Question 1

Which of the following best describes the difference between catabolic and anabolic pathways in metabolism?

Accepted Answer

Catabolic pathways break down complex molecules and release energy, while anabolic pathways build complex molecules and require energy.

Question 2

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

Accepted Answer

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

Question 3

A chemical reaction has a $$\Delta G of$$ $$-10$$ kcal/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and occurs spontaneously.

Question 4

Which of the following best explains why ATP hydrolysis is used to drive endergonic reactions in cells?

Accepted Answer

ATP hydrolysis releases energy that can be coupled to endergonic reactions, making the overall process exergonic.

Question 5

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

Accepted Answer

A molecule of glucose before it is broken down in cellular respiration.

Question 6

What is the main function of enzymes in biological systems?

Accepted Answer

To speed up the rate of spontaneous reactions by lowering the activation energy.

Question 7

A scientist observes that an enzyme-catalyzed reaction proceeds much faster at pH 7 than at pH 4 or pH 10. What is the most likely explanation?

Accepted Answer

The enzyme has an optimal pH near 7, and extreme pH values disrupt its structure.

Question 8

Which of the following scenarios best illustrates 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 9

Which of the following statements about entropy is correct?

Accepted Answer

Entropy increases as a system becomes more disordered.

Question 10

A reaction in a cell has a positive $$\Delta G. $$Which of the following is most likely true?

Accepted Answer

The reaction is endergonic and requires an input of energy to proceed.

Question 11

Which of the following best describes the role of a phosphorylated intermediate in a coupled reaction?

Accepted Answer

It is an unstable molecule that allows an endergonic reaction to proceed by making it more exergonic.

Question 12

Which of the following is NOT a way that enzymes lower the activation energy of a reaction?

Accepted Answer

Changing the $$\Delta G of $$the reaction.

Question 13

A patient has a genetic mutation that causes one of their metabolic enzymes to be permanently active, regardless of cellular conditions. What is a likely consequence?

Accepted Answer

The pathway may produce too much product, potentially harming the cell.

Question 14

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

Accepted Answer

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

Question 15

Which of the following is an example of cooperativity in enzyme regulation?

Accepted Answer

The binding of one substrate molecule increases the affinity of the enzyme for additional substrate molecules.

Question 16

Which of the following would most likely increase the rate of an enzyme-catalyzed reaction that is already saturated with substrate?

Accepted Answer

Add more enzyme to the reaction.

Question 17

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

Accepted Answer

The active site of the enzyme has a unique shape that fits only specific substrates.

Question 18

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

Accepted Answer

The hydrolysis of ATP to ADP and phosphate.

Question 19

A cell is exposed to a noncompetitive inhibitor. What is the most likely effect on the enzyme's activity?

Accepted Answer

The inhibitor will bind to a different site, causing a shape change that reduces enzyme activity.

Question 20

Which of the following best describes the ATP cycle in cells?

Accepted Answer

ATP is synthesized from ADP and phosphate using energy from catabolic reactions, and hydrolyzed to release energy for cellular work.

Chapter 6: An Introduction to Metabolism – General Biology Study Notes

Guida di studio - Domande di pratica

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