Question 1

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

Accepted Answer

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

Question 2

A bear eats a fish and uses the energy to run. According to the laws of thermodynamics, what happens to the energy from the fish?

Accepted Answer

Some energy is lost as heat, increasing the entropy of the universe, while the rest is used for work.

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

Exergonic reactions have a negative $$\Delta G$$ and occur spontaneously.

Question 5

ATP is classified as which type of macromolecule?

Accepted Answer

Nucleic acid

Question 6

What is the primary mechanism by which ATP powers cellular work?

Accepted Answer

By hydrolysis of ATP, releasing energy and transferring a phosphate group to another molecule (phosphorylation).

Question 7

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

Accepted Answer

Enzymes have active sites whose shapes are complementary to the shapes of their substrates.

Question 8

Why is an investment of activation energy necessary to initiate a spontaneous reaction?

Accepted Answer

Activation energy is needed to destabilize reactant bonds and reach the transition state.

Question 9

How do enzymes lower the activation energy of a reaction?

Accepted Answer

By stabilizing the transition state and orienting substrates correctly.

Question 10

A competitive inhibitor affects enzyme activity by:

Accepted Answer

Binding to the enzyme's active site and blocking substrate access.

Question 11

Which of the following is true about feedback inhibition in metabolic pathways?

Accepted Answer

The end product of a pathway inhibits an enzyme early in the pathway, preventing overproduction.

Question 12

Which environmental factor is most likely to cause an enzyme to denature?

Accepted Answer

A temperature significantly above the enzyme's optimal temperature.

Question 13

Which statement best describes the induced-fit model of enzyme function?

Accepted Answer

The enzyme changes shape slightly to fit the substrate more tightly upon binding.

Question 14

If an enzyme is saturated with substrate, how can the rate of reaction be increased?

Accepted Answer

By adding more enzyme.

Question 15

Which of the following is an example of an inorganic cofactor?

Accepted Answer

Zinc ion ($$	ext{Zn}^{2+})$$

Question 16

Which process is spontaneous according to the second law of thermodynamics?

Accepted Answer

Diffusion of molecules from high to low concentration.

Question 17

Which of the following best explains why an organism is considered an open system?

Accepted Answer

It exchanges both energy and matter with its surroundings.

Question 18

Which of the following statements about the ATP cycle is correct?

Accepted Answer

ATP is regenerated by the addition of a phosphate group to ADP, 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 the enzyme to change shape and reducing its activity.

Question 20

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

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Chapter 8: An Introduction to Metabolism – Study Notes

Guida di studio - Domande di pratica