Question 1

Which statement best describes the role of enzymes in cellular respiration?

Accepted Answer

Enzymes act as biological catalysts, lowering the activation energy and speeding up reactions without being consumed.

Question 2

According to the first law of thermodynamics, which of the following is true about energy in biological systems?

Accepted Answer

Energy is only transferred, not created or destroyed, during biological processes.

Question 3

Which equation correctly represents an exergonic reaction in terms of Gibbs free energy ($$\Delta G$$)?

Accepted Answer

$$\Delta G \u003c 0$$

Question 4

A patient is found to have a deficiency in magnesium ions ($$Mg^{2+}). $$Which aspect of enzyme function is most likely to be affected?

Accepted Answer

The function of enzymes that require $$Mg^{2+} as a $$cofactor for catalysis.

Question 5

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

Enzymes and substrates fit together like a lock and key, allowing only specific interactions.

Question 6

Which graph best represents the effect of an enzyme on the activation energy of a reaction?

Accepted Answer

A graph showing a lower activation energy with enzyme than without.

Question 7

During cellular respiration, which molecule acts as the final electron acceptor in the electron transport chain?

Accepted Answer

Oxygen ($$O_2)$$

Question 8

Which process in cellular respiration occurs in the cytosol and can proceed anaerobically?

Accepted Answer

Glycolysis

Question 9

What is the main function of ATP in cellular metabolism?

Accepted Answer

ATP acts as the energy currency, transferring energy via its terminal phosphate group.

Question 10

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate to ADP.

Question 11

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding.

Question 12

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

Accepted Answer

Glycolysis → Krebs cycle → Electron transport chain

Question 13

Which molecule is reduced during the following reaction: $$XH_2 + $$NAD^+ \rightarrow X + NADH + H^+$$?

Accepted Answer

$$NAD^+$$

Question 14

If the temperature of an enzyme-catalyzed reaction is increased above the enzyme's optimum, what is the most likely outcome?

Accepted Answer

The enzyme may denature and lose its catalytic activity.

Question 15

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

Accepted Answer

The end product of a pathway inhibits an enzyme that catalyzes an early step in the pathway.

Question 16

Which of the following is true about the second law of thermodynamics in biological systems?

Accepted Answer

Energy transformations increase the disorder (entropy) of the universe.

Question 17

During oxidative phosphorylation, ATP is synthesized as protons diffuse down their gradient through which enzyme?

Accepted Answer

ATP synthase

Question 18

Which of the following is NOT a function of a coenzyme?

Accepted Answer

Serving as a permanent part of the enzyme's polypeptide chain.

Question 19

Which process directly links catabolic and anabolic reactions in the cell?

Accepted Answer

ATP synthesis and hydrolysis

Question 20

A mutation causes an enzyme's active site to change shape. What is the most likely effect on the enzyme's function?

Accepted Answer

The enzyme may lose its specificity and catalytic activity.

Cellular Respiration and Enzyme Function: Study Notes for General Biology

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