UTSA BIO 1404 Biosciences I Exam 1 - Questions with Correct
Answers (Verified Update)
53 questions
1. Which type of bond forms between the oxygen of one water molecule and a hydrogen of
another?
A. Nonpolar covalent bond
B. Ionic bond
C. Peptide bond
D. Hydrogen bond
Correct Answer: D. Hydrogen bond
Rationale: Water is polar; the partial negative oxygen attracts the partial positive hydrogen of a
neighboring molecule, forming a hydrogen bond.
2. Water's high specific heat is mainly due to:
A. Its nonpolar covalent bonds
B. Hydrogen bonds that absorb heat as they break
C. Its low density as a liquid
D. Ionic bonds between molecules
Correct Answer: B. Hydrogen bonds that absorb heat as they break
Rationale: Energy must first break hydrogen bonds before molecules move faster, so water resists
temperature change.
3. A solution with a pH of 3 compared to a solution with a pH of 5 has:
A. 100 times more H+ ions
B. 2 times more H+ ions
C. 100 times fewer H+ ions
D. 20 times more H+ ions
Correct Answer: A. 100 times more H+ ions
Rationale: The pH scale is logarithmic; each unit is a 10-fold change, so 2 units = 10 x 10 = 100-fold.
4. A buffer helps maintain pH by:
A. Converting acids into water only
B. Accepting or donating H+ ions as needed
C. Adding OH- ions continuously
D. Preventing any ions from dissolving
Correct Answer: B. Accepting or donating H+ ions as needed
Rationale: Buffers (e.g., the bicarbonate system in blood) take up excess H+ or release H+ to resist pH
change.
5. Carbon is the backbone of biological molecules mainly because it:
A. Can form four covalent bonds
B. Is the most abundant element on Earth
C. Forms ionic bonds easily
D. Has no valence electrons
Correct Answer: A. Can form four covalent bonds
Rationale: Four valence electrons allow carbon to form chains, rings and branches with many partners.
, 6. Isotopes of the same element differ in their number of:
A. Protons
B. Electrons
C. Chemical bonds
D. Neutrons
Correct Answer: D. Neutrons
Rationale: Isotopes have the same number of protons (atomic number) but different numbers of
neutrons, giving different masses.
7. Monomers are joined into polymers by which reaction?
A. Hydrolysis
B. Oxidation
C. Denaturation
D. Dehydration synthesis (condensation)
Correct Answer: D. Dehydration synthesis (condensation)
Rationale: Dehydration synthesis removes a water molecule to form each new bond; hydrolysis adds
water to break bonds.
8. Which macromolecule is made of amino acids linked by peptide bonds?
A. Proteins
B. Nucleic acids
C. Carbohydrates
D. Lipids
Correct Answer: A. Proteins
Rationale: Polypeptides are chains of amino acids joined by peptide bonds and fold into functional
proteins.
9. The specific sequence of amino acids in a protein is its:
A. Secondary structure
B. Tertiary structure
C. Quaternary structure
D. Primary structure
Correct Answer: D. Primary structure
Rationale: Primary structure is the linear sequence; it determines how the protein folds into higher levels.
10. Alpha helices and beta pleated sheets are stabilized by hydrogen bonds between backbone
atoms. These are examples of:
A. Primary structure
B. Tertiary structure
C. Quaternary structure
D. Secondary structure
Correct Answer: D. Secondary structure
Rationale: Secondary structure arises from hydrogen bonding along the polypeptide backbone.
11. Hemoglobin consists of four polypeptide subunits. This level of organization is:
A. Tertiary structure
B. Secondary structure
C. Quaternary structure
D. Primary structure
Correct Answer: C. Quaternary structure
Rationale: Quaternary structure describes how multiple polypeptide chains assemble.
Answers (Verified Update)
53 questions
1. Which type of bond forms between the oxygen of one water molecule and a hydrogen of
another?
A. Nonpolar covalent bond
B. Ionic bond
C. Peptide bond
D. Hydrogen bond
Correct Answer: D. Hydrogen bond
Rationale: Water is polar; the partial negative oxygen attracts the partial positive hydrogen of a
neighboring molecule, forming a hydrogen bond.
2. Water's high specific heat is mainly due to:
A. Its nonpolar covalent bonds
B. Hydrogen bonds that absorb heat as they break
C. Its low density as a liquid
D. Ionic bonds between molecules
Correct Answer: B. Hydrogen bonds that absorb heat as they break
Rationale: Energy must first break hydrogen bonds before molecules move faster, so water resists
temperature change.
3. A solution with a pH of 3 compared to a solution with a pH of 5 has:
A. 100 times more H+ ions
B. 2 times more H+ ions
C. 100 times fewer H+ ions
D. 20 times more H+ ions
Correct Answer: A. 100 times more H+ ions
Rationale: The pH scale is logarithmic; each unit is a 10-fold change, so 2 units = 10 x 10 = 100-fold.
4. A buffer helps maintain pH by:
A. Converting acids into water only
B. Accepting or donating H+ ions as needed
C. Adding OH- ions continuously
D. Preventing any ions from dissolving
Correct Answer: B. Accepting or donating H+ ions as needed
Rationale: Buffers (e.g., the bicarbonate system in blood) take up excess H+ or release H+ to resist pH
change.
5. Carbon is the backbone of biological molecules mainly because it:
A. Can form four covalent bonds
B. Is the most abundant element on Earth
C. Forms ionic bonds easily
D. Has no valence electrons
Correct Answer: A. Can form four covalent bonds
Rationale: Four valence electrons allow carbon to form chains, rings and branches with many partners.
, 6. Isotopes of the same element differ in their number of:
A. Protons
B. Electrons
C. Chemical bonds
D. Neutrons
Correct Answer: D. Neutrons
Rationale: Isotopes have the same number of protons (atomic number) but different numbers of
neutrons, giving different masses.
7. Monomers are joined into polymers by which reaction?
A. Hydrolysis
B. Oxidation
C. Denaturation
D. Dehydration synthesis (condensation)
Correct Answer: D. Dehydration synthesis (condensation)
Rationale: Dehydration synthesis removes a water molecule to form each new bond; hydrolysis adds
water to break bonds.
8. Which macromolecule is made of amino acids linked by peptide bonds?
A. Proteins
B. Nucleic acids
C. Carbohydrates
D. Lipids
Correct Answer: A. Proteins
Rationale: Polypeptides are chains of amino acids joined by peptide bonds and fold into functional
proteins.
9. The specific sequence of amino acids in a protein is its:
A. Secondary structure
B. Tertiary structure
C. Quaternary structure
D. Primary structure
Correct Answer: D. Primary structure
Rationale: Primary structure is the linear sequence; it determines how the protein folds into higher levels.
10. Alpha helices and beta pleated sheets are stabilized by hydrogen bonds between backbone
atoms. These are examples of:
A. Primary structure
B. Tertiary structure
C. Quaternary structure
D. Secondary structure
Correct Answer: D. Secondary structure
Rationale: Secondary structure arises from hydrogen bonding along the polypeptide backbone.
11. Hemoglobin consists of four polypeptide subunits. This level of organization is:
A. Tertiary structure
B. Secondary structure
C. Quaternary structure
D. Primary structure
Correct Answer: C. Quaternary structure
Rationale: Quaternary structure describes how multiple polypeptide chains assemble.
