Question 1

Which of the following best describes a metabolic pathway?

Accepted Answer

A series of chemical reactions, each catalyzed by a specific enzyme, that begins with a specific molecule and ends with a product.

Question 2

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

Accepted Answer

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

Question 3

A diver climbs to the top of a platform and then jumps into the water. Which forms of energy are primarily involved in this scenario?

Accepted Answer

Potential energy is increased while climbing, and is converted to kinetic energy while diving.

Question 4

Which equation correctly represents the change in free energy for a chemical reaction?

Accepted Answer

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

Question 5

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

Accepted Answer

Exergonic reactions release free energy and have a negative $$\Delta G.$$

Question 6

A cell uses ATP hydrolysis to drive an endergonic reaction. Which term best describes this process?

Accepted Answer

Energy coupling

Question 7

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

Accepted Answer

Increasing the temperature of the reaction environment.

Question 8

A patient is given a drug that binds to the active site of an enzyme, preventing the substrate from binding. What type of inhibition is this?

Accepted Answer

Competitive inhibition

Question 9

Which of the following best explains why the hydrolysis of ATP is used to power cellular work?

Accepted Answer

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

Question 10

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

Accepted Answer

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

Question 11

If a reaction has $$\Delta G \u003c 0$$, which of the following is true?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 12

Which of the following is a real-life example of the second law of thermodynamics in biological systems?

Accepted Answer

During cellular respiration, some energy is lost as heat, increasing the entropy of the surroundings.

Question 13

A scientist measures the enthalpy change ($$\Delta H) $$and entropy change ($$\Delta S) $$for a reaction at 298 K. If $$\Delta H = -50 kJ/$$mol and $$\Delta S = -0.1 kJ/($$mol·K), what is $$\Delta G$$ for the reaction?

Accepted Answer

$$ \Delta G = -50 - (298 	imes -0.1) = -50 + 29.8 = -20.2 	ext{ kJ/mol} $$

Question 14

Which of the following statements about allosteric regulation is correct?

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

A mutation causes an enzyme's active site to change shape, so the substrate no longer fits. What is the most likely consequence?

Accepted Answer

The enzyme will lose its catalytic activity.

Question 17

Which of the following is an example of mechanical work performed by ATP in a cell?

Accepted Answer

Movement of a vesicle along a cytoskeletal track by a motor protein.

Question 18

Which of the following is a correct statement about the relationship between entropy and biological order?

Accepted Answer

Biological systems maintain order locally, but increase the entropy of their surroundings.

An Introduction to Metabolism (Chapter 8) – General Biology Study Notes

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