Question 1

Which of the following organisms is capable of oxygenic photosynthesis, producing O$$_2 as a $$byproduct?

Accepted Answer

Cyanobacteria

Question 2

What is the correct balanced chemical equation for photosynthesis in plants?

Accepted Answer

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

Question 3

During the light reactions of photosynthesis, what is the primary function of the photosystems?

Accepted Answer

To absorb light energy and transfer excited electrons to the electron transport chain

Question 4

Which of the following best describes the role of water in the light-dependent reactions of photosynthesis?

Accepted Answer

Water donates electrons to photosystem II, resulting in the release of O$$_2$$

Question 5

Which of the following statements about the Calvin cycle is correct?

Accepted Answer

It uses ATP and NADPH to convert CO$$_2$$ into sugars

Question 6

What is the main purpose of the electron transport chain in the thylakoid membrane during photosynthesis?

Accepted Answer

To generate a proton gradient used to produce ATP

Question 7

Which wavelength of light is most effective for driving photosynthesis, according to the absorption spectrum of chlorophyll a?

Accepted Answer

Around 680 nm (red)

Question 8

What is the fate of the excited electron from the special pair of chlorophyll a molecules in photosystem II?

Accepted Answer

It is transferred to the primary electron acceptor and then down the electron transport chain

Question 9

Which of the following best explains why plants appear green?

Accepted Answer

Chlorophyll reflects green light and absorbs red and blue wavelengths

Question 10

In the Z scheme of photosynthesis, what is the correct order of electron flow?

Accepted Answer

Photosystem II → Electron Transport Chain → Photosystem I → NADP$$^+$$

Question 11

Which process is responsible for the synthesis of ATP in both mitochondria and chloroplasts?

Accepted Answer

Chemiosmosis

Question 12

What is the main difference between cyclic and noncyclic electron flow in the light reactions of photosynthesis?

Accepted Answer

Cyclic flow involves only photosystem I and produces ATP but not NADPH or O$$_2$$

Question 13

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

Accepted Answer

It uses the proton gradient to catalyze the formation of ATP from ADP and Pi

Question 14

Which of the following is a direct product of the light-dependent reactions of photosynthesis?

Accepted Answer

ATP

Question 15

If a plant is exposed only to green light, what would you expect to happen to its rate of photosynthesis?

Accepted Answer

It would decrease because chlorophyll reflects green light

Question 16

Which of the following statements about the absorption spectrum of chlorophyll a is correct?

Accepted Answer

It absorbs light most strongly in the blue and red regions

Question 17

What is the primary role of NADP$$^+ in $$the light reactions of photosynthesis?

Accepted Answer

To act as a final electron acceptor, forming NADPH

Question 18

Which of the following best explains why the thylakoid space (lumen) becomes acidic during the light reactions?

Accepted Answer

Protons (H$$^+) $$are pumped into the thylakoid space during electron transport

Question 19

Which of the following is a real-world application of understanding the action spectrum of photosynthesis?

Accepted Answer

Designing artificial lighting for greenhouses to maximize plant growth

Question 20

A mutation prevents the formation of the cytochrome b$$_6f $$complex in a plant. Which of the following would most likely be affected?

Accepted Answer

The plant would be unable to generate a proton gradient across the thylakoid membrane

Photosynthesis: The Light Reactions and Chemiosmosis

Study Guide - Practice Questions