Question 1

Which statement best describes the First Law of Thermodynamics as it applies to living cells?

Accepted Answer

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

Question 2

A cell uses ATP to drive the synthesis of proteins. This is an example of which type of metabolic pathway?

Accepted Answer

Anabolic pathway

Question 3

Which of the following best explains why enzymes are considered catalysts?

Accepted Answer

They lower the activation energy and are not permanently changed by the reaction.

Question 4

A chemical reaction in a cell requires an input of energy and is not spontaneous. What type of reaction is this?

Accepted Answer

Endergonic reaction

Question 5

Which of the following is true about chemical equilibrium in a reversible reaction?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction.

Question 6

If a competitive inhibitor is added to a reaction, which of the following will most likely increase the rate of product formation?

Accepted Answer

Increasing the concentration of the substrate.

Question 7

Which equation correctly represents the relationship between activation energy ($E_a$), free energy of reactants ($G_r$), and free energy of products ($G_p$) in an exergonic reaction?

Accepted Answer

$E_a$ is the energy required to reach the transition state from $G_r$

Question 8

Which of the following would most likely decrease the activity of an enzyme in a human cell?

Accepted Answer

Changing the pH away from the enzyme's optimum.

Question 9

A metabolic pathway is regulated by feedback inhibition. Which of the following best describes this process?

Accepted Answer

The end product of the pathway inhibits an enzyme earlier in the pathway.

Question 10

Which statement about noncompetitive inhibitors is correct?

Accepted Answer

They bind at a site remote from the active site and change the enzyme's shape.

Question 11

Which of the following best describes entropy ($S$) in biological systems?

Accepted Answer

Entropy is the measure of disorder or randomness.

Question 12

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

Accepted Answer

Breakdown of glucose during cellular respiration.

Question 13

Which of the following is true about the specificity of enzymes?

Accepted Answer

Enzymes have active sites that fit specific substrates.

Question 14

A scientist increases the substrate concentration in a reaction with a competitive inhibitor present. What is the expected effect?

Accepted Answer

The substrate will outcompete the inhibitor, increasing reaction rate.

Question 15

Which of the following best describes the role of coenzymes in enzymatic reactions?

Accepted Answer

Coenzymes are small organic molecules required for proper enzyme function.

Question 16

Which of the following is an example of a coupled reaction in biological systems?

Accepted Answer

The breakdown of glucose releases energy that is used to synthesize ATP.

Question 17

Which of the following is true about activation energy ($E_a$) in chemical reactions?

Accepted Answer

Activation energy is the energy required to start a reaction.

Question 18

Which of the following would most likely occur if the temperature of a human enzyme is raised far above its optimum?

Accepted Answer

The enzyme would denature and lose its activity.

Question 19

Which of the following best describes the difference between open and closed systems in thermodynamics?

Accepted Answer

Closed systems can exchange energy but not matter with their surroundings.

Question 20

Which of the following is most likely to occur during an exergonic reaction in a cell?

Accepted Answer

Energy is released and can be used to do cellular work.

Energy Flow and Enzyme Function in the Life of a Cell

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