BioInteractive Photosystems I and II 3

Question 1

In cyclic electron flow, which photosystem is primarily involved?

Accepted Answer

Photosystem I

Answer

Neither photosystem

Answer

Photosystem II

Answer

Both equally

Question 2

Compared to non-cyclic electron flow, what does cyclic electron flow produce?

Accepted Answer

ATP without NADPH or O2

Answer

More NADPH but no ATP

Answer

Additional O2 only

Answer

Both ATP and NADPH

Question 3

Under what condition would a plant preferentially shift to cyclic electron flow?

Accepted Answer

When NADPH levels are high relative to ATP needs

Answer

When the plant needs to release more oxygen

Answer

When water supply is abundant

Answer

When CO2 concentration is very high

Question 4

What is the ratio of ATP to NADPH consumed per three CO2 molecules fixed in the Calvin cycle?

Accepted Answer

3 ATP : 2 NADPH

Answer

1 ATP : 1 NADPH

Answer

2 ATP : 1 NADPH

Answer

1 ATP : 2 NADPH

Question 5

What does the Z-scheme diagram in photosynthesis illustrate?

Accepted Answer

The changes in redox potential of electrons as they travel from water through PSII and PSI to NADPH

Answer

How CO2 is incorporated into organic molecules

Answer

How ATP synthase generates ATP

Answer

The spatial arrangement of chloroplast membranes

Question 6

How do the products of the photosystems connect to the Calvin cycle?

Accepted Answer

Photosystems produce ATP and NADPH that supply the energy and reducing power for CO2 fixation in the Calvin cycle

Answer

The Calvin cycle occurs inside the thylakoid membrane alongside the photosystems

Answer

The Calvin cycle provides electrons back to Photosystem II

Answer

The two processes are entirely independent and do not exchange products

Question 7

The herbicide DCMU (diuron) blocks photosynthesis by inhibiting electron transfer at which site?

Accepted Answer

The plastoquinone binding site in PSII

Answer

The NADP+ reductase enzyme in PSI

Answer

The plastocyanin binding site in PSI

Answer

The ATP synthase proton channel