Question 1

Which of the following statements best describes a catabolic pathway in cellular metabolism?

Accepted Answer

It releases energy by breaking down complex molecules into simpler compounds.

Question 2

Which type of energy is stored due to an object's position or structure, such as a stretched spring or a molecule's chemical bonds?

Accepted Answer

Potential energy

Question 3

According to the first law of thermodynamics, which of the following is true for biological systems?

Accepted Answer

Energy is conserved; organisms absorb energy and release metabolic wastes to their surroundings.

Question 4

A reaction has $$\Delta G = -15\ \mathrm{kJ/mol} at $$physiological conditions. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and spontaneous.

Question 5

Which equation correctly relates free energy change to enthalpy, entropy, and temperature?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 6

Which of the following best explains why living cells must remain open systems?

Accepted Answer

Open systems enable continuous work by preventing equilibrium and allowing constant exchange of energy and materials.

Question 7

ATP hydrolysis is considered exergonic because:

Accepted Answer

It releases energy that can be used to power endergonic cellular processes.

Question 8

Which of the following is NOT a type of cellular work powered by ATP?

Accepted Answer

Thermal work, such as increasing body temperature

Question 9

Enzymes speed up metabolic reactions by:

Accepted Answer

Lowering the activation energy ($$E_a) $$required for the reaction to occur

Question 10

Which factor does NOT directly affect enzyme activity?

Accepted Answer

Substrate concentration always increases enzyme activity indefinitely

Question 11

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and blocking substrate binding

Question 12

Which scenario best illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway binds to an earlier enzyme, reducing its activity.

Question 13

If a cell's ATP levels drop significantly, which process would be most directly affected?

Accepted Answer

Active transport of ions against their concentration gradient

Question 14

Which of the following statements about enzyme-catalyzed reactions is correct?

Accepted Answer

Enzymes lower the activation energy but do not change the overall free energy ($$\Delta G) of $$the reaction.

Question 15

Which type of enzyme inhibitor binds to a site other than the active site and changes the enzyme's shape, reducing its activity?

Accepted Answer

Noncompetitive inhibitor

Question 16

A scientist measures the entropy ($$S) of a $$system before and after a spontaneous reaction. What should they expect?

Accepted Answer

Entropy increases as the system becomes more disordered.

Question 17

Which of the following best describes the role of ATP in coupling exergonic and endergonic reactions?

Accepted Answer

ATP hydrolysis provides energy to drive endergonic reactions by transferring a phosphate group.

Question 18

Which of the following is an example of chemical energy in biological systems?

Accepted Answer

The energy stored in glucose molecules

Question 19

A cell is exposed to a toxin that irreversibly binds to its enzymes. What type of inhibition is this?

Accepted Answer

Irreversible inhibition

Question 20

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction in a human cell?

Accepted Answer

Adding more substrate when the enzyme is not saturated

Metabolism, Energy, and Enzyme Function in Biological Systems

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