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

A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This observation best illustrates which biological principle?

Accepted Answer

the second law of thermodynamics

Question 2

When a cell uses chemical energy to perform work, it couples the energy released from a(n) ________ reaction to drive a(n) ________ reaction.

Accepted Answer

exergonic; endergonic

Question 3

Which of the following best describes the effect of an enzyme on a chemical reaction?

Accepted Answer

It lowers the activation energy of the reaction.

Question 4

Substrates bind to which part of an enzyme?

Accepted Answer

active site

Question 5

Which of the following statements about enzyme function is FALSE?

Accepted Answer

Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction.

Question 6

Heating inactivates enzymes by which mechanism?

Accepted Answer

changing the enzyme's three-dimensional shape by breaking the peptide bonds

Question 7

Bacterial production of enzymes for tryptophan synthesis declines with increasing tryptophan levels and increases as tryptophan levels decline. This is an example of:

Accepted Answer

feedback inhibition

Question 8

How does inhibition of an enzyme-catalyzed reaction by a competitive inhibitor differ from inhibition by a noncompetitive inhibitor?

Accepted Answer

Competitive inhibitors bind to the active site of the enzyme; noncompetitive inhibitors bind to an allosteric site.

Question 9

Which of the following processes is endergonic?

Accepted Answer

the synthesis of glucose from carbon dioxide and water

Question 10

Refer to the reaction progress diagram (second image). Which of the following would be the same in both an enzyme-catalyzed and a noncatalyzed reaction?

Accepted Answer

$$c$$

Question 11

Refer to the reaction progress diagram (second image). Which of the following represents the activation energy required for the non-enzyme-catalyzed reaction?

Accepted Answer

$$a$$

Question 12

Which part of the ATP molecule breaks free when ATP is hydrolyzed to release energy, as shown in the first image?

Accepted Answer

part D

Question 13

A patient is given a drug that acts as a noncompetitive inhibitor for a key metabolic enzyme. What is the most likely effect on the enzyme's activity?

Accepted Answer

The enzyme's activity will decrease because the inhibitor binds to an allosteric site, altering the enzyme's shape.

Question 14

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 15

Which of the following best explains why energy transformations are not 100% efficient in living systems?

Accepted Answer

Some energy is converted to heat, increasing entropy.

Question 16

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely outcome?

Accepted Answer

The inhibitor binds to the active site, preventing substrate binding.

Question 17

Which of the following scenarios best illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

A product of the pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 18

Which of the following is an example of an exergonic reaction?

Accepted Answer

Cellular respiration

Question 19

If the activation energy of a reaction is lowered, what is the most likely effect on the reaction rate?

Accepted Answer

The reaction rate will increase.

Question 20

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

Accepted Answer

ATP provides energy for cellular work by transferring a phosphate group.

Study Guide: Enzymes & Energy (Bio 121, Chapter 5)

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