MCAT CHEMICAL AND PHYSICAL FOUNDATIONS OF
BIOLOGICAL SYSTEMS NEWEST 2025-2026 UPDATE
REAL PRACTICE EXAM QUESTIONS & CORRECT
ANSWERS | ALREADY GRADED A+
Content Covered (Most Frequently Tested Topics)
General chemistry: atomic structure, periodic trends,
bonding, stoichiometry, thermochemistry, kinetics,
equilibrium, acids and bases
Organic chemistry: functional groups, reactions,
stereochemistry, spectroscopy
Physics: kinematics, work and energy, fluids,
electrostatics, circuits, waves
Biochemistry foundations: amino acids, enzymes,
metabolism basics
Biological systems physical principles: transport,
membranes, fluid flow, diffusion
A 25-year-old patient presents with fatigue during moderate exercise.
Blood tests show reduced hemoglobin concentration. Oxygen transport
in blood depends on diffusion and pressure gradients. The physician
reviews oxygen diffusion across capillaries and the relationship between
pressure, volume, and gas concentration.
, 1. Which gas law best describes the inverse relationship between
pressure and volume of oxygen in the lungs during breathing?
A. Charles’s law
B. Boyle’s law
C. Dalton’s law
D. Avogadro’s law
Answer: Boyle’s law
Boyle’s law states that pressure and volume are inversely proportional
at constant temperature. As lung volume increases during inhalation,
pressure decreases, allowing air to enter.
2. Oxygen diffuses from alveoli into blood primarily due to
differences in:
A. temperature
B. density
C. partial pressure
D. viscosity
Answer: partial pressure
Gas diffusion across membranes is driven by differences in partial
pressure according to Fick’s law.
3. If the radius of a capillary doubles, blood flow through that vessel
will increase by approximately:
A. 2 times
B. 4 times
C. 8 times
D. 16 times
,Answer: 16 times
According to Poiseuille’s law, flow is proportional to the fourth power of
the radius (r⁴). Doubling radius increases flow by 2⁴ = 16.
4. Which intermolecular force primarily stabilizes oxygen binding to
hemoglobin?
A. Covalent bonding
B. Ionic bonding
C. Coordination bonding with iron
D. Metallic bonding
Answer: Coordination bonding with iron
Oxygen binds reversibly to the Fe²⁺ ion in the heme group through a
coordination bond.
5. A decrease in blood pH reduces hemoglobin’s oxygen affinity. This
phenomenon is known as:
A. Bohr effect
B. Doppler effect
C. Zeeman effect
D. Joule–Thomson effect
Answer: Bohr effect
The Bohr effect describes reduced oxygen affinity of hemoglobin under
acidic conditions or high CO₂.
6. Which quantum number describes the shape of an orbital?
A. principal quantum number
B. magnetic quantum number
, C. azimuthal quantum number
D. spin quantum number
Answer: azimuthal quantum number
The azimuthal (l) quantum number determines the shape of orbitals
such as s, p, d.
7. The strongest intermolecular force between water molecules is:
A. London dispersion
B. dipole–dipole interaction
C. hydrogen bonding
D. ionic bonding
Answer: hydrogen bonding
Water molecules form hydrogen bonds due to highly polar O–H bonds.
8. Which element has the greatest electronegativity?
A. carbon
B. oxygen
C. nitrogen
D. fluorine
Answer: fluorine
Fluorine is the most electronegative element in the periodic table.
9. What is the pH of a solution with hydrogen ion concentration of 1
× 10⁻³ M?
A. 1
B. 2
BIOLOGICAL SYSTEMS NEWEST 2025-2026 UPDATE
REAL PRACTICE EXAM QUESTIONS & CORRECT
ANSWERS | ALREADY GRADED A+
Content Covered (Most Frequently Tested Topics)
General chemistry: atomic structure, periodic trends,
bonding, stoichiometry, thermochemistry, kinetics,
equilibrium, acids and bases
Organic chemistry: functional groups, reactions,
stereochemistry, spectroscopy
Physics: kinematics, work and energy, fluids,
electrostatics, circuits, waves
Biochemistry foundations: amino acids, enzymes,
metabolism basics
Biological systems physical principles: transport,
membranes, fluid flow, diffusion
A 25-year-old patient presents with fatigue during moderate exercise.
Blood tests show reduced hemoglobin concentration. Oxygen transport
in blood depends on diffusion and pressure gradients. The physician
reviews oxygen diffusion across capillaries and the relationship between
pressure, volume, and gas concentration.
, 1. Which gas law best describes the inverse relationship between
pressure and volume of oxygen in the lungs during breathing?
A. Charles’s law
B. Boyle’s law
C. Dalton’s law
D. Avogadro’s law
Answer: Boyle’s law
Boyle’s law states that pressure and volume are inversely proportional
at constant temperature. As lung volume increases during inhalation,
pressure decreases, allowing air to enter.
2. Oxygen diffuses from alveoli into blood primarily due to
differences in:
A. temperature
B. density
C. partial pressure
D. viscosity
Answer: partial pressure
Gas diffusion across membranes is driven by differences in partial
pressure according to Fick’s law.
3. If the radius of a capillary doubles, blood flow through that vessel
will increase by approximately:
A. 2 times
B. 4 times
C. 8 times
D. 16 times
,Answer: 16 times
According to Poiseuille’s law, flow is proportional to the fourth power of
the radius (r⁴). Doubling radius increases flow by 2⁴ = 16.
4. Which intermolecular force primarily stabilizes oxygen binding to
hemoglobin?
A. Covalent bonding
B. Ionic bonding
C. Coordination bonding with iron
D. Metallic bonding
Answer: Coordination bonding with iron
Oxygen binds reversibly to the Fe²⁺ ion in the heme group through a
coordination bond.
5. A decrease in blood pH reduces hemoglobin’s oxygen affinity. This
phenomenon is known as:
A. Bohr effect
B. Doppler effect
C. Zeeman effect
D. Joule–Thomson effect
Answer: Bohr effect
The Bohr effect describes reduced oxygen affinity of hemoglobin under
acidic conditions or high CO₂.
6. Which quantum number describes the shape of an orbital?
A. principal quantum number
B. magnetic quantum number
, C. azimuthal quantum number
D. spin quantum number
Answer: azimuthal quantum number
The azimuthal (l) quantum number determines the shape of orbitals
such as s, p, d.
7. The strongest intermolecular force between water molecules is:
A. London dispersion
B. dipole–dipole interaction
C. hydrogen bonding
D. ionic bonding
Answer: hydrogen bonding
Water molecules form hydrogen bonds due to highly polar O–H bonds.
8. Which element has the greatest electronegativity?
A. carbon
B. oxygen
C. nitrogen
D. fluorine
Answer: fluorine
Fluorine is the most electronegative element in the periodic table.
9. What is the pH of a solution with hydrogen ion concentration of 1
× 10⁻³ M?
A. 1
B. 2
