Question 1

Which statement best describes the difference between kinetic and potential energy in biological systems?

Accepted Answer

Kinetic energy is the energy of motion, such as thermal energy, while potential energy is stored in the position or configuration of molecules, such as chemical energy in bonds.

Question 2

During a chemical reaction, the products often have shorter, stronger covalent bonds than the reactants. What does this imply about the potential energy of the products compared to the reactants?

Accepted Answer

The products have lower potential energy than the reactants.

Question 3

Which equation correctly represents the standard free-energy change for a chemical reaction?

Accepted Answer

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

Question 4

A reaction is considered spontaneous if which of the following is true?

Accepted Answer

$$\Delta G \u003c 0$$

Question 5

Which of the following best explains why increasing temperature generally increases the rate of a chemical reaction?

Accepted Answer

Higher temperature increases the number of collisions between reactant molecules, providing more kinetic energy to overcome activation energy.

Question 6

In cells, energetic coupling allows endergonic reactions to proceed by using energy from exergonic reactions. Which of the following is NOT a common mechanism for energetic coupling?

Accepted Answer

Direct transfer of heat from one reaction to another.

Question 7

Which statement about redox reactions is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 8

Which molecule acts as an electron carrier by accepting two electrons and two protons to form its reduced state?

Accepted Answer

FADH$$_2$$

Question 9

ATP hydrolysis releases energy that can be used to drive endergonic reactions. What is the main reason ATP has such high potential energy?

Accepted Answer

It forms bonds between three negatively charged phosphate groups, which repel each other.

Question 10

Which of the following best describes how enzymes lower the activation energy of a reaction?

Accepted Answer

Enzymes bring substrates together in precise orientations and stabilize the transition state.

Question 11

What is the role of the induced fit in enzyme catalysis?

Accepted Answer

It results in a conformational change in the enzyme that helps substrates bind more tightly and reach the transition state.

Question 12

Which of the following statements about enzyme saturation kinetics is correct?

Accepted Answer

At high substrate concentrations, the reaction rate plateaus because all enzyme active sites are occupied.

Question 13

Which of the following is NOT a type of molecule that can assist enzyme function?

Accepted Answer

Polysaccharides

Question 14

How does pH affect enzyme activity?

Accepted Answer

It changes the charge on acidic and basic groups, affecting enzyme shape and reactivity.

Question 15

Which regulatory mechanism involves a molecule binding to an enzyme at a site other than the active site, causing a change in enzyme shape?

Accepted Answer

Allosteric regulation

Question 16

Phosphorylation is a common reversible modification of enzymes. What is its primary effect?

Accepted Answer

It changes the enzyme's shape, which can activate or deactivate its function.

Question 17

In a metabolic pathway, feedback inhibition occurs when:

Accepted Answer

The final product inhibits an enzyme earlier in the pathway.

Question 18

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

Accepted Answer

Catabolic pathways break down molecules for energy and carbon building blocks, while anabolic pathways use energy and carbon building blocks to synthesize molecules.

Question 19

A patient with nonalcoholic fatty liver disease is found to have altered metabolic activity in their intestinal microbiota. Which of the following could explain an increased risk of obesity based on bacterial metabolism?

Accepted Answer

Increased anabolic activity in bacteria leading to synthesis of energy-rich molecules.

Question 20

Which of the following is true regarding the evolution of metabolic pathways?

Accepted Answer

Metabolic pathways evolve by recruiting new enzymes to existing pathways and by retro-evolution when substrates decline.

Chapter 8: Energy and Enzymes – An Introduction to Metabolism (General Biology Study Notes)

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