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CHEM 210 Biochemistry – Module 1 Exam
1. Biochemistry is best described as the study of:
A. Chemical reactions occurring only in living cells
B. Biological processes explained through chemical principles
C. Organic chemistry limited to proteins and enzymes
D. Cellular physiology independent of chemistry
Correct Answer: B
Rationale: Biochemistry integrates chemistry and biology to explain biological
processes at the molecular level. It is broader than cellular reactions alone and
includes all biomolecules.
2. Which element is most commonly involved in hydrogen bonding within
biological molecules?
A. Carbon
B. Oxygen
C. Phosphorus
D. Sulfur
Correct Answer: B
Rationale: Oxygen is highly electronegative, allowing it to participate readily in
hydrogen bonding, which is critical for water structure, protein folding, and nucleic
acid stability.
,3. The atomic number of an element indicates the:
A. Number of neutrons
B. Atomic mass
C. Number of protons
D. Total electrons and neutrons
Correct Answer: C
Rationale: Atomic number uniquely identifies an element and equals the number
of protons in the nucleus.
4. Which bond is strongest in biological systems?
A. Hydrogen bond
B. Ionic bond
C. Covalent bond
D. Van der Waals interaction
Correct Answer: C
Rationale: Covalent bonds involve the sharing of electrons and are significantly
stronger than noncovalent interactions.
5. A molecule that can donate a proton is classified as a:
A. Base
B. Buffer
C. Acid
D. Salt
Correct Answer: C
Rationale: According to the Brønsted–Lowry definition, acids donate protons (H⁺
ions).
,6. The pH scale measures:
A. Hydroxide ion concentration
B. Hydrogen ion concentration
C. Salt concentration
D. Buffering capacity
Correct Answer: B
Rationale: pH is a logarithmic measure of hydrogen ion concentration, indicating
acidity or alkalinity.
7. A solution with a pH of 5 is how many times more acidic than a solution
with pH 7?
A. 2 times
B. 10 times
C. 100 times
D. 1,000 times
Correct Answer: C
Rationale: Each unit change in pH represents a tenfold difference in hydrogen ion
concentration; a two-unit difference equals 100-fold.
8. Which interaction is primarily responsible for stabilizing protein secondary
structure?
A. Ionic bonds
B. Hydrogen bonds
C. Disulfide bonds
D. Hydrophobic interactions
Correct Answer: B
Rationale: Alpha helices and beta sheets are stabilized mainly by hydrogen bonds
between backbone atoms.
, 9. Which type of bond forms between oppositely charged ions?
A. Covalent
B. Hydrogen
C. Ionic
D. Metallic
Correct Answer: C
Rationale: Ionic bonds result from electrostatic attraction between oppositely
charged ions.
10. Water is an excellent solvent because it:
A. Is nonpolar
B. Forms hydrogen bonds
C. Has a low boiling point
D. Is chemically inert
Correct Answer: B
Rationale: Hydrogen bonding allows water to dissolve many polar and ionic
substances, making it essential for biological systems.
11. Which property of water helps stabilize body temperature?
A. High density
B. High specific heat
C. Low polarity
D. Low surface tension
Correct Answer: B
Rationale: High specific heat allows water to absorb and release heat with
minimal temperature change.