two

three

four

two

The Calvin-Benson cycle, the dark reaction associated with photosynthesis, is the primary CO₂ fixation pathway in nature. This cycle also provides for the synthesis of glucose and many other carbohydrate intermediates necessary for various metabolic pathways. The net reaction of the cycle, 6 CO₂'s yielding one glucose, requires the input of how many ATPs?

Six

Twelve

Eighteen

Twenty-four

Eighteen- Twelve are required at step 2 and six at step 15.

The Calvin-Benson cycle, the dark reaction associated with photosynthesis, is the primary CO₂ fixation pathway in nature. This cycle also provides for the synthesis of glucose and many other carbohydrate intermediates necessary for various metabolic pathways.

How many oxidation-reduction steps are there in the cycle?

One

Two

Three

Four

one - Step 3 is the only oxidation-reduction step.

The Calvin-Benson cycle, the dark reaction associated with photosynthesis, is the primary CO₂ fixation pathway in nature. This cycle also provides for the synthesis of glucose and many other carbohydrate intermediates necessary for various metabolic pathways.

What is the largest number of carbons in any of the intermediates produced?

Four

Five

Six

Seven

Seven