Question 1

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

Accepted Answer

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

Question 2

A bear eats a fish and then runs, releasing heat and producing $$\mathrm{CO_2$}$$ and $$\mathrm{H_2O}. $$Which law of thermodynamics is best illustrated by the conversion of chemical energy in food to kinetic energy and heat?

Accepted Answer

The first law of thermodynamics, because energy is transferred and transformed but not created or destroyed.

Question 3

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

Accepted Answer

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

Question 4

A cell uses ATP to transport ions against their concentration gradient. Which best describes how ATP powers this process?

Accepted Answer

ATP hydrolysis releases energy, which is directly used to change the shape of the transport protein.

Question 5

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

Accepted Answer

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

Question 6

Why is an organism considered an open system?

Accepted Answer

It exchanges both energy and matter with its surroundings.

Question 7

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

Accepted Answer

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

Question 8

A reaction has a $$\Delta G of$$ $$-5$$ kcal/mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 9

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

Accepted Answer

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

Question 10

A scientist increases the substrate concentration in an enzyme-catalyzed reaction, but the reaction rate no longer increases. What is the most likely explanation?

Accepted Answer

The enzyme is saturated; all active sites are occupied.

Question 11

Which of the following best describes feedback inhibition in a metabolic pathway?

Accepted Answer

The end product of the pathway inhibits an enzyme that acts early in the pathway.

Question 12

Which of the following statements about ATP is correct?

Accepted Answer

ATP stores energy in the bonds between its phosphate groups, which is released during hydrolysis.

Question 13

Which of the following is an example of an allosteric regulator?

Accepted Answer

A molecule that binds to a site other than the active site and changes the enzyme's activity.

Question 14

Which of the following best explains why an investment of activation energy is necessary to initiate a spontaneous reaction?

Accepted Answer

Activation energy is needed to break the bonds of the reactants and reach the transition state.

Question 15

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

Accepted Answer

Binding to the active site and blocking substrate entry.

Question 16

Which of the following scenarios best illustrates the concept of cooperativity in enzyme function?

Accepted Answer

The binding of one oxygen molecule to hemoglobin increases the affinity for additional oxygen molecules.

Question 17

Which of the following is a correct statement about the effect of temperature on enzyme activity?

Accepted Answer

Enzyme activity increases with temperature up to an optimal point, then decreases as the enzyme denatures.

Question 18

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

Accepted Answer

ATP is continuously regenerated from ADP and inorganic phosphate using energy from catabolic reactions.

Question 19

Which of the following is true about noncompetitive enzyme inhibitors?

Accepted Answer

They bind to a site other than the active site, causing a conformational change that reduces enzyme activity.

Chapter 8: An Introduction to Metabolism – Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard