$$ \mathrm{C_6H_{12}O_6} + 6\ \mathrm{O_2} \rightarrow 6\ \mathrm{CO_2} + 6\ \mathrm{H_2O} + \text{energy (ATP)} $$

Question 1

Which of the following best explains why the electron transport chain (ETC) in cellular respiration is considered spontaneous?

Accepted Answer

Because electrons move from species with lower to higher redox potential, releasing free energy at each step.

Question 2

During photosynthesis, what is the primary role of light energy in the electron transport chain?

Accepted Answer

To excite electrons in photosystems, enabling the transfer of electrons through the chain.

Question 3

Which of the following is the main end product of the light-dependent reactions of photosynthesis?

Accepted Answer

ATP and NADPH

Question 4

How is the energy released from electron transfer in the mitochondrial electron transport chain primarily used?

Accepted Answer

To create a proton gradient across the inner mitochondrial membrane

Question 5

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

Accepted Answer

It uses ATP and NADPH produced in the light-dependent reactions to fix atmospheric CO$$_2.$$

Question 6

A mutation prevents the formation of a proton gradient in the mitochondria. Which process would be most directly affected?

Accepted Answer

ATP synthesis by ATP synthase

Question 7

Which of the following best describes the difference in how electron transport chains operate in photosynthesis versus cellular respiration?

Accepted Answer

Photosynthesis requires energy input from light to drive electron flow, while cellular respiration's electron flow is energetically downhill.

Question 8

Which of the following equations correctly represents the overall process of cellular respiration?

Accepted Answer

$$ \mathrm{C_6H_{12}O_6} + 6\ \mathrm{O_2} ightarrow 6\ \mathrm{CO_2} + 6\ \mathrm{H_2O} + 	ext{energy (ATP)} $$

Question 9

In a scenario where a plant is exposed to light but deprived of CO$$_2$$, which of the following would most likely occur?

Accepted Answer

The light-dependent reactions would proceed, but the Calvin Cycle would halt.

Question 10

Which of the following is a correct statement about the role of NADPH in photosynthesis?

Accepted Answer

NADPH provides reducing power for the Calvin Cycle to fix carbon.

Question 11

A patient is diagnosed with a mitochondrial disorder that impairs the electron transport chain. Which symptom is most likely to be observed?

Accepted Answer

Reduced ATP production leading to muscle weakness

Question 12

Which of the following best explains why oxygen is required for cellular respiration?

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain, allowing for continued electron flow and ATP production.

Question 13

If a toxin blocks ATP synthase in the chloroplast, which of the following would be the most immediate effect?

Accepted Answer

ATP production in the light-dependent reactions would decrease.

Question 14

Which of the following is a key difference between the electron transport chains of mitochondria and chloroplasts?

Accepted Answer

Mitochondrial ETC uses oxygen as the final electron acceptor, while chloroplast ETC uses NADP$$^+.$$

Question 15

A scientist measures the redox potential at various points along the mitochondrial electron transport chain. What trend should they observe?

Accepted Answer

Redox potential increases from the first to the last electron carrier.

Photosynthesis vs. Cellular Respiration & Electron Transport Chains

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