WGU D390 Introduction to Human
Biology Objective Assessment Practice
Examination 2026–2027 | Comprehensive
Question Practice Test with Answers &
Rationales| Free Pdf Access
1. What is the basic structural and functional unit of the human body?
A. Cell
B. Tissue
C. Organ
D. Organ System
Correct Answer: A
Rationale: Cells are the smallest living units that perform all necessary life functions.
2. Which level of biological organization is composed of similar cells working together?
A. Tissue
B. Organ
C. Organ System
D. Organism
Correct Answer: A
Rationale: Tissues consist of groups of similar cells that perform a common function.
3. What is homeostasis?
A. Maintenance of a stable internal environment
B. Production of body heat only
C. Cell division process
D. Movement of blood through vessels
Correct Answer: A
,Rationale: Homeostasis allows the body to maintain optimal internal conditions despite
external changes.
4. Which organ system is primarily responsible for transporting oxygen, nutrients, and
wastes?
A. Cardiovascular System
B. Respiratory System
C. Skeletal System
D. Integumentary System
Correct Answer: A
Rationale: The cardiovascular system circulates blood throughout the body.
5. Which organelle is known as the "powerhouse of the cell"?
A. Mitochondrion
B. Nucleus
C. Ribosome
D. Golgi Apparatus
Correct Answer: A
Rationale: Mitochondria generate ATP, the primary energy source for cells.
6. What is the primary function of the nucleus?
A. Store and control genetic information
B. Produce ATP
C. Digest cellular waste
D. Synthesize lipids
Correct Answer: A
Rationale: The nucleus contains DNA and directs cellular activities.
7. Which molecule serves as the primary energy currency of cells?
A. ATP
B. DNA
, C. RNA
D. Glucose
Correct Answer: A
Rationale: ATP provides readily available energy for cellular processes.
8. Which type of tissue covers body surfaces and lines organs?
A. Epithelial Tissue
B. Muscle Tissue
C. Nervous Tissue
D. Connective Tissue
Correct Answer: A
Rationale: Epithelial tissue provides protection, absorption, and secretion.
9. Which tissue is responsible for movement?
A. Muscle Tissue
B. Nervous Tissue
C. Connective Tissue
D. Epithelial Tissue
Correct Answer: A
Rationale: Muscle tissue contracts to produce movement.
10. What is the primary function of connective tissue?
A. Support, protection, and binding of structures
B. Conduct nerve impulses
C. Produce movement only
D. Cover body surfaces
Correct Answer: A
Rationale: Connective tissue supports and connects other tissues and organs.
11. Which body system provides structural support and protection?
Biology Objective Assessment Practice
Examination 2026–2027 | Comprehensive
Question Practice Test with Answers &
Rationales| Free Pdf Access
1. What is the basic structural and functional unit of the human body?
A. Cell
B. Tissue
C. Organ
D. Organ System
Correct Answer: A
Rationale: Cells are the smallest living units that perform all necessary life functions.
2. Which level of biological organization is composed of similar cells working together?
A. Tissue
B. Organ
C. Organ System
D. Organism
Correct Answer: A
Rationale: Tissues consist of groups of similar cells that perform a common function.
3. What is homeostasis?
A. Maintenance of a stable internal environment
B. Production of body heat only
C. Cell division process
D. Movement of blood through vessels
Correct Answer: A
,Rationale: Homeostasis allows the body to maintain optimal internal conditions despite
external changes.
4. Which organ system is primarily responsible for transporting oxygen, nutrients, and
wastes?
A. Cardiovascular System
B. Respiratory System
C. Skeletal System
D. Integumentary System
Correct Answer: A
Rationale: The cardiovascular system circulates blood throughout the body.
5. Which organelle is known as the "powerhouse of the cell"?
A. Mitochondrion
B. Nucleus
C. Ribosome
D. Golgi Apparatus
Correct Answer: A
Rationale: Mitochondria generate ATP, the primary energy source for cells.
6. What is the primary function of the nucleus?
A. Store and control genetic information
B. Produce ATP
C. Digest cellular waste
D. Synthesize lipids
Correct Answer: A
Rationale: The nucleus contains DNA and directs cellular activities.
7. Which molecule serves as the primary energy currency of cells?
A. ATP
B. DNA
, C. RNA
D. Glucose
Correct Answer: A
Rationale: ATP provides readily available energy for cellular processes.
8. Which type of tissue covers body surfaces and lines organs?
A. Epithelial Tissue
B. Muscle Tissue
C. Nervous Tissue
D. Connective Tissue
Correct Answer: A
Rationale: Epithelial tissue provides protection, absorption, and secretion.
9. Which tissue is responsible for movement?
A. Muscle Tissue
B. Nervous Tissue
C. Connective Tissue
D. Epithelial Tissue
Correct Answer: A
Rationale: Muscle tissue contracts to produce movement.
10. What is the primary function of connective tissue?
A. Support, protection, and binding of structures
B. Conduct nerve impulses
C. Produce movement only
D. Cover body surfaces
Correct Answer: A
Rationale: Connective tissue supports and connects other tissues and organs.
11. Which body system provides structural support and protection?
