Q: Which of the following best describes the primary structure of a nucleic acid?

The sequence of nucleotides linked by phosphodiester bonds.

Q: Which functional group is present in all amino acids and is essential for peptide bond formation?

Both carboxyl ($\mathrm{-COOH}$) and amino ($\mathrm{-NH_2}$) groups

Q: Which of the following is a correct statement about entropy ($S$) in a biochemical reaction?

If $\Delta S > 0$, the system becomes more random.

Question 1

Which of the following statements best describes the directionality of a protein polymer?

Accepted Answer

Proteins are synthesized from the amino terminus to the carboxyl terminus, giving them directionality.

Question 2

Which functional group is characteristic of alcohols and is commonly found in carbohydrates?

Accepted Answer

Hydroxyl group ($\mathrm{-OH}$)

Question 3

Given the equation $\Delta G = \Delta H - T\Delta S$, which scenario will always result in a spontaneous reaction?

Accepted Answer

$\Delta H < 0$ and $\Delta S > 0$

Question 4

Which of the following best explains why living cells are considered open systems in thermodynamics?

Accepted Answer

They exchange both energy and matter with their surroundings.

Question 5

Which element is much more abundant in organisms than in the universe, relative to carbon?

Accepted Answer

Nitrogen

Question 6

A reaction has $\Delta H = -50\ \mathrm{kJ\ mol^{-1}}$ and $\Delta S = -0.1\ \mathrm{kJ\ mol^{-1}\ K^{-1}}$ at $T = 298\ \mathrm{K}$. Calculate $\Delta G$ and determine if the reaction is spontaneous.

Accepted Answer

$\Delta G = -20.2\ \mathrm{kJ\ mol^{-1}}$, spontaneous

Question 7

Which of the following is NOT a polymer made from the listed monomer?

Accepted Answer

Lipids from nucleotides

Question 8

Which functional group is responsible for the acidic properties of amino acids and is found at the carboxyl terminus?

Accepted Answer

Carboxyl group ($\mathrm{-COOH}$)

Question 9

Which statement about the spontaneity of a reaction is correct?

Accepted Answer

A spontaneous reaction has $\Delta G < 0$ but may not be fast.

Question 10

Which of the following best describes the primary structure of a nucleic acid?

Accepted Answer

The sequence of nucleotides linked by phosphodiester bonds.

Question 11

Which functional group is present in all amino acids and is essential for peptide bond formation?

Accepted Answer

Both carboxyl ($\mathrm{-COOH}$) and amino ($\mathrm{-NH_2}$) groups

Question 12

Which of the following is a correct statement about entropy ($S$) in a biochemical reaction?

Accepted Answer

If $\Delta S > 0$, the system becomes more random.

Question 13

Which of the following is true about the ATP hydrolysis reaction: $\mathrm{ATP} + \mathrm{H_2O} \rightarrow \mathrm{ADP} + \mathrm{P_i}$?

Accepted Answer

It is exergonic with $\Delta G < 0$.

Question 14

Which of the following best describes the difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have membrane-bound organelles, prokaryotic cells do not.

Question 15

Which of the following is a correct application of the concept of free energy change ($\Delta G$) in metabolism?

Accepted Answer

A reaction with $\Delta G < 0$ can be coupled to drive non-spontaneous reactions.

Question 16

Which functional group is found in nucleic acids and is essential for their backbone structure?

Accepted Answer

Phosphate group ($\mathrm{-PO_4^{3-}}$)

Question 17

Which of the following statements about the evolution from the RNA-world to the protein-world is most accurate?

Accepted Answer

RNA molecules acted as both genetic material and catalysts before proteins evolved.

Question 18

Which of the following is a correct statement about the abundance of elements in organisms compared to the universe?

Accepted Answer

Nitrogen is much more abundant in organisms than in the universe.

Question 19

Which of the following is a correct multi-step analysis of a biochemical process: If a reaction has $\Delta H = 40\ \mathrm{kJ\ mol^{-1}}$ and $\Delta S = 0.2\ \mathrm{kJ\ mol^{-1}\ K^{-1}}$ at $T = 300\ \mathrm{K}$, what is $\Delta G$ and is the reaction spontaneous?

Accepted Answer

$\Delta G = -20\ \mathrm{kJ\ mol^{-1}}$, spontaneous

Introduction to Biochemistry: Macromolecules, Functional Groups, and Thermodynamics Ch 1

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