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BIOL251 HUMAN ANATOMY & PHYSIOLOGY I Original Practice Questions with
Answers & Rationales
SECTION 1: CHEMISTRY AND CELLULAR BIOLOGY
1. Which of the following is the basic unit of matter?
A) Molecule
B) Atom
C) Cell
D) Tissue
Answer: B
Rationale: The atom is the smallest unit of matter that retains
the properties of an element. Molecules are made of atoms;
cells are made of molecules; tissues are made of cells.
2. The atomic number of an element is determined by the
number of:
A) Neutrons
B) Electrons
C) Protons
D) Protons + Neutrons
Answer: C
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Rationale: The atomic number equals the number of protons in
the nucleus, which defines the element.
3. Which subatomic particle has a negative charge?
A) Proton
B) Neutron
C) Electron
D) Nucleus
Answer: C
Rationale: Electrons carry a negative charge. Protons are
positive; neutrons are neutral.
4. Isotopes of an element differ in the number of:
A) Protons
B) Electrons
C) Neutrons
D) All subatomic particles
Answer: C
Rationale: Isotopes have the same number of protons (same
element) but different numbers of neutrons.
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5. Which type of chemical bond involves the transfer of
electrons?
A) Covalent bond
B) Hydrogen bond
C) Ionic bond
D) Van der Waals force
Answer: C
Rationale: Ionic bonds form when electrons are transferred
from one atom to another, creating charged ions that attract.
6. A covalent bond involves:
A) Transfer of electrons
B) Sharing of electrons
C) Attraction of opposite charges only
D) No electron involvement
Answer: B
Rationale: Covalent bonds form when atoms share electrons to
achieve stability.
7. Which of the following is a polar molecule?
A) O₂
B) CO₂
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C) H₂O
D) CH₄
Answer: C
Rationale: Water (H₂O) is polar—oxygen is more
electronegative, creating partial charges.
8. The pH of human blood is typically:
A) 6.8
B) 7.0
C) 7.35–7.45
D) 8.0
Answer: C
Rationale: Normal blood pH is slightly alkaline, between 7.35
and 7.45.
9. A solution with a pH of 3 is:
A) Neutral
B) Basic
C) Acidic
D) Alkaline
Answer: C
BIOL251 HUMAN ANATOMY & PHYSIOLOGY I Original Practice Questions with
Answers & Rationales
SECTION 1: CHEMISTRY AND CELLULAR BIOLOGY
1. Which of the following is the basic unit of matter?
A) Molecule
B) Atom
C) Cell
D) Tissue
Answer: B
Rationale: The atom is the smallest unit of matter that retains
the properties of an element. Molecules are made of atoms;
cells are made of molecules; tissues are made of cells.
2. The atomic number of an element is determined by the
number of:
A) Neutrons
B) Electrons
C) Protons
D) Protons + Neutrons
Answer: C
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Rationale: The atomic number equals the number of protons in
the nucleus, which defines the element.
3. Which subatomic particle has a negative charge?
A) Proton
B) Neutron
C) Electron
D) Nucleus
Answer: C
Rationale: Electrons carry a negative charge. Protons are
positive; neutrons are neutral.
4. Isotopes of an element differ in the number of:
A) Protons
B) Electrons
C) Neutrons
D) All subatomic particles
Answer: C
Rationale: Isotopes have the same number of protons (same
element) but different numbers of neutrons.
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5. Which type of chemical bond involves the transfer of
electrons?
A) Covalent bond
B) Hydrogen bond
C) Ionic bond
D) Van der Waals force
Answer: C
Rationale: Ionic bonds form when electrons are transferred
from one atom to another, creating charged ions that attract.
6. A covalent bond involves:
A) Transfer of electrons
B) Sharing of electrons
C) Attraction of opposite charges only
D) No electron involvement
Answer: B
Rationale: Covalent bonds form when atoms share electrons to
achieve stability.
7. Which of the following is a polar molecule?
A) O₂
B) CO₂
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C) H₂O
D) CH₄
Answer: C
Rationale: Water (H₂O) is polar—oxygen is more
electronegative, creating partial charges.
8. The pH of human blood is typically:
A) 6.8
B) 7.0
C) 7.35–7.45
D) 8.0
Answer: C
Rationale: Normal blood pH is slightly alkaline, between 7.35
and 7.45.
9. A solution with a pH of 3 is:
A) Neutral
B) Basic
C) Acidic
D) Alkaline
Answer: C
