$$6 \ \mathrm{CO}_2 + 6 \ \mathrm{H}_2\mathrm{O} + \text{light energy} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \ \mathrm{O}_2$$

Question 1

Which of the following best represents the overall equation for photosynthesis?

Accepted Answer

$$6 \ \mathrm{CO}_2 + 6 \ \mathrm{H}_2\mathrm{O} + 	ext{light energy} ightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \ \mathrm{O}_2$$

Question 2

Where in the chloroplast do the light reactions of photosynthesis take place?

Accepted Answer

In the thylakoid membranes

Question 3

Which of the following is a direct product of the light reactions and is used in the Calvin cycle?

Accepted Answer

NADPH

Question 4

What is the main function of the enzyme rubisco in the Calvin cycle?

Accepted Answer

It catalyzes the fixation of CO$$_2 to $$RuBP

Question 5

During the light reactions, what is the primary role of water?

Accepted Answer

To provide electrons to Photosystem II

Question 6

Which of the following best describes chemiosmosis in the context of photosynthesis?

Accepted Answer

The movement of protons through ATP synthase to generate ATP

Question 7

How many molecules of G3P exit the Calvin cycle per three molecules of CO$$_2$$ fixed, and what happens to the remaining G3P?

Accepted Answer

One G3P exits; the rest are used to regenerate RuBP

Question 8

Which of the following correctly matches the location and process in the chloroplast?

Accepted Answer

Thylakoid membrane – Light reactions

Question 9

What is the main difference between Photosystem I (PSI) and Photosystem II (PSII)?

Accepted Answer

PSII splits water and releases O$$_2$$, while PSI does not

Question 10

Which of the following best explains how ATP is generated during the light reactions?

Accepted Answer

A proton gradient drives ATP synthase to convert ADP and P$$_i$$ into ATP

Question 11

If a plant is exposed to a chemical that blocks the electron transport chain between PSII and PSI, which of the following would be directly affected?

Accepted Answer

Production of ATP and NADPH

Question 12

Which phase of the Calvin cycle uses ATP and NADPH to convert 3-phosphoglycerate into G3P?

Accepted Answer

Reduction

Question 13

A mutation in a plant prevents the regeneration of RuBP. What would be the immediate consequence for the Calvin cycle?

Accepted Answer

The cycle would stop because CO$$_2$$ could not be fixed

Question 14

Which of the following is NOT a product of the light reactions of photosynthesis?

Accepted Answer

Glucose

Question 15

In a real-world scenario, why might a plant growing in low light conditions have difficulty producing enough sugar?

Accepted Answer

Insufficient ATP and NADPH are produced in the light reactions

Question 16

Which of the following best describes the fate of oxygen produced during photosynthesis?

Accepted Answer

It is released as a byproduct into the atmosphere

Question 17

If the thylakoid membrane is damaged and becomes leaky to protons, what is the most likely effect on ATP synthesis?

Accepted Answer

ATP synthesis would decrease due to loss of the proton gradient

Question 18

Which molecule acts as the final electron acceptor in the light reactions of photosynthesis?

Accepted Answer

NADP$$^+$$

Question 19

What is the significance of G3P produced in the Calvin cycle?

Accepted Answer

It is a precursor for glucose and other organic molecules

Question 20

Which of the following best explains how the light reactions and Calvin cycle are interconnected?

Accepted Answer

The light reactions provide ATP and NADPH to the Calvin cycle

Photosynthesis: Structure, Function, and Mechanisms

Study Guide - Practice Questions