Question 1

Which of the following best describes the role of enzymes in metabolic pathways?

Accepted Answer

Enzymes act as macromolecules that catalyze specific reactions, lowering activation energy and increasing reaction rates.

Question 2

Which equation correctly represents the relationship between Gibbs free energy ($$G$$), enthalpy ($$H$$), temperature ($$T$$), and entropy ($$S$$)?

Accepted Answer

$$G = H - TS$$

Question 3

A reaction has $$\Delta G \u003c 0. $$What does this indicate about the reaction?

Accepted Answer

The reaction is spontaneous and can perform work.

Question 4

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

Accepted Answer

The random motion of particles in the cytoplasm.

Question 5

What is the primary difference between catabolism and anabolism?

Accepted Answer

Catabolism breaks down molecules to release energy, while anabolism builds complex molecules using energy.

Question 6

Which of the following statements about entropy ($$S) is $$correct?

Accepted Answer

Entropy is a measure of system disorder; higher entropy means more disorder.

Question 7

Consider a cell transporting sodium ions against their concentration gradient. Which statement best describes this process?

Accepted Answer

It is a nonspontaneous process that requires an input of energy.

Question 8

Which of the following is a correct interpretation of the First Law of Thermodynamics in biological systems?

Accepted Answer

Energy cannot be created or destroyed, only transformed from one form to another.

Question 9

A cell is at equilibrium with its surroundings. What can be said about its ability to do work?

Accepted Answer

It cannot do work because there is no free energy available.

Question 10

Which of the following scenarios best illustrates the concept of a chemical gradient doing work in a cell?

Accepted Answer

Diffusion of oxygen from high to low concentration across a membrane.

Question 11

If a reaction has $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0$$, under what condition will the reaction be spontaneous?

Accepted Answer

At high temperatures, because the $$-T\Delta S$$ term will outweigh $$\Delta H.$$

Question 12

Which of the following best explains why ATP hydrolysis is often coupled to endergonic reactions in cells?

Accepted Answer

ATP hydrolysis is exergonic and releases free energy that can drive nonspontaneous processes.

Question 13

Which formula represents the change in free energy for a reaction?

Accepted Answer

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

Question 14

Which of the following is NOT a form of energy that can be used to do work in biological systems?

Accepted Answer

Random thermal motion of particles at equilibrium.

Question 15

A metabolic pathway consists of several reactions, each catalyzed by a specific enzyme. What is the main advantage of this organization?

Accepted Answer

It enables precise control and regulation of each step in the pathway.

Question 16

Which of the following statements about equilibrium in biological systems is correct?

Accepted Answer

A system at equilibrium cannot do work because $$\Delta G = 0.$$

Question 17

Which of the following best describes an endergonic reaction?

Accepted Answer

A reaction that requires energy input and is nonspontaneous ($$\Delta G \u003e 0).$$

Question 18

Which of the following is a real-world example of a gradient doing work in a biological system?

Accepted Answer

Movement of ions through a voltage-gated channel during nerve impulse transmission.

Question 19

Which statement best explains why living organisms are able to maintain order and low entropy?

Accepted Answer

They use energy from their environment to build and maintain complex structures, increasing the entropy of their surroundings.

Metabolism, Energy, and Entropy in Biological Systems

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