Question 1

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

Accepted Answer

Energy can be transferred or transformed, but not created or destroyed.

Question 2

A hydroelectric dam stores water at a high elevation. When the water is released, it turns turbines to generate electricity. Which type of energy transformation is primarily occurring as the water falls and spins the turbines?

Accepted Answer

Potential energy to kinetic energy

Question 3

Which equation correctly relates the change in free energy ($$\Delta G) to $$enthalpy ($$\Delta H$$), entropy ($$\Delta S$$), and temperature ($$T) in a $$biological system?

Accepted Answer

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

Question 4

Which of the following statements about enzymes is TRUE?

Accepted Answer

Enzymes lower the activation energy barrier, allowing reactions to occur more rapidly.

Question 5

A bear eats a fish and uses the energy to swim. According to the second law of thermodynamics, what happens to some of the energy from the fish?

Accepted Answer

It is lost as heat, increasing the entropy of the surroundings.

Question 6

Which of the following best explains why cells must remain open systems and never reach metabolic equilibrium?

Accepted Answer

Open systems allow continuous flow of materials, preventing equilibrium and enabling work.

Question 7

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

Accepted Answer

The use of ATP hydrolysis (exergonic) to drive the synthesis of proteins (endergonic).

Question 8

Which of the following statements about ATP is FALSE?

Accepted Answer

ATP hydrolysis is an endergonic reaction under cellular conditions.

Question 9

Which of the following best describes the role of a competitive inhibitor?

Accepted Answer

It binds to the enzyme's active site, blocking substrate binding.

Question 10

A mutation changes the amino acid sequence at the active site of an enzyme. Which of the following is a possible outcome?

Accepted Answer

The enzyme may gain a new substrate specificity.

Question 11

Which of the following is an example of feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of a pathway binds to an enzyme early in the pathway, decreasing its activity.

Question 12

Which of the following best explains why increasing temperature beyond the optimal range decreases enzyme activity?

Accepted Answer

The enzyme denatures, losing its functional shape.

Question 13

Which of the following is TRUE about the difference between catabolic and anabolic pathways?

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules; anabolic pathways consume energy to build complex molecules.

Question 14

Which of the following is a correct statement about exergonic and endergonic reactions?

Accepted Answer

Exergonic reactions have $$\Delta G  0$$ and require energy input.

Question 15

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

Accepted Answer

Supplying heat to the reaction

Question 16

Which of the following best describes allosteric regulation of an enzyme?

Accepted Answer

A regulatory molecule binds to a site other than the active site, changing the enzyme's activity.

Question 17

Which of the following is an example of a coenzyme?

Accepted Answer

Vitamin B$$_6$$

Question 18

Which of the following scenarios best illustrates the concept of induced fit in enzyme activity?

Accepted Answer

The enzyme changes shape slightly to better fit the substrate after the substrate binds.

Question 19

Which of the following statements about spontaneous processes is correct?

Accepted Answer

Spontaneous processes occur without energy input and have $$\Delta G \u003c 0.$$

Ch 8

Study Guide - Practice Questions

Study Guide - Flashcards