$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$$

Question 1

Which of the following best represents the overall equation for cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 ightarrow 6CO_2 + 6H_2O + 	ext{energy}$$

Question 2

Which structure within the mitochondrion is primarily responsible for housing the electron transport chain (ETC)?

Accepted Answer

Cristae (folds of the inner membrane)

Question 3

During glycolysis, what is the net gain of ATP and NADH molecules per molecule of glucose?

Accepted Answer

2 ATP and 2 NADH

Question 4

Why is glycolysis considered an ancient metabolic pathway?

Accepted Answer

It occurs in the cytosol and does not require oxygen, allowing early prokaryotes to generate energy before oxygen was present in the atmosphere.

Question 5

What is the primary purpose of NADH and FADH$$_2 in $$cellular respiration?

Accepted Answer

To carry electrons to the electron transport chain for ATP production

Question 6

Which process occurs when oxygen is NOT present after glycolysis in animal cells, and what is its main purpose?

Accepted Answer

Lactic acid fermentation; to regenerate NAD$$^+$$ for glycolysis

Question 7

Which of the following is a correct description of the fate of pyruvate in the presence of oxygen?

Accepted Answer

It enters the mitochondria and is converted to acetyl-CoA.

Question 8

During the Krebs cycle, what is the main function of acetyl-CoA?

Accepted Answer

To combine with oxaloacetate to form citric acid, starting the cycle

Question 9

What is the role of oxygen in the electron transport chain?

Accepted Answer

It is the final electron acceptor, forming water.

Question 10

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

Accepted Answer

Protons would accumulate in the intermembrane space, but ATP production would decrease sharply.

Question 11

Which of the following best explains why lactic acid fermentation is reversible in humans, but alcoholic fermentation is not?

Accepted Answer

Lactic acid can be converted back to pyruvate when oxygen is available, but ethanol cannot.

Question 12

Which of the following is NOT a product of the Krebs cycle per glucose molecule?

Accepted Answer

6 O$$_2$$

Question 13

A patient is exposed to cyanide, which inhibits the final protein in the electron transport chain. What is the most direct consequence?

Accepted Answer

NADH and FADH$$_2$$ will accumulate because electrons cannot be transferred to oxygen.

Question 14

Which of the following best describes the evolutionary significance of glycolysis?

Accepted Answer

It is found in nearly all organisms, suggesting it evolved early in the history of life.

Question 15

Which of the following statements about the mitochondria is FALSE?

Accepted Answer

The outer membrane contains the electron transport chain.

Question 16

Which step in cellular respiration produces the most ATP?

Accepted Answer

Electron transport chain and oxidative phosphorylation

Question 17

In the absence of oxygen, why does glycolysis continue but the Krebs cycle and ETC do not?

Accepted Answer

Glycolysis occurs in the cytosol and does not require oxygen, while the Krebs cycle and ETC require oxygen and mitochondria.

Question 18

Which of the following is a direct result of the proton gradient established by the electron transport chain?

Accepted Answer

ATP is synthesized as protons flow through ATP synthase.

Question 19

Which of the following best explains why we breathe oxygen?

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain, allowing ATP production.

Question 20

A yeast cell is placed in an anaerobic environment. Which products will accumulate as a result of alcoholic fermentation?

Accepted Answer

Ethanol, CO$$_2$$, and ATP

Cellular Respiration: Structure, Function, and Metabolic Pathways

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