BIOL251 Human Anatomy and Physiology I w/Lab
2026/2027
150 Questions with Answers and Rationales
1. Which of the following best defines anatomy?
A) The study of how body structures function
B) The study of the structure of body parts and their relationships to one another
C) The study of disease processes in the body
D) The study of chemical reactions in living organisms
Answer: B
Rationale: Anatomy is the scientific discipline that investigates the structure of body parts
and how they relate to one another. Physiology is the study of function. While anatomy and
physiology are closely related, they represent distinct but complementary approaches to
understanding the human body .
2. The term "physiology" refers to:
A) The study of body structures
B) The study of the function of body parts
C) The study of tissue composition
D) The study of anatomical landmarks
Answer: B
Rationale: Physiology is the study of how the body and its parts work or function. It focuses
on the mechanisms of action and the vital functions of living organisms and their parts .
3. Which of the following represents the correct hierarchy of structural organization in the
human body from simplest to most complex?
A) Organ → Tissue → Cellular → Chemical → Organ System → Organismal
B) Chemical → Cellular → Tissue → Organ → Organ System → Organismal
C) Tissue → Cellular → Chemical → Organ → Organ System → Organismal
D) Cellular → Chemical → Tissue → Organ → Organ System → Organismal
Answer: B
Rationale: The levels of structural organization in the human body, from simplest to most
complex, are: chemical (atoms and molecules), cellular (cells), tissue (groups of similar cells),
organ (two or more tissue types working together), organ system (organs working together),
and organismal (the entire living individual) .
,4. Which organ system is responsible for protecting the body from environmental hazards
and helping regulate body temperature?
A) Skeletal system
B) Muscular system
C) Integumentary system
D) Lymphatic system
Answer: C
Rationale: The integumentary system (skin, hair, nails, and associated glands) provides
protection against environmental hazards, helps regulate body temperature through sweat
and blood flow regulation, and serves as a sensory interface with the environment .
5. A plane that divides the body into anterior and posterior sections is called a:
A) Sagittal plane
B) Frontal (coronal) plane
C) Transverse plane
D) Oblique plane
Answer: B
Rationale: The frontal (coronal) plane divides the body into anterior (front) and posterior
(back) sections. A sagittal plane divides the body into left and right portions. A transverse
plane divides the body into superior (upper) and inferior (lower) portions .
6. In the anatomical position, the palms of the hands face:
A) Posteriorly
B) Anteriorly
C) Laterally
D) Medially
Answer: B
Rationale: In the standard anatomical position, the body is erect with feet slightly apart,
palms facing forward (anteriorly), and thumbs pointed away from the body. This position
provides a consistent reference point for describing anatomical structures and their
relationships .
7. The directional term "proximal" means:
A) Closer to the midline of the body
B) Farther from the point of attachment to the trunk
C) Closer to the point of attachment to the trunk
D) Toward the back of the body
Answer: C
,Rationale: Proximal means closer to the point of attachment to the trunk or closer to the
origin of a structure. Distal means farther from the point of attachment. These terms are
particularly useful when describing structures of the limbs .
8. The body cavity that contains the brain is the:
A) Thoracic cavity
B) Abdominal cavity
C) Cranial cavity
D) Pelvic cavity
Answer: C
Rationale: The cranial cavity, a subdivision of the dorsal body cavity, houses and protects the
brain. The vertebral (spinal) cavity contains the spinal cord. The ventral body cavity includes
the thoracic, abdominal, and pelvic cavities .
9. Which of the following is an example of a negative feedback mechanism?
A) Blood clotting
B) Uterine contractions during childbirth
C) Regulation of blood glucose levels
D) Ovulation
Answer: C
Rationale: Negative feedback mechanisms work to maintain homeostasis by opposing or
reversing a change in a controlled condition. Blood glucose regulation is a classic example:
when blood glucose rises, insulin is released to lower it; when glucose falls, glucagon is
released to raise it. This maintains glucose levels within a normal range. Positive feedback
(ex: blood clotting and childbirth) amplifies the initial stimulus .
10. Positive feedback mechanisms:
A) Maintain homeostasis by reversing changes
B) Amplify the initial stimulus
C) Always result in disease
D) Are the most common type of feedback mechanism
Answer: B
Rationale: Positive feedback mechanisms amplify or enhance the initial stimulus, moving the
body further away from homeostasis. While less common than negative feedback, positive
feedback is important in specific processes such as blood clotting, childbirth (uterine
contractions), and milk ejection during breastfeeding .
11. The serous membrane lining the thoracic cavity walls is called the:
A) Visceral pleura
B) Parietal pleura
C) Visceral pericardium
, D) Peritoneum
Answer: B
Rationale: Serous membranes have two layers: parietal (lining the cavity walls) and visceral
(covering the organs). The parietal pleura lines the thoracic cavity walls, while the visceral
pleura covers the lungs. The pericardium surrounds the heart, and the peritoneum lines the
abdominopelvic cavity .
12. Which of the following elements is most abundant in the human body by weight?
A) Carbon
B) Hydrogen
C) Nitrogen
D) Oxygen
Answer: D
Rationale: Oxygen is the most abundant element in the human body, comprising
approximately 65% of body weight. It is a critical component of water and many organic
molecules. Carbon is the second most abundant, followed by hydrogen and nitrogen .
13. An atom with 6 protons, 6 neutrons, and 6 electrons has an atomic number of:
A) 6
B) 12
C) 18
D) 3
Answer: A
Rationale: The atomic number of an atom is equal to the number of protons in its nucleus.
This atom has 6 protons, so its atomic number is 6 (carbon). The mass number is the sum of
protons and neutrons (6 + 6 = 12) .
14. The bond formed when atoms share electrons equally is called a:
A) Ionic bond
B) Polar covalent bond
C) Nonpolar covalent bond
D) Hydrogen bond
Answer: C
Rationale: A nonpolar covalent bond occurs when electrons are shared equally between two
atoms of similar electronegativity. A polar covalent bond involves unequal sharing of
electrons. Ionic bonds involve the complete transfer of electrons from one atom to another .
15. Which type of chemical reaction involves the breakdown of larger molecules into smaller
ones?
2026/2027
150 Questions with Answers and Rationales
1. Which of the following best defines anatomy?
A) The study of how body structures function
B) The study of the structure of body parts and their relationships to one another
C) The study of disease processes in the body
D) The study of chemical reactions in living organisms
Answer: B
Rationale: Anatomy is the scientific discipline that investigates the structure of body parts
and how they relate to one another. Physiology is the study of function. While anatomy and
physiology are closely related, they represent distinct but complementary approaches to
understanding the human body .
2. The term "physiology" refers to:
A) The study of body structures
B) The study of the function of body parts
C) The study of tissue composition
D) The study of anatomical landmarks
Answer: B
Rationale: Physiology is the study of how the body and its parts work or function. It focuses
on the mechanisms of action and the vital functions of living organisms and their parts .
3. Which of the following represents the correct hierarchy of structural organization in the
human body from simplest to most complex?
A) Organ → Tissue → Cellular → Chemical → Organ System → Organismal
B) Chemical → Cellular → Tissue → Organ → Organ System → Organismal
C) Tissue → Cellular → Chemical → Organ → Organ System → Organismal
D) Cellular → Chemical → Tissue → Organ → Organ System → Organismal
Answer: B
Rationale: The levels of structural organization in the human body, from simplest to most
complex, are: chemical (atoms and molecules), cellular (cells), tissue (groups of similar cells),
organ (two or more tissue types working together), organ system (organs working together),
and organismal (the entire living individual) .
,4. Which organ system is responsible for protecting the body from environmental hazards
and helping regulate body temperature?
A) Skeletal system
B) Muscular system
C) Integumentary system
D) Lymphatic system
Answer: C
Rationale: The integumentary system (skin, hair, nails, and associated glands) provides
protection against environmental hazards, helps regulate body temperature through sweat
and blood flow regulation, and serves as a sensory interface with the environment .
5. A plane that divides the body into anterior and posterior sections is called a:
A) Sagittal plane
B) Frontal (coronal) plane
C) Transverse plane
D) Oblique plane
Answer: B
Rationale: The frontal (coronal) plane divides the body into anterior (front) and posterior
(back) sections. A sagittal plane divides the body into left and right portions. A transverse
plane divides the body into superior (upper) and inferior (lower) portions .
6. In the anatomical position, the palms of the hands face:
A) Posteriorly
B) Anteriorly
C) Laterally
D) Medially
Answer: B
Rationale: In the standard anatomical position, the body is erect with feet slightly apart,
palms facing forward (anteriorly), and thumbs pointed away from the body. This position
provides a consistent reference point for describing anatomical structures and their
relationships .
7. The directional term "proximal" means:
A) Closer to the midline of the body
B) Farther from the point of attachment to the trunk
C) Closer to the point of attachment to the trunk
D) Toward the back of the body
Answer: C
,Rationale: Proximal means closer to the point of attachment to the trunk or closer to the
origin of a structure. Distal means farther from the point of attachment. These terms are
particularly useful when describing structures of the limbs .
8. The body cavity that contains the brain is the:
A) Thoracic cavity
B) Abdominal cavity
C) Cranial cavity
D) Pelvic cavity
Answer: C
Rationale: The cranial cavity, a subdivision of the dorsal body cavity, houses and protects the
brain. The vertebral (spinal) cavity contains the spinal cord. The ventral body cavity includes
the thoracic, abdominal, and pelvic cavities .
9. Which of the following is an example of a negative feedback mechanism?
A) Blood clotting
B) Uterine contractions during childbirth
C) Regulation of blood glucose levels
D) Ovulation
Answer: C
Rationale: Negative feedback mechanisms work to maintain homeostasis by opposing or
reversing a change in a controlled condition. Blood glucose regulation is a classic example:
when blood glucose rises, insulin is released to lower it; when glucose falls, glucagon is
released to raise it. This maintains glucose levels within a normal range. Positive feedback
(ex: blood clotting and childbirth) amplifies the initial stimulus .
10. Positive feedback mechanisms:
A) Maintain homeostasis by reversing changes
B) Amplify the initial stimulus
C) Always result in disease
D) Are the most common type of feedback mechanism
Answer: B
Rationale: Positive feedback mechanisms amplify or enhance the initial stimulus, moving the
body further away from homeostasis. While less common than negative feedback, positive
feedback is important in specific processes such as blood clotting, childbirth (uterine
contractions), and milk ejection during breastfeeding .
11. The serous membrane lining the thoracic cavity walls is called the:
A) Visceral pleura
B) Parietal pleura
C) Visceral pericardium
, D) Peritoneum
Answer: B
Rationale: Serous membranes have two layers: parietal (lining the cavity walls) and visceral
(covering the organs). The parietal pleura lines the thoracic cavity walls, while the visceral
pleura covers the lungs. The pericardium surrounds the heart, and the peritoneum lines the
abdominopelvic cavity .
12. Which of the following elements is most abundant in the human body by weight?
A) Carbon
B) Hydrogen
C) Nitrogen
D) Oxygen
Answer: D
Rationale: Oxygen is the most abundant element in the human body, comprising
approximately 65% of body weight. It is a critical component of water and many organic
molecules. Carbon is the second most abundant, followed by hydrogen and nitrogen .
13. An atom with 6 protons, 6 neutrons, and 6 electrons has an atomic number of:
A) 6
B) 12
C) 18
D) 3
Answer: A
Rationale: The atomic number of an atom is equal to the number of protons in its nucleus.
This atom has 6 protons, so its atomic number is 6 (carbon). The mass number is the sum of
protons and neutrons (6 + 6 = 12) .
14. The bond formed when atoms share electrons equally is called a:
A) Ionic bond
B) Polar covalent bond
C) Nonpolar covalent bond
D) Hydrogen bond
Answer: C
Rationale: A nonpolar covalent bond occurs when electrons are shared equally between two
atoms of similar electronegativity. A polar covalent bond involves unequal sharing of
electrons. Ionic bonds involve the complete transfer of electrons from one atom to another .
15. Which type of chemical reaction involves the breakdown of larger molecules into smaller
ones?
