$$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy}$$

Question 1

Which of the following statements best describes the first law of thermodynamics as it applies to biological systems?

Accepted Answer

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

Question 2

A chemical reaction has a change in free energy $$\Delta G = -30 	ext{ kJ/mol}. $$What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and releases energy.

Question 3

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

Accepted Answer

Movement of cilia on a cell surface.

Question 4

During cellular respiration, which of the following best describes the overall reaction?

Accepted Answer

$$	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6	ext{O}_2 ightarrow 6	ext{CO}_2 + 6	ext{H}_2	ext{O} + 	ext{energy}$$

Question 5

Which of the following processes is considered anabolic?

Accepted Answer

Synthesis of proteins from amino acids.

Question 6

What is the primary role of ATP in cellular metabolism?

Accepted Answer

To couple exergonic and endergonic reactions by providing energy.

Question 7

Which bond in the ATP molecule is most likely to break during hydrolysis, releasing energy?

Accepted Answer

The bond between the second and third phosphate groups.

Question 8

Enzymes speed up chemical reactions by:

Accepted Answer

Lowering the activation energy ($$E_a) $$required for the reaction.

Question 9

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 10

A competitive inhibitor differs from a noncompetitive inhibitor in that:

Accepted Answer

A competitive inhibitor binds to the active site, while a noncompetitive inhibitor binds elsewhere on the enzyme.

Question 11

Which of the following factors would most likely increase the rate of an enzyme-catalyzed reaction?

Accepted Answer

Increasing substrate concentration (up to saturation).

Question 12

Which of the following is an example of a coenzyme?

Accepted Answer

NAD$$^+ ($$nicotinamide adenine dinucleotide)

Question 13

Which of the following best describes the induced fit model of enzyme action?

Accepted Answer

The enzyme changes shape slightly when the substrate binds, creating a tighter fit.

Question 14

Which of the following mechanisms is NOT used by enzymes to lower activation energy?

Accepted Answer

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

Question 15

Pepsin is a human enzyme that functions well at pH 2. Where is it found?

Accepted Answer

In the stomach.

Question 16

Which of the following statements about equilibrium in a chemical reaction is correct?

Accepted Answer

At equilibrium, there is no net flow of energy to do work.

Question 17

Which of the following is true about catabolic pathways?

Accepted Answer

They release energy by breaking down complex molecules.

Question 18

If the activation energy ($$E_a) of a $$reaction is lowered, what is the most likely effect?

Accepted Answer

The reaction rate will increase.

Question 19

Which of the following best describes the role of a phosphorylated intermediate in cellular metabolism?

Accepted Answer

It is a molecule that has gained a phosphate group from ATP, making it more reactive.

Question 20

Which of the following is true about exergonic reactions?

Accepted Answer

They release free energy and have a negative $$\Delta G.$$

Chapter 6: An Introduction to Metabolism – Energy, Enzymes, and Cellular Work

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