Q: A reaction has $$\Delta H = -10 kJ/$$mol and $$\Delta S = +0.05 kJ/($$mol\cdot K)$$ at T = 300 K. $$What is $$\Delta G$$ and is the reaction spontaneous?

$$\Delta G = -10 - (300 \times 0.05) = -25 kJ/$$mol; spontaneous

Question 1

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

Accepted Answer

Catabolic pathways release energy by breaking down complex molecules, while anabolic pathways consume energy to build complex molecules.

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 it cannot be created or destroyed.

Question 3

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

Accepted Answer

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

Question 4

A reaction has $$\Delta H = -10 kJ/$$mol and $$\Delta S = +0.05 kJ/($$mol\cdot K)$$ at T = 300 K. $$What is $$\Delta G$$ and is the reaction spontaneous?

Accepted Answer

$$\Delta G = -10 - (300 	imes 0.05) = -25 kJ/$$mol; spontaneous

Question 5

Which of the following is an example of an exergonic reaction?

Accepted Answer

Hydrolysis of ATP to ADP and inorganic phosphate

Question 6

Why must energy from food be released gradually in living organisms?

Accepted Answer

To prevent the loss of all energy as heat and allow controlled use for cellular work

Question 7

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

Accepted Answer

ATP can be easily transported and its hydrolysis releases energy to drive endergonic reactions.

Question 8

Which of the following statements about enzymes is FALSE?

Accepted Answer

Enzymes are consumed during the reaction and cannot be reused.

Question 9

A competitive inhibitor affects an enzyme-catalyzed reaction by:

Accepted Answer

Competing with the substrate for the active site, slowing the reaction rate.

Question 10

Which of the following is a correct description of feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway inhibits an enzyme involved earlier in the pathway.

Question 11

Which of the following best describes the role of NADH and FADH$$_2 in $$cellular respiration?

Accepted Answer

They are reduced coenzymes that carry electrons to the electron transport chain for ATP production.

Question 12

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

Accepted Answer

Increasing the temperature of the cell

Question 13

Which of the following is true about the effect of noncompetitive inhibitors on enzyme activity?

Accepted Answer

They bind to a different site, reducing the maximal rate of the reaction.

Question 14

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

Accepted Answer

Synthesis of proteins from amino acids

Question 15

Which of the following best explains why heat is released during metabolic reactions?

Accepted Answer

Some energy is always lost as heat due to the second law of thermodynamics.

Question 16

Which of the following is a coenzyme required for enzyme function?

Accepted Answer

NADH

Question 17

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

Accepted Answer

The enzyme's active site undergoes a slight change in shape to optimize substrate binding and catalysis.

Question 18

Which of the following reactions is endergonic?

Accepted Answer

ADP phosphorylation: $$\mathrm{ADP} + \mathrm{P_i} + \mathrm{H}^+ \rightarrow \mathrm{ATP} + \mathrm{H}_2\mathrm{O}$$

Question 19

Which of the following is a real-life example of energy coupling in cells?

Accepted Answer

ATP hydrolysis drives the active transport of sodium and potassium ions across the cell membrane.

Question 20

Which of the following best describes the role of allosteric inhibitors in enzyme regulation?

Accepted Answer

They bind to a site other than the active site and reduce enzyme activity.

Metabolism and Enzyme Function in Biological Systems

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