Question 1

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

Accepted Answer

Energy can be transformed from one form to another, but it cannot be created or destroyed.

Question 2

A plant uses sunlight to synthesize glucose, and a termite later digests the plant material. According to the second law of thermodynamics, what must occur during these energy transformations?

Accepted Answer

Some energy is lost as heat at each transformation, increasing the entropy of the surroundings.

Question 3

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

Accepted Answer

The synthesis of protein from amino acids.

Question 4

A diver climbs up a platform, converting chemical energy from food into kinetic energy of movement, and then into potential energy. Which equation best represents the conservation of energy in this scenario?

Accepted Answer

$$E_{chemical} = E_{kinetic} + E_{potential} + E_{heat}$$

Question 5

Which statement about enzymes is correct?

Accepted Answer

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

Question 6

A patient is diagnosed with a genetic disorder that results in a nonfunctional enzyme in a metabolic pathway. Which of the following is the most likely consequence?

Accepted Answer

The specific substrate for the defective enzyme will accumulate, and the product will not be formed.

Question 7

Which of the following best explains why ATP is considered the 'energy currency' of the cell?

Accepted Answer

ATP hydrolysis releases energy that can be coupled to endergonic reactions.

Question 8

Which of the following scenarios illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

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

Question 9

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect on the reaction rate, and how can it be overcome?

Accepted Answer

The reaction rate will decrease, but increasing substrate concentration can restore the rate.

Question 10

Which of the following best describes the role of cofactors in enzyme activity?

Accepted Answer

Cofactors are nonprotein helpers that are required for some enzymes to function properly.

Question 11

A researcher finds that an enzyme from a thermophilic bacterium has an optimal temperature of 75°C. What would most likely happen to the enzyme's activity at 37°C?

Accepted Answer

The enzyme's activity would decrease significantly.

Question 12

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

Accepted Answer

Enzymes recognize and bind to specific substrates due to the complementary fit of the active site.

Question 13

Which of the following best explains why the hydrolysis of ATP is exergonic?

Accepted Answer

The chemical change to a state of lower free energy in the products releases energy.

Question 14

A noncompetitive inhibitor decreases the rate of an enzyme-catalyzed reaction by:

Accepted Answer

Binding to a site other than the active site, causing a conformational change in the enzyme.

Question 15

Which of the following equations correctly represents the ATP cycle in cells?

Accepted Answer

$$ATP \xrightarrow{hydrolysis} ADP + P_i + energy$$ and $$ADP + P_i + energy \xrightarrow{phosphorylation} ATP$$

Question 16

Which of the following is a real-life example of an exergonic reaction in human cells?

Accepted Answer

The hydrolysis of ATP to ADP and inorganic phosphate.

Question 17

A person takes a vitamin supplement that acts as a coenzyme. What is the most likely effect on their metabolism?

Accepted Answer

The vitamin will help certain enzymes function more efficiently.

Question 18

Which of the following best describes the effect of temperature on enzyme activity?

Accepted Answer

Each enzyme has an optimal temperature at which it functions most efficiently.

Question 19

In a metabolic pathway, what is the most likely result if the product of the pathway accumulates and inhibits the first enzyme in the pathway?

Accepted Answer

The pathway will slow down or stop, preventing overproduction of the product.

Introduction to Metabolism: Energy and Enzymes in Biological Systems

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