Question 1

Which of the following organisms is capable of oxygenic photosynthesis, producing O2 as a byproduct?

Accepted Answer

Cyanobacteria

Question 2

What is the overall chemical equation for photosynthesis in plants, and what does the sign of $$\Delta G$$ indicate about the reaction?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$; $$\Delta G is $$positive, indicating the reaction requires energy.

Question 3

Which pigment is primarily responsible for light absorption in oxygenic photosynthesis?

Accepted Answer

Chlorophyll a

Question 4

In the Calvin cycle, how many ATP and NADPH molecules are required to synthesize one molecule of hexose (glucose)?

Accepted Answer

18 ATP and 12 NADPH

Question 5

Which of the following best describes the difference between oxygenic and anoxygenic phototrophy?

Accepted Answer

Oxygenic phototrophy produces O2, while anoxygenic does not.

Question 6

Which of the following is a major reason why green sulfur bacteria cannot use H2O as an electron donor?

Accepted Answer

Their photosystem does not have enough redox potential to oxidize H2O.

Question 7

What is the primary function of the proton motive force (PMF) generated during phototrophy?

Accepted Answer

To drive ATP synthesis via photophosphorylation

Question 8

Which of the following statements about bacteriorhodopsin-based phototrophy is correct?

Accepted Answer

It uses light to pump protons and generate ATP, but does not involve electron transport chains.

Question 9

A purple non-sulfur bacterium needs NADPH for biosynthesis. Which strategy does it use to generate NADPH?

Accepted Answer

Reverse electron flow using energy from PMF

Question 10

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

Accepted Answer

CO2

Question 11

Why is oxygenic photosynthesis considered endergonic?

Accepted Answer

It requires an input of energy from light to drive the synthesis of glucose.

Question 12

Which of the following organisms is a strict anaerobe and performs anoxygenic phototrophy?

Accepted Answer

Green sulfur bacteria

Question 13

What is the role of light-harvesting complexes in photosystems?

Accepted Answer

They absorb light and transfer energy to the reaction center.

Question 14

Which molecule acts as the primary electron donor in oxygenic photosynthesis?

Accepted Answer

H2O

Question 15

In the Calvin cycle, what is the enzyme responsible for carbon fixation?

Accepted Answer

Rubisco

Question 16

Which of the following best explains why bacteriorhodopsin-based phototrophy cannot support long-term anaerobic growth?

Accepted Answer

O2 is required for the synthesis of retinal, the chromophore.

Question 17

Which of the following is a real-world application of understanding phototrophic diversity in prokaryotes?

Accepted Answer

Developing bioengineered bacteria for bioremediation using anoxygenic phototrophy

Question 18

Which of the following statements about the energy yield from oxygenic photolysis is correct?

Accepted Answer

One round produces O2, 3 ATP, and 2 NADPH.

Question 19

Which of the following is a plausible consequence if a photosynthetic organism lacked light-harvesting complexes?

Accepted Answer

It would be unable to absorb light efficiently, reducing photosynthetic output.

Prokaryotic Phototrophy and Photosynthesis: Mechanisms and Diversity

Study Guide - Practice Questions