,CHEM 210 FINAL Exam | Biochemistry |
Portage Learning | Q & A | 2026 Edition
1. What are the three primary ways that biochemists study biological organisms?
A) Structure-function relationships, metabolic reactions, and cellular communication
B) Genetic inheritance, protein synthesis, and energy production
C) Cellular respiration, photosynthesis, and DNA replication
D) Enzyme regulation, hormone signaling, and immune response
Correct Answer: Structure-function relationships, metabolic reactions, and cellular communication
Rationale: Biochemists study the relationship between structure and function of biomolecules, the
chemical reactions of organisms (metabolism), and communication within and among organisms. These
three pillars form the foundation of biochemical inquiry and are essential for understanding life at the
molecular level.
2. Which of the following correctly distinguishes organic from inorganic compounds?
A) Organic compounds contain carbon; inorganic compounds do not
B) Organic compounds contain carbon bonded to hydrogen; inorganic compounds lack C-H bonds
C) Organic compounds are always found in living organisms; inorganic compounds are synthetic
D) Organic compounds are always covalent; inorganic compounds are always ionic
Correct Answer: Organic compounds contain carbon bonded to hydrogen; inorganic compounds lack C-H
bonds
Rationale: Organic chemistry is the study of carbon-containing compounds with carbon-hydrogen bonds.
Inorganic compounds generally lack C-H bonds, though they may contain carbon (e.g., carbon dioxide,
carbonates).
3. Which property of carbon makes it uniquely suited as the backbone of biological molecules?
A) Carbon has six valence electrons, allowing it to form six bonds
,B) Carbon can form stable covalent bonds, long chains, double/triple bonds, and ring structures
C) Carbon is the most abundant element in living organisms
D) Carbon forms only ionic bonds with other elements
Correct Answer: Carbon can form stable covalent bonds, long chains, double/triple bonds, and ring
structures
Rationale: Carbon has four valence electrons and forms stable covalent bonds, allowing it to create long
chains, double and triple bonds, and cyclic structures. This versatility makes carbon the ideal element for
the vast diversity of biological molecules.
4. What is the approximate bond angle of water, and what is its molecular geometry?
A) 109.5°, tetrahedral
B) 104.5°, bent
C) 120°, trigonal planar
D) 107.5°, trigonal pyramidal
Correct Answer: 104.5°, bent
Rationale: Water has a bent molecular geometry with a bond angle of approximately 104.5°. This
geometry arises from the two lone pairs of electrons on oxygen, which compress the H-O-H bond angle
from the ideal tetrahedral 109.5°.
5. Which property of water contributes to its role as the universal solvent in biological systems?
A) Its low molecular weight
B) Its polarity and ability to form hydrogen bonds
C) Its high specific heat capacity
D) Its ability to ionize completely
Correct Answer: Its polarity and ability to form hydrogen bonds
, Rationale: Water's polarity and hydrogen-bonding capacity allow it to dissolve a wide range of polar and
ionic substances. This property makes water an excellent solvent for biochemical reactions, which occur
in aqueous environments.
6. What is the pH of a solution with a hydrogen ion concentration of 1 × 10⁻⁹ M?
A) 5
B) 7
C) 9
D) 11
Correct Answer: 9
Rationale: pH = -log[H⁺]. For [H⁺] = 1 × 10⁻⁹ M, pH = -log(10⁻⁹) = 9. This solution is basic, as pH values
above 7 indicate basic conditions.
7. What is the Henderson-Hasselbalch equation used to calculate?
A) The rate of an enzyme-catalyzed reaction
B) The pH of a buffer solution given the pKa and ratio of conjugate base to acid
C) The equilibrium constant of a biochemical reaction
D) The free energy change of a metabolic pathway
Correct Answer: The pH of a buffer solution given the pKa and ratio of conjugate base to acid
Rationale: The Henderson-Hasselbalch equation (pH = pKa + log([A⁻]/[HA])) relates pH, pKa, and the
ratio of conjugate base to weak acid. It is essential for understanding buffer systems in biological fluids
such as blood.
8. Which buffer system is the primary regulator of human blood plasma pH?
A) Phosphate buffer system
Portage Learning | Q & A | 2026 Edition
1. What are the three primary ways that biochemists study biological organisms?
A) Structure-function relationships, metabolic reactions, and cellular communication
B) Genetic inheritance, protein synthesis, and energy production
C) Cellular respiration, photosynthesis, and DNA replication
D) Enzyme regulation, hormone signaling, and immune response
Correct Answer: Structure-function relationships, metabolic reactions, and cellular communication
Rationale: Biochemists study the relationship between structure and function of biomolecules, the
chemical reactions of organisms (metabolism), and communication within and among organisms. These
three pillars form the foundation of biochemical inquiry and are essential for understanding life at the
molecular level.
2. Which of the following correctly distinguishes organic from inorganic compounds?
A) Organic compounds contain carbon; inorganic compounds do not
B) Organic compounds contain carbon bonded to hydrogen; inorganic compounds lack C-H bonds
C) Organic compounds are always found in living organisms; inorganic compounds are synthetic
D) Organic compounds are always covalent; inorganic compounds are always ionic
Correct Answer: Organic compounds contain carbon bonded to hydrogen; inorganic compounds lack C-H
bonds
Rationale: Organic chemistry is the study of carbon-containing compounds with carbon-hydrogen bonds.
Inorganic compounds generally lack C-H bonds, though they may contain carbon (e.g., carbon dioxide,
carbonates).
3. Which property of carbon makes it uniquely suited as the backbone of biological molecules?
A) Carbon has six valence electrons, allowing it to form six bonds
,B) Carbon can form stable covalent bonds, long chains, double/triple bonds, and ring structures
C) Carbon is the most abundant element in living organisms
D) Carbon forms only ionic bonds with other elements
Correct Answer: Carbon can form stable covalent bonds, long chains, double/triple bonds, and ring
structures
Rationale: Carbon has four valence electrons and forms stable covalent bonds, allowing it to create long
chains, double and triple bonds, and cyclic structures. This versatility makes carbon the ideal element for
the vast diversity of biological molecules.
4. What is the approximate bond angle of water, and what is its molecular geometry?
A) 109.5°, tetrahedral
B) 104.5°, bent
C) 120°, trigonal planar
D) 107.5°, trigonal pyramidal
Correct Answer: 104.5°, bent
Rationale: Water has a bent molecular geometry with a bond angle of approximately 104.5°. This
geometry arises from the two lone pairs of electrons on oxygen, which compress the H-O-H bond angle
from the ideal tetrahedral 109.5°.
5. Which property of water contributes to its role as the universal solvent in biological systems?
A) Its low molecular weight
B) Its polarity and ability to form hydrogen bonds
C) Its high specific heat capacity
D) Its ability to ionize completely
Correct Answer: Its polarity and ability to form hydrogen bonds
, Rationale: Water's polarity and hydrogen-bonding capacity allow it to dissolve a wide range of polar and
ionic substances. This property makes water an excellent solvent for biochemical reactions, which occur
in aqueous environments.
6. What is the pH of a solution with a hydrogen ion concentration of 1 × 10⁻⁹ M?
A) 5
B) 7
C) 9
D) 11
Correct Answer: 9
Rationale: pH = -log[H⁺]. For [H⁺] = 1 × 10⁻⁹ M, pH = -log(10⁻⁹) = 9. This solution is basic, as pH values
above 7 indicate basic conditions.
7. What is the Henderson-Hasselbalch equation used to calculate?
A) The rate of an enzyme-catalyzed reaction
B) The pH of a buffer solution given the pKa and ratio of conjugate base to acid
C) The equilibrium constant of a biochemical reaction
D) The free energy change of a metabolic pathway
Correct Answer: The pH of a buffer solution given the pKa and ratio of conjugate base to acid
Rationale: The Henderson-Hasselbalch equation (pH = pKa + log([A⁻]/[HA])) relates pH, pKa, and the
ratio of conjugate base to weak acid. It is essential for understanding buffer systems in biological fluids
such as blood.
8. Which buffer system is the primary regulator of human blood plasma pH?
A) Phosphate buffer system
