$$\Delta G = -20 - (298 \times -0.05) = -20 + 14.9 = -5.1 kJ/$$mol

Question 1

Which of the following statements best describes the main focus of biochemistry?

Accepted Answer

It studies the atomic structure of biological molecules to explain life processes.

Question 2

Which functional group is most likely to act as a nucleophile in a biochemical reaction?

Accepted Answer

Carboxylate ($$\mathrm{RCOO^-})$$

Question 3

Which of the following best explains why all living cells share common metabolic features?

Accepted Answer

They evolved from a common ancestor and use the same types of biomolecules.

Question 4

Which equation correctly relates Gibbs free energy change to enthalpy and entropy?

Accepted Answer

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

Question 5

A reaction has $$\Delta H = -20 kJ/$$mol and $$\Delta S = -0.05 kJ/($$mol·K)$$. At T = 298$ K, what is $$\Delta G$?

Accepted Answer

$$\Delta G = -20 - (298 	imes -0.05) = -20 + 14.9 = -5.1 kJ/$$mol

Question 6

Which of the following is NOT a type of biochemical reaction listed in the lecture?

Accepted Answer

Hydrolysis

Question 7

What is the main difference between catabolism and anabolism?

Accepted Answer

Catabolism degrades molecules to release energy, while anabolism assembles molecules and requires energy.

Question 8

Which of the following best describes the role of entropy ($$S) in $$the second law of thermodynamics?

Accepted Answer

Entropy measures the disorder of a system and tends to increase over time.

Question 9

Given the equilibrium constant $$K_{eq} = 19 at$$ $$25^\	ext{o}C$$, calculate $$\Delta G$$ using $$R = 8.315 J/($$mol·K).

Accepted Answer

$$\Delta G = -RT \ln(K_{eq}) = -(8.315)(298)\ln(19) = -7.3 kJ/$$mol

Question 10

Which of the following statements about saturated hydrocarbons is correct?

Accepted Answer

They contain only C–C and C–H single bonds and are highly non-polar.

Question 11

Which of the following functional groups is most likely to act as an electrophile?

Accepted Answer

Aldehyde ($$\mathrm{RCHO})$$

Question 12

Why is $$\Delta H$$ alone not a good predictor of reaction spontaneity?

Accepted Answer

Because entropy ($$\Delta S) $$also affects spontaneity, as shown in $$\Delta G = \Delta H - T\Delta S.$$

Question 13

Which of the following best explains how living cells can decrease their internal entropy while obeying the laws of thermodynamics?

Accepted Answer

They increase the entropy of their surroundings by removing free energy from nutrients or sunlight.

Question 14

Which of the following is a correct statement about the equilibrium constant ($$K_{eq}) $$and free energy change ($$\Delta G$$)?

Accepted Answer

If $$K_{eq} \u003e 1$$, $$\Delta G is $$negative and the reaction is spontaneous.

Question 15

Which of the following is an example of a condensation reaction in biochemistry?

Accepted Answer

Formation of a peptide bond between two amino acids with the release of water.

Question 16

Which of the following best describes the relationship between nucleophiles and electrophiles in biochemical reactions?

Accepted Answer

Nucleophiles donate electrons to electrophiles to form new chemical bonds.

Question 17

Which of the following is a correct interpretation of the first law of thermodynamics in biological systems?

Accepted Answer

The total energy of the universe is constant; energy can change forms but cannot be created or destroyed.

Question 18

Which of the following best describes the main difference between animal and plant cells as shown in the lecture?

Accepted Answer

Plant cells contain chloroplasts and a cell wall, which are absent in animal cells.

Introduction to Biochemistry: Cells, Chemical Bonds, Functional Groups, and Thermodynamics

Study Guide - Practice Questions