Question 1

Which of the following best describes a catabolic pathway in cellular metabolism?

Accepted Answer

A pathway that breaks down complex molecules into simpler compounds, releasing energy.

Question 2

According to the first law of thermodynamics, which statement is correct?

Accepted Answer

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

Question 3

A cell builds a protein from amino acids. Which type of metabolic pathway and reaction is this?

Accepted Answer

Anabolic pathway; endergonic reaction

Question 4

Which of the following equations correctly represents the change in free energy ($$\Delta G) $$for a system?

Accepted Answer

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

Question 5

Which statement about exergonic reactions is TRUE?

Accepted Answer

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

Question 6

Why does ATP hydrolysis release a large amount of energy?

Accepted Answer

Because the repulsive force between the negatively charged phosphate groups is relieved when a phosphate is removed.

Question 7

A scientist adds a competitive inhibitor to an enzyme-catalyzed reaction. What is the most likely effect?

Accepted Answer

The inhibitor binds to the active site, preventing substrate binding.

Question 8

Which process in metabolism is most directly responsible for maintaining order in living cells despite the second law of thermodynamics?

Accepted Answer

Input of energy from the surroundings, such as light or food

Question 9

Which of the following best explains why enzymes are necessary for metabolic reactions?

Accepted Answer

Enzymes lower the activation energy ($$E_a) $$required for reactions to proceed.

Question 10

A metabolic pathway is regulated by feedback inhibition. What is the role of the end product in this process?

Accepted Answer

It inhibits an enzyme earlier in the pathway, preventing overproduction.

Question 11

Which of the following is an example of energy transformation in living organisms?

Accepted Answer

Conversion of light energy to chemical energy during photosynthesis

Question 12

If a cell reaches equilibrium in its metabolic pathways, what is the consequence?

Accepted Answer

The cell dies because no work can be performed.

Question 13

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity results from the fit between the enzyme's active site and the substrate.

Question 14

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

Accepted Answer

Increasing the temperature of the reaction

Question 15

A cell uses ATP to drive the endergonic synthesis of sucrose. Which process is directly involved?

Accepted Answer

Phosphorylation of an intermediate molecule

Question 16

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

Accepted Answer

Cofactors are non-protein helpers that assist enzymes in catalysis.

Question 17

Which scenario illustrates the second law of thermodynamics in biological systems?

Accepted Answer

A cell organizes molecules into complex structures, decreasing entropy locally but increasing entropy in the universe.

Question 18

Which of the following is true about allosteric regulation of enzymes?

Accepted Answer

A regulatory molecule binds at a site other than the active site, affecting enzyme function.

Question 19

Which of the following is a consequence of enzyme saturation in a reaction?

Accepted Answer

The reaction rate can only be increased by adding more enzyme.

Question 20

Which of the following is a real-world example of feedback inhibition?

Accepted Answer

The end product of a metabolic pathway inhibits an enzyme early in the pathway, such as isoleucine inhibiting threonine deaminase.

Chapter 6: An Introduction to Metabolism – Study Notes

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