Question 1

Which of the following best describes the first law of thermodynamics and its relevance to living organisms?

Accepted Answer

Energy can be transferred and transformed, but cannot be created or destroyed, meaning organisms must obtain energy from their environment to do work.

Question 2

A plant absorbs sunlight and uses it to build glucose molecules. According to the second law of thermodynamics, what must also occur during this process?

Accepted Answer

Some energy is lost as heat, increasing the entropy of the 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

A reaction has $$\Delta G \u003c 0. $$What does this indicate about the reaction?

Accepted Answer

The reaction is spontaneous and can perform work.

Question 5

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

Accepted Answer

The synthesis of proteins from amino acids.

Question 6

ATP hydrolysis is often coupled to endergonic reactions in cells. Which statement best explains why?

Accepted Answer

ATP hydrolysis releases energy, which can be used to drive reactions that require an input of energy.

Question 7

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

Accepted Answer

Enzymes lower the activation energy ($$E_a) $$needed, speeding up the reaction without being consumed.

Question 8

A competitive inhibitor affects an enzyme by:

Accepted Answer

Competing with the substrate for binding at the active site.

Question 9

Which of the following environmental changes is most likely to decrease the rate of an enzyme-catalyzed reaction in a human cell?

Accepted Answer

Lowering the pH from 7.4 to 2.

Question 10

Which of the following statements about feedback inhibition is correct?

Accepted Answer

Feedback inhibition occurs when the end product of a metabolic pathway inhibits an enzyme early in the pathway.

Question 11

A scientist measures the free energy change ($$\Delta G) of a $$reaction and finds it to be positive. What can be concluded about this reaction?

Accepted Answer

The reaction is nonspontaneous and requires an input of energy.

Question 12

Which of the following best illustrates energy coupling in a cell?

Accepted Answer

Using the energy released from ATP hydrolysis to drive the active transport of ions across a membrane.

Question 13

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

Accepted Answer

Changing the overall free energy ($$\Delta G) of $$the reaction.

Question 14

A patient is given a drug that acts as a noncompetitive inhibitor of a key metabolic enzyme. What is the most likely effect of this drug?

Accepted Answer

It binds to a different site on the enzyme, altering its shape and reducing activity.

Question 15

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

Accepted Answer

The enzyme changes shape slightly to better fit the substrate upon binding.

Question 16

Which of the following is an example of catabolic metabolism?

Accepted Answer

The breakdown of triglycerides into fatty acids and glycerol.

Question 17

If a cell's ATP supply is depleted, which of the following processes would be most directly affected?

Accepted Answer

Active transport of sodium ions out of the cell.

Question 18

Which of the following statements about metabolic equilibrium in living cells is correct?

Accepted Answer

A cell at metabolic equilibrium is dead because no work can be done.

Question 19

A mutation causes an enzyme's active site to become less complementary to its substrate. What is the most likely result?

Accepted Answer

The enzyme will bind the substrate less effectively, reducing the reaction rate.

Question 20

Which of the following best explains why high fevers can be dangerous to human health at the molecular level?

Accepted Answer

High temperatures can denature enzymes, disrupting their structure and function.

Chapter 8: Introduction to Metabolism – Laws of Thermodynamics and Biological Energy Transformations

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