$$6 \mathrm{CO}_2 + 6 \mathrm{H}_2O + \text{light energy} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2$$

Question 1

Which of the following best describes the overall chemical equation for photosynthesis?

Accepted Answer

$$6 \mathrm{CO}_2 + 6 \mathrm{H}_2O + 	ext{light energy} ightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2$$

Question 2

Where do the light-dependent reactions of photosynthesis take place within the chloroplast?

Accepted Answer

In the thylakoid membrane

Question 3

What is the primary function of the Calvin cycle in photosynthesis?

Accepted Answer

To use ATP and NADPH to convert $$\mathrm{CO}_2$$ into G3P

Question 4

Which enzyme catalyzes the fixation of $$\mathrm{CO}_2 to $$ribulose bisphosphate (RuBP) in the Calvin cycle?

Accepted Answer

Rubisco

Question 5

During the light-dependent reactions, what is the source of electrons for the electron transport chain?

Accepted Answer

Water ($$\mathrm{H}_2O)$$

Question 6

Which molecule is the direct product of the Calvin cycle and can be used to synthesize glucose?

Accepted Answer

Glyceraldehyde-3-phosphate (G3P)

Question 7

How many molecules of ATP and NADPH are required to produce one net G3P molecule in the Calvin cycle?

Accepted Answer

$$9$$ ATP and $$6$$ NADPH

Question 8

What is the main reason that the Calvin cycle requires more ATP than NADPH?

Accepted Answer

Additional ATP is required for RuBP regeneration

Question 9

Which of the following best describes the difference between ATP production in mitochondria and chloroplasts?

Accepted Answer

Mitochondria use oxidative phosphorylation, while chloroplasts use photophosphorylation

Question 10

In C4 plants, what is the role of PEP carboxylase?

Accepted Answer

It fixes $$\mathrm{CO}_2$$ into a four-carbon compound in mesophyll cells

Question 11

Which of the following statements correctly distinguishes C4 plants from C3 plants?

Accepted Answer

C4 plants separate $$\mathrm{CO}_2$$ fixation and the Calvin cycle spatially

Question 12

What is the main adaptive advantage of CAM plants in arid environments?

Accepted Answer

They temporally separate $$\mathrm{CO}_2$$ fixation and the Calvin cycle to minimize water loss

Question 13

Which of the following best explains why oxygen is produced during the light-dependent reactions?

Accepted Answer

Water is split to provide electrons, releasing oxygen as a byproduct

Question 14

If a plant's thylakoid membranes were damaged, which process would be directly affected?

Accepted Answer

The light-dependent reactions

Question 15

Which of the following is a fate of G3P produced by the Calvin cycle?

Accepted Answer

It can be converted to glucose, stored as starch, or used in glycolysis

Question 16

Which of the following best describes chemiosmosis in chloroplasts?

Accepted Answer

Protons are pumped into the thylakoid space, creating a gradient that drives ATP synthesis

Question 17

A plant is exposed to a toxin that inhibits Rubisco. What is the most immediate effect on photosynthesis?

Accepted Answer

Carbon fixation in the Calvin cycle would stop

Question 18

Which of the following is true about the regeneration phase of the Calvin cycle?

Accepted Answer

It uses ATP to regenerate RuBP from G3P

Question 19

In which cellular compartment does the Calvin cycle occur?

Accepted Answer

Stroma of the chloroplast

Question 20

Which of the following is a key difference between C3 and CAM plants?

Accepted Answer

CAM plants separate $$\mathrm{CO}_2$$ fixation and the Calvin cycle temporally, while C3 plants do not

Photosynthesis: Mechanisms, Pathways, and Comparative Bioenergetics

Study Guide - Practice Questions