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 and transformed, but it cannot be created or destroyed.

Question 2

A metabolic pathway in a cell involves several steps, each catalyzed by a different enzyme. What would most likely happen if the enzyme for the second step is nonfunctional?

Accepted Answer

The pathway would stop at the first step, and the product of the first reaction would accumulate.

Question 3

Which of the following is an example of an anabolic pathway?

Accepted Answer

The synthesis of protein from amino acids.

Question 4

Which equation correctly represents the change in free energy ($$\Delta G) $$for a chemical reaction?

Accepted Answer

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

Question 5

A reaction has $$\Delta G = -20 kJ/$$mol. Which of the following is true about this reaction?

Accepted Answer

It is exergonic and will occur spontaneously.

Question 6

Which of the following best explains why living organisms do not violate the second law of thermodynamics?

Accepted Answer

They increase the entropy of their surroundings through metabolic processes.

Question 7

Which of the following statements about ATP is correct?

Accepted Answer

ATP releases energy when its terminal phosphate bond is broken by hydrolysis.

Question 8

Which of the following is an example of energy coupling in a cell?

Accepted Answer

The hydrolysis of ATP to ADP and $$P_i$$ powers the active transport of ions across a membrane.

Question 9

Which of the following best describes the role of enzymes in biological reactions?

Accepted Answer

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

Question 10

A competitive inhibitor of an enzyme will:

Accepted Answer

Bind to the active site, preventing the substrate from binding.

Question 11

Which of the following environmental changes is most likely to denature an enzyme found in the human stomach?

Accepted Answer

Raising the pH from 2 to 8.

Question 12

Which of the following is true about noncompetitive enzyme inhibitors?

Accepted Answer

They bind to a different site on the enzyme, causing a conformational change.

Question 13

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

Accepted Answer

ATP is synthesized from ADP and $$P_i$$ using energy from catabolic reactions, and hydrolyzed to ADP and $$P_i to $$power cellular work.

Question 14

A reaction in a cell has $$\Delta G = +5$$ kcal/mol. Which of the following is most likely to occur?

Accepted Answer

The reaction will require an input of energy, such as from ATP hydrolysis.

Question 15

Which of the following is NOT a function of ATP in the cell?

Accepted Answer

Storing genetic information.

Question 16

Which of the following best explains why enzymes are highly specific for their substrates?

Accepted Answer

The active site of the enzyme has a complementary shape to the substrate.

Question 17

Which of the following is an example of a catabolic pathway?

Accepted Answer

The breakdown of proteins into amino acids.

Question 18

A cell is exposed to a toxin that irreversibly binds to the active site of an essential enzyme. What is the most likely consequence?

Accepted Answer

The enzyme will be permanently inactivated, and the metabolic pathway will be blocked.

Question 19

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

Accepted Answer

The enzyme changes shape slightly to fit more snugly around the substrate.

Question 20

Which of the following statements about cofactors is correct?

Accepted Answer

Cofactors can be either inorganic ions or organic molecules called coenzymes.

Chapter 8: An Introduction to Metabolism – Study Notes

Study Guide - Practice Questions

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