Question 1

Which statement best describes the First Law of Thermodynamics as it applies to biological systems?

Accepted Answer

Energy cannot be created or destroyed, but can be converted from one form to another.

Question 2

A chemical reaction in a cell has $$\Delta G = -15 kJ/$$mol. What does this indicate about the reaction?

Accepted Answer

The reaction is exergonic and will occur spontaneously.

Question 3

Which of the following changes would most likely increase the entropy ($$S) of a $$system?

Accepted Answer

Breaking down a large macromolecule into smaller subunits.

Question 4

In the context of covalent bonds, which bond has the highest potential energy?

Accepted Answer

C—H bond

Question 5

Which equation correctly relates the change in free energy ($$\Delta G) to $$enthalpy ($$\Delta H$$), entropy ($$\Delta S$$), and temperature ($$T$$)?

Accepted Answer

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

Question 6

During the hydrolysis of ATP, which of the following occurs?

Accepted Answer

ATP is converted to ADP and inorganic phosphate, releasing energy.

Question 7

Which process is an example of an anabolic reaction in metabolism?

Accepted Answer

Protein synthesis from amino acids.

Question 8

A cell couples the endergonic synthesis of glutamine ($$\Delta G = +3.4$$ kcal/mol) with ATP hydrolysis ($$\Delta G = -7.3$$ kcal/mol). What is the net $$\Delta G$$ for the coupled reaction?

Accepted Answer

$$-3.9$$ kcal/mol

Question 9

Why does phosphorylation of a substrate by ATP often make the substrate more reactive?

Accepted Answer

It increases the substrate's free energy, making it less stable and more likely to react.

Question 10

Which of the following is true about exergonic reactions in biological systems?

Accepted Answer

They release energy and occur spontaneously.

Question 11

In a cell, which scenario would most likely result in a decrease in enthalpy ($$H) $$and an increase in entropy ($$S$$)?

Accepted Answer

Breakdown of starch into glucose molecules.

Question 12

Which statement best explains why ATP is considered an energy shuttle in metabolism?

Accepted Answer

ATP transfers energy via its phosphate groups to drive endergonic reactions.

Question 13

Which of the following is a correct example of energy transformation in a biological system?

Accepted Answer

Conversion of chemical potential energy in glucose to kinetic energy during cellular respiration.

Question 14

Which of the following statements about the Second Law of Thermodynamics is correct?

Accepted Answer

Energy spontaneously disperses from being localized to becoming spread out unless hindered.

Question 15

Which of the following best describes a catabolic pathway?

Accepted Answer

It breaks down complex molecules into simpler ones and releases energy.

Question 16

What is the role of active carrier molecules such as NADH and FADH$$_2 in $$metabolism?

Accepted Answer

They transfer electrons and energy between metabolic reactions.

Question 17

Which of the following would most likely make a reaction spontaneous at a constant temperature?

Accepted Answer

A decrease in enthalpy ($$\Delta H  0).$$

Question 18

Which of the following is a real-life example of coupling an exergonic and endergonic reaction in cells?

Accepted Answer

Using ATP hydrolysis to drive the synthesis of glutamine from glutamic acid and ammonia.

Question 19

Which of the following statements about the potential energy in chemical bonds is correct?

Accepted Answer

Nonpolar covalent bonds generally have higher potential energy than polar covalent bonds.

Question 20

Which of the following best explains why the combustion of glucose is spontaneous?

Accepted Answer

It results in products with lower enthalpy and higher entropy.

Energy, Metabolism, and Enzymes in Biological Systems

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