Q: Which of the following equations correctly summarizes cellular respiration?

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2 \rightarrow 6 \mathrm{CO}_2 + 6 \mathrm{H}_2\mathrm{O} + \text{energy}$$

Question 1

Which of the following best describes the second law of thermodynamics and its relevance to living organisms?

Accepted Answer

Every energy transfer increases the entropy (disorder) of the universe, meaning living organisms must constantly obtain energy to maintain order.

Question 2

A scientist measures the energy content of reactants and products in a chemical reaction and finds that the products have less free energy than the reactants. Which type of reaction is this, and what does it imply about energy flow?

Accepted Answer

Exergonic; energy is released to the surroundings.

Question 3

Which of the following equations correctly summarizes cellular respiration?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6 \mathrm{O}_2 ightarrow 6 \mathrm{CO}_2 + 6 \mathrm{H}_2\mathrm{O} + 	ext{energy}$$

Question 4

Which of the following best explains how ATP couples exergonic and endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases energy that can drive endergonic reactions by transferring a phosphate group to another molecule.

Question 5

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes lower the activation energy ($$E_a) $$required for a reaction to proceed.

Question 6

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Binding to the active site and blocking substrate binding.

Question 7

Which of the following best describes the role of electron carriers such as NAD$$^+$$ and FAD in cellular respiration?

Accepted Answer

They transfer electrons from food molecules to the electron transport chain, becoming reduced in the process.

Question 8

During which stage of cellular respiration is the majority of ATP produced, and what process is responsible for this ATP synthesis?

Accepted Answer

Electron transport chain; oxidative phosphorylation

Question 9

Which of the following best explains why the actual ATP yield per glucose molecule in cellular respiration is often less than the theoretical maximum?

Accepted Answer

Some protons leak across the mitochondrial membrane, and energy is used for transporting intermediates.

Question 10

Which of the following is a correct comparison between fermentation and aerobic cellular respiration?

Accepted Answer

Fermentation occurs in the absence of oxygen and yields less ATP per glucose than aerobic respiration.

Question 11

Which of the following best describes chemiosmosis in the context of oxidative phosphorylation?

Accepted Answer

The movement of protons down their concentration gradient through ATP synthase, driving the synthesis of ATP.

Question 12

Which of the following is an example of an endergonic reaction in a cell?

Accepted Answer

The synthesis of glucose during photosynthesis.

Question 13

Which of the following statements about ATP and ADP is correct?

Accepted Answer

ATP contains three phosphate groups and stores more energy than ADP.

Question 14

Which of the following best describes feedback inhibition in metabolic pathways?

Accepted Answer

The final product of a pathway inhibits an enzyme involved earlier in the pathway.

Question 15

Which of the following is a correct sequence of events in aerobic cellular respiration?

Accepted Answer

Glycolysis → Pyruvate oxidation → Citric acid cycle → Electron transport chain

Question 16

Which of the following best describes the role of oxygen in cellular respiration?

Accepted Answer

It acts as the final electron acceptor in the electron transport chain, forming water.

Question 17

A patient is diagnosed with a mitochondrial disorder that impairs the function of ATP synthase. Which process would be most directly affected?

Accepted Answer

Oxidative phosphorylation

Question 18

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

Accepted Answer

NAD$$^+ + 2e$^- + 2H$^+$$ $$\rightarrow$$ NADH + H$$^+$$

Question 19

Which of the following best explains why fats yield more ATP per gram than carbohydrates during cellular respiration?

Accepted Answer

Fats have more hydrogen atoms, providing more electrons for the electron transport chain.

Energy Acquisition and Utilization in Living Organisms: Thermodynamics, Enzymes, and Cellular Respiration

Study Guide - Practice Questions

Study Guide - Flashcards