Question 1

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

Accepted Answer

Energy is transferred and transformed, but cannot be created or destroyed.

Question 2

A reaction has a $$\Delta G of$$ $$-30\ 	ext{kJ/mol}. $$What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 3

Which of the following is a correct description of ATP’s role in cellular energy coupling?

Accepted Answer

ATP hydrolysis releases energy that can drive endergonic reactions.

Question 4

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

Accepted Answer

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

Question 5

Which of the following best explains why enzymes are necessary for biological reactions?

Accepted Answer

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

Question 6

A scientist increases the temperature of an enzyme-catalyzed reaction. What is the most likely effect if the temperature exceeds the enzyme’s optimal range?

Accepted Answer

The enzyme will denature, losing its structure and function.

Question 7

Which of the following is NOT a mechanism by which enzymes lower activation energy?

Accepted Answer

Directly increasing the $$\Delta G of $$the reaction.

Question 8

Which statement best describes the effect of competitive inhibitors on enzyme activity?

Accepted Answer

They bind to the active site, preventing substrate binding.

Question 9

Which of the following is evidence for the common ancestry of all organisms?

Accepted Answer

Conservation of core metabolic pathways such as glycolysis.

Question 10

If an enzyme is saturated with substrate, what is the effect of adding more substrate?

Accepted Answer

The reaction rate will remain unchanged.

Question 11

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

Accepted Answer

The enzyme changes shape to fit the substrate upon binding.

Question 12

Which of the following is true about the hydrolysis of ATP?

Accepted Answer

It releases energy by breaking a phosphate bond.

Question 13

Which of the following would most likely cause permanent denaturation of an enzyme?

Accepted Answer

Extreme changes in pH.

Question 14

Which term describes a metabolic pathway that breaks down molecules and releases energy?

Accepted Answer

Catabolic pathway

Question 15

Which of the following is a coenzyme?

Accepted Answer

NAD+

Question 16

Which of the following best describes the second law of thermodynamics?

Accepted Answer

Every energy transfer increases the entropy of the universe.

Question 17

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

Accepted Answer

Using ATP hydrolysis to drive the synthesis of glutamine from glutamic acid and ammonia.

Question 18

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzymes are specific because their active sites fit only certain substrates.

Question 19

Which of the following is true about noncompetitive inhibitors?

Accepted Answer

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

Question 20

Which of the following best describes the transition state in an enzyme-catalyzed reaction?

Accepted Answer

It is the unstable intermediate with the highest energy.

Energy and Enzymes: Metabolic Pathways and Cellular Work

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