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

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

Question 1

Which of the following best describes how cells prevent their metabolic reactions from reaching equilibrium, and why is this important for cellular function?

Accepted Answer

Cells constantly remove products of reactions, keeping the reactions moving forward and allowing continuous work.

Question 2

A scientist observes that the concentrations of reactants and products in a reaction mixture remain constant over time, and the free energy change ($$\Delta G) is $$zero. What can be concluded about the reaction?

Accepted Answer

The reaction has reached equilibrium.

Question 3

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

Accepted Answer

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

Question 4

During the oxidation of glucose in cellular respiration, which molecule acts as the primary electron carrier, and what is its role?

Accepted Answer

NAD+; it accepts electrons and becomes reduced to NADH, which then donates electrons to the electron transport chain.

Question 5

Which of the following best describes the difference between substrate-level phosphorylation and oxidative phosphorylation in ATP generation?

Accepted Answer

Substrate-level phosphorylation directly transfers a phosphate group to ADP from a substrate, while oxidative phosphorylation uses a proton gradient and ATP synthase.

Question 6

If a poison blocks the function of ATP synthase in mitochondria, which stage of cellular respiration is directly affected, and what is the immediate consequence?

Accepted Answer

Oxidative phosphorylation; ATP production via chemiosmosis is halted.

Question 7

Which of the following statements about the citric acid cycle is correct?

Accepted Answer

It occurs in the mitochondrial matrix and produces NADH, FADH2, and CO2 as major products.

Question 8

A patient has a genetic defect that prevents the regeneration of NAD+ from NADH. Which process would be most directly impaired?

Accepted Answer

Glycolysis, because NAD+ is required to accept electrons during the oxidation of glucose.

Question 9

Which of the following best explains why fermentation is necessary in the absence of oxygen?

Accepted Answer

Fermentation regenerates NAD+ from NADH, allowing glycolysis to continue producing ATP.

Question 10

Which of the following is a correct sequence of events for the flow of electrons during aerobic cellular respiration?

Accepted Answer

Glucose $$\rightarrow$$ NADH $$\rightarrow$$ Electron Transport Chain $$\rightarrow$$ Oxygen

Question 11

If the concentration of products in a reversible reaction increases, what will happen to the direction and rate of the reaction according to the principles of chemical equilibrium?

Accepted Answer

The reaction will shift toward the reactants, and the rate of the reverse reaction will increase.

Question 12

Which anatomical feature of the mitochondrion is most directly responsible for establishing the proton gradient used in ATP synthesis?

Accepted Answer

The inner mitochondrial membrane, which houses the electron transport chain and ATP synthase.

Question 13

A mutation causes a defect in one of the enzymes of the citric acid cycle. What is the most likely effect on cellular respiration?

Accepted Answer

There will be a decrease in NADH and FADH2 production, leading to reduced ATP generation in oxidative phosphorylation.

Question 14

Which of the following best describes the free energy change ($$\Delta G) $$during the process of cellular respiration?

Accepted Answer

$$\Delta G is $$negative, indicating that energy is released as glucose is oxidized.

Question 15

Which of the following is an example of a redox reaction in cellular respiration?

Accepted Answer

NAD+ is reduced to NADH as it accepts electrons from glucose derivatives.

Question 16

If the electron transport chain is inhibited, what immediate effect does this have on the NAD+/NADH ratio in the mitochondria?

Accepted Answer

NADH accumulates and NAD+ becomes depleted, halting upstream processes like the citric acid cycle and glycolysis.

Question 17

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

Accepted Answer

Oxygen serves as the final electron acceptor in the electron transport chain, allowing for the regeneration of NAD+ and FAD.

Question 18

Which of the following would most likely occur if a cell's supply of oxygen is suddenly cut off?

Accepted Answer

The cell will switch to fermentation to regenerate NAD+ and continue glycolysis, but ATP production will decrease.

Question 19

Which of the following is a characteristic of a chemical reaction at equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.

Cellular Respiration: Free Energy, Pathways, and ATP Production

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