Q: Which of the following best describes the role of enzymes in biochemical reactions?

Enzymes act as catalysts, lowering the activation energy and increasing reaction rates.

Q: Which of the following is true about the abundance of nitrogen in organisms compared to the universe?

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

Question 1

Which of the following statements best describes the 'directionality' of a nucleic acid polymer?

Accepted Answer

Nucleic acids have a free 5' phosphate group at one end and a free 3' hydroxyl group at the other, indicating directionality from 5' to 3'.

Question 2

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

Accepted Answer

Hydroxyl group $(-OH)$

Question 3

A biochemical 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

$\Delta G = -79.8\ \mathrm{kJ\ mol^{-1}}$, spontaneous

Question 4

Which element is much more abundant in living organisms compared to its abundance in the universe?

Accepted Answer

Phosphorus

Question 5

Which statement correctly describes the difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus, whereas prokaryotic cells lack a nucleus.

Question 6

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

Accepted Answer

Lipids from nucleotides

Question 7

A reaction has $\Delta G > 0$. What does this indicate about the reaction?

Accepted Answer

The reaction is non-spontaneous and requires energy input.

Question 8

Which functional group is responsible for the acidic properties of amino acids?

Accepted Answer

Carboxyl group $(-COOH)$

Question 9

Which of the following best explains why ATP hydrolysis is highly exergonic?

Accepted Answer

ATP hydrolysis forms stronger bonds in the products and increases entropy.

Question 10

Which class of thermodynamic system best describes a living cell?

Accepted Answer

Open system

Question 11

Which of the following statements about entropy ($S$) is correct?

Accepted Answer

A positive $\Delta S$ means the system has become more random.

Question 12

Which of the following is a correct representation of the free energy change equation?

Accepted Answer

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

Question 13

Which functional group is found in all nucleotides and is essential for nucleic acid polymerization?

Accepted Answer

Phosphate group $(-PO_4)$

Question 14

Which of the following statements about spontaneous reactions is true?

Accepted Answer

Spontaneous reactions have $\Delta G < 0$.

Question 15

Which of the following is a chemically distinct terminal group in a polypeptide chain?

Accepted Answer

Amino terminal ($N$-terminus)

Question 16

Which of the following is a correct pairing of monomer and polymer?

Accepted Answer

Nucleotide — Nucleic acid

Question 17

Which functional group is present in all amino acids and is responsible for their basic properties?

Accepted Answer

Amino group $(-NH_2)$

Question 18

Which of the following best describes the role of enzymes in biochemical reactions?

Accepted Answer

Enzymes act as catalysts, lowering the activation energy and increasing reaction rates.

Question 19

Which of the following is true about the abundance of nitrogen in organisms compared to the universe?

Accepted Answer

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

Question 20

A reaction at constant pressure has $\Delta H = +30\ \mathrm{kJ\ mol^{-1}}$ and $\Delta S = +0.15\ \mathrm{kJ\ mol^{-1}\ K^{-1}}$ at $T = 298\ \mathrm{K}$. Is the reaction spontaneous?

Accepted Answer

Yes, because $\Delta G < 0$

Introduction to Biochemistry: Macromolecules, Functional Groups, and Thermodynamics

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