UTSA BIO 1404 Biosciences I Exam 2 - Questions with Correct
Answers (Verified Update)
54 questions
1. An atom has 6 protons, 6 neutrons and 6 electrons. Its atomic mass is approximately:
A. 12
B. 6
C. 18
D. 24
Correct Answer: A. 12
Rationale: Mass number = protons + neutrons = 6 + 6 = 12 (this is carbon-12).
2. Ice floats on liquid water because:
A. Ice contains more molecules per volume
B. Ice has ionic bonds
C. Ice is heavier than water
D. Hydrogen bonds hold ice molecules in a less dense, open lattice
Correct Answer: D. Hydrogen bonds hold ice molecules in a less dense, open lattice
Rationale: Stable hydrogen bonds space molecules farther apart in ice, insulating lakes so life survives
beneath.
3. Which property of water allows it to move up the xylem of tall plants?
A. Low specific heat
B. Nonpolarity
C. Cohesion and adhesion
D. Ionic bonding
Correct Answer: C. Cohesion and adhesion
Rationale: Cohesion (water-water hydrogen bonds) and adhesion (water-wall attraction) support capillary
action and transpiration pull.
4. A molecule that dissolves easily in water is described as:
A. Hydrophobic
B. Nonpolar
C. Hydrophilic
D. Amphipathic only
Correct Answer: C. Hydrophilic
Rationale: Polar and charged molecules interact with water and are hydrophilic.
5. A bond in which electrons are shared unequally between atoms is a:
A. Nonpolar covalent bond
B. Ionic bond
C. Hydrogen bond
D. Polar covalent bond
Correct Answer: D. Polar covalent bond
Rationale: Unequal sharing arises from differences in electronegativity, as in the O-H bonds of water.
, 6. Adding a strong acid to pure water will:
A. Decrease H+ concentration and raise pH
B. Increase H+ concentration and lower the pH
C. Have no effect on pH
D. Increase OH- concentration
Correct Answer: B. Increase H+ concentration and lower the pH
Rationale: Acids release H+; more H+ means lower pH.
7. Which functional group gives amino acids their acidic property?
A. Amino group (-NH2)
B. Carboxyl group (-COOH)
C. Hydroxyl group (-OH)
D. Methyl group (-CH3)
Correct Answer: B. Carboxyl group (-COOH)
Rationale: The carboxyl group can release H+; the amino group acts as a base.
8. What determines the unique chemical properties of each of the 20 amino acids?
A. Its amino group
B. Its carboxyl group
C. Its central carbon only
D. Its R group (side chain)
Correct Answer: D. Its R group (side chain)
Rationale: All amino acids share the same backbone; R groups vary in size, charge and polarity.
9. Disulfide bridges between cysteine residues help stabilize a protein's:
A. Tertiary structure
B. Primary structure
C. Secondary structure only
D. Peptide bonds
Correct Answer: A. Tertiary structure
Rationale: Covalent S-S bonds between R groups help fix the overall 3D shape.
10. Animals store glucose for short-term energy as:
A. Starch
B. Cellulose
C. Glycogen
D. Chitin
Correct Answer: C. Glycogen
Rationale: Glycogen is a highly branched glucose polymer stored in liver and muscle.
11. Which is NOT a lipid?
A. Cholesterol
B. Triglyceride
C. Glucose
D. Phospholipid
Correct Answer: C. Glucose
Rationale: Glucose is a monosaccharide carbohydrate; steroids, fats and phospholipids are lipids.
Answers (Verified Update)
54 questions
1. An atom has 6 protons, 6 neutrons and 6 electrons. Its atomic mass is approximately:
A. 12
B. 6
C. 18
D. 24
Correct Answer: A. 12
Rationale: Mass number = protons + neutrons = 6 + 6 = 12 (this is carbon-12).
2. Ice floats on liquid water because:
A. Ice contains more molecules per volume
B. Ice has ionic bonds
C. Ice is heavier than water
D. Hydrogen bonds hold ice molecules in a less dense, open lattice
Correct Answer: D. Hydrogen bonds hold ice molecules in a less dense, open lattice
Rationale: Stable hydrogen bonds space molecules farther apart in ice, insulating lakes so life survives
beneath.
3. Which property of water allows it to move up the xylem of tall plants?
A. Low specific heat
B. Nonpolarity
C. Cohesion and adhesion
D. Ionic bonding
Correct Answer: C. Cohesion and adhesion
Rationale: Cohesion (water-water hydrogen bonds) and adhesion (water-wall attraction) support capillary
action and transpiration pull.
4. A molecule that dissolves easily in water is described as:
A. Hydrophobic
B. Nonpolar
C. Hydrophilic
D. Amphipathic only
Correct Answer: C. Hydrophilic
Rationale: Polar and charged molecules interact with water and are hydrophilic.
5. A bond in which electrons are shared unequally between atoms is a:
A. Nonpolar covalent bond
B. Ionic bond
C. Hydrogen bond
D. Polar covalent bond
Correct Answer: D. Polar covalent bond
Rationale: Unequal sharing arises from differences in electronegativity, as in the O-H bonds of water.
, 6. Adding a strong acid to pure water will:
A. Decrease H+ concentration and raise pH
B. Increase H+ concentration and lower the pH
C. Have no effect on pH
D. Increase OH- concentration
Correct Answer: B. Increase H+ concentration and lower the pH
Rationale: Acids release H+; more H+ means lower pH.
7. Which functional group gives amino acids their acidic property?
A. Amino group (-NH2)
B. Carboxyl group (-COOH)
C. Hydroxyl group (-OH)
D. Methyl group (-CH3)
Correct Answer: B. Carboxyl group (-COOH)
Rationale: The carboxyl group can release H+; the amino group acts as a base.
8. What determines the unique chemical properties of each of the 20 amino acids?
A. Its amino group
B. Its carboxyl group
C. Its central carbon only
D. Its R group (side chain)
Correct Answer: D. Its R group (side chain)
Rationale: All amino acids share the same backbone; R groups vary in size, charge and polarity.
9. Disulfide bridges between cysteine residues help stabilize a protein's:
A. Tertiary structure
B. Primary structure
C. Secondary structure only
D. Peptide bonds
Correct Answer: A. Tertiary structure
Rationale: Covalent S-S bonds between R groups help fix the overall 3D shape.
10. Animals store glucose for short-term energy as:
A. Starch
B. Cellulose
C. Glycogen
D. Chitin
Correct Answer: C. Glycogen
Rationale: Glycogen is a highly branched glucose polymer stored in liver and muscle.
11. Which is NOT a lipid?
A. Cholesterol
B. Triglyceride
C. Glucose
D. Phospholipid
Correct Answer: C. Glucose
Rationale: Glucose is a monosaccharide carbohydrate; steroids, fats and phospholipids are lipids.
