Q: Which equation correctly represents the hydrolysis of ATP?

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$$

Question 1

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

Accepted Answer

Energy is transferred and transformed, but the total amount of energy in the universe remains constant.

Question 2

A cell breaks down glucose in a series of reactions. Which of the following best describes the change in free energy ($$\Delta G) $$during cellular respiration?

Accepted Answer

$$\Delta G is $$negative because energy is released and the process is exergonic.

Question 3

Which of the following reactions is considered endergonic?

Accepted Answer

Synthesis of glucose from carbon dioxide and water during photosynthesis

Question 4

Which equation correctly represents the hydrolysis of ATP?

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy}$$

Question 5

Which of the following best explains why enzymes are necessary for metabolic reactions in cells?

Accepted Answer

Enzymes lower the activation energy ($$E_a$$), allowing reactions to occur at cellular temperatures.

Question 6

Which of the following is an example of energy coupling in cells?

Accepted Answer

Using the energy released from ATP hydrolysis to drive the active transport of ions across a membrane

Question 7

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the active site and preventing substrate binding

Question 8

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

Accepted Answer

Raising the temperature above the enzyme's optimal range

Question 9

Which statement about allosteric regulation is correct?

Accepted Answer

Allosteric regulators bind to sites other than the active site, changing enzyme activity.

Question 10

Which of the following best describes the effect of an enzyme on the activation energy ($$E_a) $$and free energy change ($$\Delta G) of a $$reaction?

Accepted Answer

Enzymes lower $$E_a$$ but do not change $$\Delta G.$$

Question 11

Which of the following is a coenzyme?

Accepted Answer

NAD+

Question 12

A reaction has $$\Delta G = +3.5$$ kcal/mol. Which statement is true?

Accepted Answer

The reaction is endergonic and requires energy input.

Question 13

Which of the following is NOT a way enzymes lower activation energy?

Accepted Answer

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

Question 14

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP acts as an energy currency, coupling exergonic and endergonic reactions.

Question 15

Which of the following is an example of feedback inhibition in metabolic pathways?

Accepted Answer

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

Question 16

Which of the following statements about noncompetitive inhibitors is correct?

Accepted Answer

They bind to a site other than the active site and change the enzyme's shape.

Question 17

Which of the following best explains why extremes of pH can denature enzymes?

Accepted Answer

pH changes can disrupt hydrogen bonds and ionic interactions, altering the enzyme's tertiary structure.

Question 18

Which of the following is true about the induced fit model of enzyme action?

Accepted Answer

The enzyme changes shape slightly to fit the substrate more closely upon binding.

Question 19

Which of the following is a real-world example of an enzyme functioning at low pH?

Accepted Answer

Pepsin in the human stomach

Chapter 8: An Introduction to Metabolism – Study Guide and Key Concepts

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