CHEM 210 Biochemistry | Portage Learning | Modules 1–8 +
Final Exam | 2026/2027
Questions & Answers | Practice Study Guide | 30 Questions Per Module + 40 Final Exam
Questions
Read each question carefully. Correct answers are marked in bold cyan. Detailed rationales follow each question.
1
, Module 1: Biomolecules & Chemical Foundations
Score: _________ / 30
Section I: Multiple-Choice Questions
1. Which of the following is the strongest type of chemical bond in biological systems?
A) Hydrogen bond
B) Ionic bond
C) Covalent bond
D) Van der Waals interaction
Rationale: Covalent bonds involve the sharing of electron pairs between atoms and are the strongest bonds found in
biological molecules. Hydrogen bonds and van der Waals interactions are much weaker noncovalent interactions,
while ionic bonds, though strong, are often disrupted in aqueous environments.
2. What is the electronegativity difference threshold above which a bond is considered ionic?
A) 1.0
B) 1.7
C) 2.5
D) 0.5
Rationale: An electronegativity difference greater than 1.7 between two atoms generally results in an ionic bond,
where electrons are transferred rather than shared. Differences below 1.7 typically produce covalent bonds.
3. Which functional group is characterized by the formula -COOH?
A) Amino group
B) Carboxyl group
C) Hydroxyl group
D) Carbonyl group
Rationale: The carboxyl group (-COOH) consists of a carbonyl (C=O) bonded to a hydroxyl (-OH). It is a key
functional group in amino acids and fatty acids, and acts as a weak acid by donating a proton.
4. Which of the following is an example of a sulfhydryl functional group?
A) -OH
B) -NH2
C) -SH
D) -COOH
2
,Rationale: The sulfhydryl group (-SH) contains sulfur bonded to hydrogen. It is found in the amino acid cysteine and
is critical for forming disulfide bonds that stabilize protein tertiary structure.
5. The phosphate functional group (-PO4) is most commonly found in which class of biomolecules?
A) Proteins
B) Carbohydrates
C) Nucleic acids
D) Lipids
Rationale: Phosphate groups are integral components of nucleic acids (DNA and RNA), forming the sugar-phosphate
backbone. They are also found in ATP and phospholipids, but nucleic acids are the most directly associated.
6. Water is considered a polar molecule because:
A) It has a linear geometry
B) It has a bent geometry with unequal charge distribution
C) It contains hydrogen bonds
D) It has a high molecular weight
Rationale: Water's bent geometry (bond angle ~104.5 degrees) creates an uneven distribution of electron density,
resulting in a partial negative charge on oxygen and partial positive charges on the hydrogens. This polarity enables
hydrogen bonding.
7. Which of the following is NOT a type of isomer?
A) Structural isomer
B) Stereoisomer
C) Functional isomer
D) Radioactive isomer
Rationale: Radioactive isomers are not a recognized category of chemical isomers. Structural isomers differ in
connectivity, stereoisomers differ in spatial arrangement, and functional isomers have the same molecular formula but
different functional groups.
8. Which element is the most electronegative among the following?
A) Carbon (2.5)
B) Nitrogen (3.0)
C) Oxygen (3.5)
D) Sulfur (2.5)
3
, Rationale: Oxygen has an electronegativity of 3.5 on the Pauling scale, making it the most electronegative element
listed. High electronegativity makes oxygen a strong participant in polar covalent bonds and hydrogen bonds.
9. A molecule with the formula C6H12O6 could be which of the following?
A) Glucose
B) Fructose
C) Both A and B
D) Neither A nor B
Rationale: Both glucose and fructose have the molecular formula C6H12O6, making them structural isomers.
Glucose is an aldohexose (aldehyde group), while fructose is a ketohexose (ketone group).
10. The hydroxyl group (-OH) is characteristic of which class of organic compounds?
A) Amines
B) Alcohols
C) Carboxylic acids
D) Ketones
Rationale: The hydroxyl group (-OH) defines alcohols. In biochemistry, this group is found in sugars
(carbohydrates), cholesterol, and many other biomolecules.
11. In a molecule of methane (CH4), the carbon atom exhibits which type of hybridization?
A) sp
B) sp2
C) sp3
D) sp3d
Rationale: Carbon in methane undergoes sp3 hybridization, forming four equivalent sigma bonds arranged in a
tetrahedral geometry with bond angles of approximately 109.5 degrees.
12. Which bond is primarily responsible for the secondary structure of proteins?
A) Peptide bonds
B) Hydrogen bonds
C) Disulfide bonds
D) Ionic bonds
Rationale: Hydrogen bonds between backbone amide hydrogen and carbonyl oxygen atoms stabilize secondary
structures such as alpha-helices and beta-sheets in proteins.
13. What is the molecular geometry of a carbon atom with a double bond (e.g., in C=O)?
4
Final Exam | 2026/2027
Questions & Answers | Practice Study Guide | 30 Questions Per Module + 40 Final Exam
Questions
Read each question carefully. Correct answers are marked in bold cyan. Detailed rationales follow each question.
1
, Module 1: Biomolecules & Chemical Foundations
Score: _________ / 30
Section I: Multiple-Choice Questions
1. Which of the following is the strongest type of chemical bond in biological systems?
A) Hydrogen bond
B) Ionic bond
C) Covalent bond
D) Van der Waals interaction
Rationale: Covalent bonds involve the sharing of electron pairs between atoms and are the strongest bonds found in
biological molecules. Hydrogen bonds and van der Waals interactions are much weaker noncovalent interactions,
while ionic bonds, though strong, are often disrupted in aqueous environments.
2. What is the electronegativity difference threshold above which a bond is considered ionic?
A) 1.0
B) 1.7
C) 2.5
D) 0.5
Rationale: An electronegativity difference greater than 1.7 between two atoms generally results in an ionic bond,
where electrons are transferred rather than shared. Differences below 1.7 typically produce covalent bonds.
3. Which functional group is characterized by the formula -COOH?
A) Amino group
B) Carboxyl group
C) Hydroxyl group
D) Carbonyl group
Rationale: The carboxyl group (-COOH) consists of a carbonyl (C=O) bonded to a hydroxyl (-OH). It is a key
functional group in amino acids and fatty acids, and acts as a weak acid by donating a proton.
4. Which of the following is an example of a sulfhydryl functional group?
A) -OH
B) -NH2
C) -SH
D) -COOH
2
,Rationale: The sulfhydryl group (-SH) contains sulfur bonded to hydrogen. It is found in the amino acid cysteine and
is critical for forming disulfide bonds that stabilize protein tertiary structure.
5. The phosphate functional group (-PO4) is most commonly found in which class of biomolecules?
A) Proteins
B) Carbohydrates
C) Nucleic acids
D) Lipids
Rationale: Phosphate groups are integral components of nucleic acids (DNA and RNA), forming the sugar-phosphate
backbone. They are also found in ATP and phospholipids, but nucleic acids are the most directly associated.
6. Water is considered a polar molecule because:
A) It has a linear geometry
B) It has a bent geometry with unequal charge distribution
C) It contains hydrogen bonds
D) It has a high molecular weight
Rationale: Water's bent geometry (bond angle ~104.5 degrees) creates an uneven distribution of electron density,
resulting in a partial negative charge on oxygen and partial positive charges on the hydrogens. This polarity enables
hydrogen bonding.
7. Which of the following is NOT a type of isomer?
A) Structural isomer
B) Stereoisomer
C) Functional isomer
D) Radioactive isomer
Rationale: Radioactive isomers are not a recognized category of chemical isomers. Structural isomers differ in
connectivity, stereoisomers differ in spatial arrangement, and functional isomers have the same molecular formula but
different functional groups.
8. Which element is the most electronegative among the following?
A) Carbon (2.5)
B) Nitrogen (3.0)
C) Oxygen (3.5)
D) Sulfur (2.5)
3
, Rationale: Oxygen has an electronegativity of 3.5 on the Pauling scale, making it the most electronegative element
listed. High electronegativity makes oxygen a strong participant in polar covalent bonds and hydrogen bonds.
9. A molecule with the formula C6H12O6 could be which of the following?
A) Glucose
B) Fructose
C) Both A and B
D) Neither A nor B
Rationale: Both glucose and fructose have the molecular formula C6H12O6, making them structural isomers.
Glucose is an aldohexose (aldehyde group), while fructose is a ketohexose (ketone group).
10. The hydroxyl group (-OH) is characteristic of which class of organic compounds?
A) Amines
B) Alcohols
C) Carboxylic acids
D) Ketones
Rationale: The hydroxyl group (-OH) defines alcohols. In biochemistry, this group is found in sugars
(carbohydrates), cholesterol, and many other biomolecules.
11. In a molecule of methane (CH4), the carbon atom exhibits which type of hybridization?
A) sp
B) sp2
C) sp3
D) sp3d
Rationale: Carbon in methane undergoes sp3 hybridization, forming four equivalent sigma bonds arranged in a
tetrahedral geometry with bond angles of approximately 109.5 degrees.
12. Which bond is primarily responsible for the secondary structure of proteins?
A) Peptide bonds
B) Hydrogen bonds
C) Disulfide bonds
D) Ionic bonds
Rationale: Hydrogen bonds between backbone amide hydrogen and carbonyl oxygen atoms stabilize secondary
structures such as alpha-helices and beta-sheets in proteins.
13. What is the molecular geometry of a carbon atom with a double bond (e.g., in C=O)?
4
