Q: During non-cyclic photophosphorylation, what is the correct sequence of electron flow?

$$\text{PSII} \rightarrow \text{PSI} \rightarrow \text{NADP}^+$$

Q: Which of the following is the correct summary equation for the Calvin cycle per one glucose molecule produced?

$$6 \ \text{CO}_2 + 18 \ \text{ATP} + 12 \ \text{NADPH} \rightarrow 1 \ \text{glucose} + 18 \ \text{ADP} + 12 \ \text{NADP}^+ + 18 \ \text{P}_i$$

Question 1

Which of the following best describes the main purpose of the light-dependent reactions in photosynthesis?

Accepted Answer

To capture light energy and convert it into chemical energy in the form of ATP and NADPH.

Question 2

During non-cyclic photophosphorylation, what is the correct sequence of electron flow?

Accepted Answer

$$	ext{PSII} ightarrow 	ext{PSI} ightarrow 	ext{NADP}^+$$

Question 3

Which enzyme is responsible for catalyzing the fixation of carbon dioxide in the Calvin cycle?

Accepted Answer

RuBisCO

Question 4

What is the main function of cyclic photophosphorylation in photosynthesis?

Accepted Answer

To generate extra ATP when the Calvin cycle requires more ATP than NADPH.

Question 5

Which of the following is a product of the light-dependent reactions but NOT of cyclic photophosphorylation?

Accepted Answer

NADPH

Question 6

In the Calvin cycle, how many molecules of ATP and NADPH are required to produce one molecule of glucose?

Accepted Answer

$$18$$ ATP and $$12$$ NADPH

Question 7

Which of the following statements about Photosystem II (PSII) is correct?

Accepted Answer

PSII splits water molecules, releasing O$$_2$$ and providing electrons to the electron transport chain.

Question 8

A plant cell is exposed to light, but the Calvin cycle is inhibited. Which of the following would you expect to accumulate?

Accepted Answer

ATP and NADPH

Question 9

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

Accepted Answer

It does not involve the splitting of water by PSII.

Question 10

What is the role of the proton gradient across the thylakoid membrane during the light-dependent reactions?

Accepted Answer

It drives the synthesis of ATP via ATP synthase.

Question 11

Which of the following is the correct summary equation for the Calvin cycle per one glucose molecule produced?

Accepted Answer

$$6 \ 	ext{CO}_2 + 18 \ 	ext{ATP} + 12 \ 	ext{NADPH} ightarrow 1 \ 	ext{glucose} + 18 \ 	ext{ADP} + 12 \ 	ext{NADP}^+ + 18 \ 	ext{P}_i$$

Question 12

A mutation disables the function of ferredoxin-NADP$$^+$$ reductase (FNR) in a plant. Which process would be directly affected?

Accepted Answer

Reduction of NADP$$^+ to $$NADPH

Question 13

Which of the following best describes the fate of electrons excited in Photosystem I (PSI) during non-cyclic photophosphorylation?

Accepted Answer

They are transferred to NADP$$^+ to $$form NADPH.

Question 14

Which of the following is NOT a direct product of the light-dependent reactions?

Accepted Answer

Glucose

Question 15

If a plant is exposed to a chemical that blocks the electron transport chain between PSII and PSI, which of the following would most likely occur?

Accepted Answer

ATP and NADPH production would both decrease.

Question 16

Which of the following best explains why the Calvin cycle is considered 'light-independent'?

Accepted Answer

It can occur in the dark as long as ATP and NADPH are available.

Question 17

Which of the following is the main reason why Photosystem II (PSII) is not involved in cyclic photophosphorylation?

Accepted Answer

PSII's main function is to split water and provide electrons, which is not needed in cyclic electron flow.

Question 18

A scientist measures the oxygen output of a plant under two conditions: (1) normal light, and (2) when only cyclic photophosphorylation is occurring. What result should the scientist expect?

Accepted Answer

Oxygen output is lower during cyclic photophosphorylation.

Question 19

Which of the following best describes the role of RuBP in the Calvin cycle?

Accepted Answer

It is the 5-carbon molecule that combines with CO$$_2 to $$initiate carbon fixation.

Photosynthesis: Light-Dependent and Light-Independent Reactions

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