Q: A reaction has $$\Delta H = -10 kJ$$, $$\Delta S = 0.02 kJ/K$$, and occurs at $$T = 300 K. $$What is $$\Delta G$$ for this reaction?

$$\Delta G = -10 - (300 \times 0.02) = -10 - 6 = -16 kJ$$

Question 1

Which of the following best describes a metabolic pathway?

Accepted Answer

A series of interconnected chemical reactions that convert a starting molecule to an end product through multiple enzyme-catalyzed steps.

Question 2

What are two main benefits of organizing cellular reactions into metabolic pathways?

Accepted Answer

Maximizing energy harvested and minimizing energy lost as heat.

Question 3

Which equation correctly represents the change in free energy for a reaction?

Accepted Answer

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

Question 4

A reaction has $$\Delta H = -10 kJ$$, $$\Delta S = 0.02 kJ/K$$, and occurs at $$T = 300 K. $$What is $$\Delta G$$ for this reaction?

Accepted Answer

$$\Delta G = -10 - (300 	imes 0.02) = -10 - 6 = -16 kJ$$

Question 5

Which statement best distinguishes catabolic and anabolic pathways?

Accepted Answer

Catabolic pathways break down large molecules into smaller ones, releasing energy; anabolic pathways build larger molecules from smaller ones, requiring energy.

Question 6

Which of the following is true about exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions release energy and are spontaneous; endergonic reactions require energy and are nonspontaneous.

Question 7

If the free energy change for reaction A→B is $$-20 kJ $$and for B→C is $$+15 kJ$$, what is the free energy change for the overall pathway A→C?

Accepted Answer

$$-5 kJ$$

Question 8

Why do cells couple exergonic and endergonic reactions?

Accepted Answer

To use the energy released from exergonic reactions to drive endergonic reactions that would not occur spontaneously.

Question 9

What is the role of ATP in cellular metabolism?

Accepted Answer

ATP acts as an activated carrier, storing and transferring energy to power endergonic reactions.

Question 10

Which of the following best describes the function of an enzyme?

Accepted Answer

An enzyme lowers the activation energy required for a reaction, increasing the rate without being consumed.

Question 11

Which statement correctly describes competitive inhibition?

Accepted Answer

A competitive inhibitor binds to the active site of an enzyme, preventing substrate binding.

Question 12

What is an allosteric site on an enzyme?

Accepted Answer

A site other than the active site where a molecule can bind and regulate enzyme activity.

Question 13

Which of the following is a correct example of feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 14

Which of the following is NOT a function of an activated carrier like ATP?

Accepted Answer

Serving as a structural component of DNA.

Question 15

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzymes are highly specific, usually catalyzing only one type of reaction for a particular substrate.

Question 16

Which of the following is a correct description of entropy ($$S) in $$biological systems?

Accepted Answer

Entropy is a measure of disorder; catabolic reactions increase entropy by breaking down molecules.

Question 17

A drug inhibits an enzyme by binding to a site other than the active site, causing a conformational change. What type of inhibition is this?

Accepted Answer

Non-competitive inhibition

Question 18

Which of the following is true about the energy of a metabolic pathway?

Accepted Answer

The total free energy change of a pathway is the sum of the free energy changes of each step.

Question 19

Which of the following is a real-life example of coupling exergonic and endergonic reactions in cells?

Accepted Answer

Using the energy released from glucose oxidation to synthesize ATP.

Question 20

Which of the following is a correct statement about spontaneous processes in cells?

Accepted Answer

A spontaneous process has a negative $$\Delta G$$ and can be harnessed by the cell to do work.

ch.8 Metabolic Pathways, Energy, and Enzyme Regulation in Cells

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