Q: The summary equation for cellular respiration is:

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

Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways break down complex molecules into simpler ones, releasing energy, while anabolic pathways build complex molecules from simpler ones, requiring energy input.

Question 2

A reaction has a $$\Delta G of$$ $$-7.3$$ kcal/mol. Which of the following statements is TRUE about this reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 3

Which of the following best explains why ATP is often called the 'energy currency' of the cell?

Accepted Answer

ATP hydrolysis releases energy that can be coupled to endergonic reactions, allowing the cell to perform work.

Question 4

Which of the following statements about enzymes is CORRECT?

Accepted Answer

Enzymes lower the activation energy barrier, increasing the rate of spontaneous reactions.

Question 5

A scientist adds a molecule to an enzyme-catalyzed reaction. The molecule binds to a site other than the active site and decreases enzyme activity. What is this type of regulation called?

Accepted Answer

Allosteric inhibition

Question 6

Which of the following best describes the role of NAD$$^+ in $$cellular respiration?

Accepted Answer

NAD$$^+$$ acts as an electron carrier, accepting electrons during redox reactions and becoming reduced to NADH.

Question 7

The summary equation for cellular respiration is:

Accepted Answer

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

Question 8

During glycolysis, why is ATP required in the initial steps?

Accepted Answer

ATP is required to phosphorylate glucose, making it more chemically reactive and trapping it in the cell.

Question 9

Which of the following correctly matches the stage of cellular respiration with its location in eukaryotic cells?

Accepted Answer

Oxidative phosphorylation – inner mitochondrial membrane

Question 10

Which process produces the most ATP per molecule of glucose oxidized in cellular respiration?

Accepted Answer

Oxidative phosphorylation (electron transport chain and chemiosmosis)

Question 11

A patient is diagnosed with a genetic disorder that impairs the function of the electron transport chain. Which of the following would most likely be observed in this patient’s cells?

Accepted Answer

Decreased proton gradient across the inner mitochondrial membrane

Question 12

Which of the following statements about substrate-level phosphorylation and oxidative phosphorylation is TRUE?

Accepted Answer

Substrate-level phosphorylation generates ATP during glycolysis and the citric acid cycle, while oxidative phosphorylation generates ATP using a proton gradient across the inner mitochondrial membrane.

Question 13

Which of the following best explains why the citric acid cycle is considered a cycle?

Accepted Answer

It regenerates oxaloacetate, the molecule that reacts with acetyl-CoA to begin the cycle again.

Question 14

Which of the following is a direct result of the exergonic 'slide' of electrons down the electron transport chain?

Accepted Answer

Pumping of protons (H$$^+) $$across the inner mitochondrial membrane, creating a proton gradient

Question 15

Which of the following food molecules can be used by cells to generate ATP, in addition to glucose?

Accepted Answer

Proteins, fatty acids, and other carbohydrates

Question 16

A cell is exposed to a toxin that inhibits allosteric regulators of enzymes. Which of the following is the most likely consequence?

Accepted Answer

The cell will lose the ability to fine-tune enzyme activity in response to changing conditions.

Question 17

Which of the following best describes a spontaneous process in the context of thermodynamics?

Accepted Answer

A process that can occur without energy input and results in a decrease in free energy ($$\Delta G \u003c 0).$$

Question 18

Which of the following is an example of kinetic energy in a biological system?

Accepted Answer

A proton moving down its concentration gradient through ATP synthase

Question 19

A mutation causes an enzyme’s active site to change shape. Which of the following is the most likely result?

Accepted Answer

The enzyme will lose specificity and may not bind its intended substrate.

Question 20

During intense exercise, muscle cells switch to lactic acid fermentation. Which of the following best explains why this occurs?

Accepted Answer

NAD$$^+$$ must be regenerated from NADH to allow glycolysis to continue in the absence of sufficient oxygen.

Metabolism and Energy: Thermodynamics, ATP, Enzymes, and Cellular Respiration

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