Question 1

Which of the following statements best describes the first law of thermodynamics as it applies to living organisms?

Accepted Answer

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

Question 2

A cell is considered an open system because:

Accepted Answer

It continuously exchanges both energy and matter with its surroundings.

Question 3

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 4

Which of the following is true about exergonic reactions?

Accepted Answer

They release free energy and have a negative $$\Delta G$$ value.

Question 5

ATP hydrolysis is often coupled to endergonic reactions in cells. What is the net effect of this coupling?

Accepted Answer

The overall process becomes exergonic, allowing the endergonic reaction to proceed.

Question 6

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

Accepted Answer

The active site of an enzyme has a unique shape and chemical environment that fits only specific substrates.

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 statements about activation energy ($$E_a) is $$correct?

Accepted Answer

Activation energy is the initial energy required to start a chemical reaction.

Question 9

In feedback inhibition, the end product of a metabolic pathway:

Accepted Answer

Binds to an enzyme early in the pathway and inhibits its activity.

Question 10

Which of the following is an example of potential energy in a biological system?

Accepted Answer

The energy stored in the chemical bonds of glucose.

Question 11

Why do reactions in a closed system eventually reach equilibrium and stop doing work?

Accepted Answer

Because the concentrations of reactants and products become equal, and no net change occurs.

Question 12

Which of the following is NOT a way that enzymes lower the activation energy ($$E_a) of a $$reaction?

Accepted Answer

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

Question 13

A metabolic pathway that builds complex molecules from simpler ones is called:

Accepted Answer

Anabolic

Question 14

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

Accepted Answer

ATP couples exergonic and endergonic reactions, providing energy for cellular processes.

Question 15

Which of the following is true about entropy in biological systems?

Accepted Answer

Cells decrease their own entropy by creating order, but increase the entropy of their surroundings.

Question 16

Which of the following is an example of allosteric regulation?

Accepted Answer

A regulatory molecule binding to a site other than the active site, changing enzyme activity.

Question 17

If the free energy change ($$\Delta G) $$for a reaction is positive, which of the following is true?

Accepted Answer

The reaction is nonspontaneous and requires an input of energy.

Question 18

Which of the following statements about enzyme saturation is correct?

Accepted Answer

At saturation, all enzyme active sites are occupied and the reaction rate levels off.

Question 19

Which of the following is a real-world example of energy transformation in biological systems?

Accepted Answer

A bear converting chemical energy from food into kinetic energy for running.

Question 20

Which of the following statements about cofactors is true?

Accepted Answer

Cofactors are nonprotein helpers required for some enzymes to function.

Metabolism and Enzyme Function: Principles of Energy and Regulation in Cells

Study Guide - Practice Questions