Question 1

Which of the following best describes the main function of the thylakoid membrane in chloroplasts during photosynthesis?

Accepted Answer

It is the site where electron transport chains and ATP synthases are embedded, facilitating light-dependent reactions.

Question 2

Which equation correctly represents the overall light-dependent reaction of photosynthesis?

Accepted Answer

$$2H_2O + 2NADP^+ + 3ADP + 3P_i \rightarrow O_2$ + 2NADPH + 3ATP$$

Question 3

What is the primary role of the light-harvesting complex in the thylakoid membrane?

Accepted Answer

To absorb and transfer energy from sunlight to reaction centers.

Question 4

Which of the following statements about the electron transport chain in photosynthesis is correct?

Accepted Answer

Electrons move through protein complexes, creating a proton gradient used to synthesize ATP.

Question 5

In the process of non-cyclic photophosphorylation, what is the final electron acceptor?

Accepted Answer

NADP$$^+$$

Question 6

Which of the following best explains why water is split during the light-dependent reactions of photosynthesis?

Accepted Answer

To provide electrons to replace those lost by chlorophyll in the reaction center.

Question 7

A mutation prevents the formation of the proton gradient across the thylakoid membrane. Which process would be most directly affected?

Accepted Answer

The production of ATP by ATP synthase.

Question 8

Which of the following is a direct product of the light-dependent reactions that is used in the Calvin cycle?

Accepted Answer

NADPH

Question 9

If a plant is exposed to a chemical that blocks the transfer of electrons from photosystem II to photosystem I, what would be the most immediate consequence?

Accepted Answer

NADPH production would decrease.

Question 10

Which of the following best describes the role of ATP synthase in the thylakoid membrane?

Accepted Answer

It uses the energy from the proton gradient to convert ADP and $$P_i$$ into ATP.

Question 11

Which of the following is NOT a component of the photosystem complex?

Accepted Answer

Cytochrome c oxidase

Question 12

During the light-dependent reactions, which molecule is oxidized and which is reduced?

Accepted Answer

Water is oxidized and NADP$$^+ is $$reduced.

Question 13

Which process is responsible for the release of oxygen during photosynthesis?

Accepted Answer

The splitting of water molecules in the thylakoid membrane.

Question 14

A scientist measures the pH inside the thylakoid lumen and finds it to be much lower than in the stroma. What does this indicate about the activity of the electron transport chain?

Accepted Answer

Protons are being actively transported into the lumen, creating a proton gradient.

Question 15

Which of the following best explains why cyclic photophosphorylation does not produce NADPH?

Accepted Answer

Electrons return to photosystem I instead of reducing NADP$$^+.$$

Photophosphorylation and Photosynthesis: Mechanisms and Components

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