$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$$

Question 1

Which of the following best describes the role of enzymes in metabolic pathways?

Accepted Answer

Enzymes catalyze each step of a metabolic pathway by lowering the activation energy, allowing reactions to proceed faster without being consumed.

Question 2

A firefly produces light through bioluminescence. Which type of energy transformation is primarily involved in this process?

Accepted Answer

Conversion of chemical energy to light energy

Question 3

Which statement correctly applies the first law of thermodynamics to cellular respiration?

Accepted Answer

Energy is transformed from chemical energy in glucose to other forms, but the total energy remains constant.

Question 4

Which of the following equations correctly represents the hydrolysis of ATP?

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy}$$

Question 5

A cell builds a protein from amino acids. Which type of metabolic pathway and reaction is this?

Accepted Answer

Anabolic pathway; endergonic reaction

Question 6

Which of the following best explains why metabolic pathways in cells never reach equilibrium?

Accepted Answer

Cells are open systems with a constant flow of materials in and out, so products of one reaction become reactants for the next.

Question 7

Which of the following is a correct statement about the second law of thermodynamics?

Accepted Answer

Every energy transfer increases the entropy (disorder) of the universe.

Question 8

A reaction has a negative $$\Delta G. $$What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and can occur spontaneously.

Question 9

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

Accepted Answer

Covalently bonding to the substrate permanently

Question 10

Which scenario best illustrates feedback inhibition in a metabolic pathway?

Accepted Answer

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

Question 11

Which of the following is true about competitive enzyme inhibitors?

Accepted Answer

They compete with the substrate for binding at the enzyme's active site.

Question 12

Which of the following best describes the coupling of exergonic and endergonic reactions in cells?

Accepted Answer

Cells use the energy released from exergonic reactions to drive endergonic reactions, often via ATP hydrolysis.

Question 13

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

Accepted Answer

The concentration gradient of ions across a membrane

Question 14

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

Accepted Answer

$$\Delta G = G_{final} - G_{initial}$$

Question 15

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

Accepted Answer

Adding more enzyme to the reaction

Question 16

Which statement best explains why high temperatures can denature enzymes?

Accepted Answer

High temperatures disrupt the weak interactions that maintain the enzyme's three-dimensional structure.

Question 17

Which of the following is a correct example of an exergonic reaction in a cell?

Accepted Answer

Hydrolysis of ATP to ADP and $$P_i$$

Question 18

Which of the following statements about allosteric regulation of enzymes is correct?

Accepted Answer

Allosteric regulation involves binding of a molecule at a site other than the active site, which can inhibit or stimulate enzyme activity.

Question 19

A cell is performing mechanical work, such as moving a vesicle along cytoskeletal fibers. Which process provides the energy for this work?

Accepted Answer

Hydrolysis of ATP, which changes the shape of motor proteins and allows movement.

Chapter 6: An Introduction to Metabolism – Study Notes

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