Q: A chemical reaction has a change in enthalpy $$\Delta H = -100 kJ/$$mol, a change in entropy $$\Delta S = 0.2 kJ/($$mol\cdot K), and occurs at $$T = 300 K. $$What is the change in free energy $$\Delta G$$ for this reaction?

$$\Delta G = -100 - (300 \times 0.2) = -100 - 60 = -160 kJ/$$mol

Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in metabolism?

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules, whereas anabolic pathways consume energy to build complex molecules.

Question 2

According to the first law of thermodynamics, which of the following statements is correct?

Accepted Answer

Energy can be transferred or transformed, but cannot be created or destroyed.

Question 3

A chemical reaction has a change in enthalpy $$\Delta H = -100 kJ/$$mol, a change in entropy $$\Delta S = 0.2 kJ/($$mol\cdot K), and occurs at $$T = 300 K. $$What is the change in free energy $$\Delta G$$ for this reaction?

Accepted Answer

$$\Delta G = -100 - (300 	imes 0.2) = -100 - 60 = -160 kJ/$$mol

Question 4

Which of the following best explains why living cells are considered open systems?

Accepted Answer

They constantly exchange energy and matter with their environment, preventing equilibrium.

Question 5

Which of the following statements about ATP is correct?

Accepted Answer

ATP hydrolysis releases energy that can be used to drive endergonic reactions in the cell.

Question 6

A scientist is studying an enzyme-catalyzed reaction. She increases the temperature from 25°C to 60°C and observes that the reaction rate first increases, then sharply decreases. What is the most likely explanation for the decrease in reaction rate at higher temperature?

Accepted Answer

The enzyme denatures at temperatures above its optimal range.

Question 7

Which of the following is true regarding the effect of enzymes on chemical reactions?

Accepted Answer

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

Question 8

A metabolic pathway is regulated by feedback inhibition. Which of the following best describes this process?

Accepted Answer

The end product of the pathway inhibits an enzyme that acts early in the pathway.

Question 9

Which of the following is an example of a competitive inhibitor?

Accepted Answer

A molecule that binds to the active site of an enzyme, preventing substrate binding.

Question 10

Which of the following best describes the role of phosphorylation in energy coupling?

Accepted Answer

Phosphorylation transfers a phosphate group from ATP to another molecule, making the recipient more reactive.

Question 11

Which of the following equations correctly represents the relationship between free energy, enthalpy, entropy, and temperature?

Accepted Answer

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

Question 12

A reaction has $$\Delta G \u003c 0. $$Which of the following statements is true?

Accepted Answer

The reaction is spontaneous and can perform work.

Question 13

Which of the following is a function of allosteric regulation in enzymes?

Accepted Answer

It can either inhibit or stimulate enzyme activity by binding to a site other than the active site.

Question 14

Which of the following best explains why metabolic reactions in living cells do not reach equilibrium?

Accepted Answer

Cells constantly remove products and add reactants, keeping reactions away from equilibrium.

Question 15

Which of the following is NOT a way that enzymes lower activation energy ($$E_a$$)?

Accepted Answer

Increasing the free energy change ($$\Delta G) of $$the reaction.

Question 16

A patient is given a drug that acts as a noncompetitive inhibitor of a key metabolic enzyme. What is the most likely effect of this drug?

Accepted Answer

It binds to a site other than the active site, reducing enzyme activity regardless of substrate concentration.

Question 17

Which of the following best describes the ATP cycle in cells?

Accepted Answer

ATP is synthesized from ADP and phosphate using energy from catabolic reactions, and hydrolyzed to provide energy for cellular work.

Question 18

Which of the following is an example of an exergonic reaction in a biological system?

Accepted Answer

Hydrolysis of ATP to ADP and inorganic phosphate.

Question 19

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is determined by the shape of the active site and the substrate.

Question 20

A mutation causes an enzyme to lose its ability to bind its cofactor. What is the most likely consequence?

Accepted Answer

The enzyme will lose its catalytic activity.

Chapter 8: An Introduction to Metabolism (Campbell Biology)

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드