Which of the following best defines homeostasis?

• The process of maintaining a stable internal environment
• A state where all physiological variables remain constant
• The ability of an organism to adapt to any external change
• A state of dynamic disequilibrium

Answer explanation

Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes.

Which organ system is primarily responsible for transporting nutrients, gases, and wastes?

• Cardiovascular system
• Digestive system
• Nervous system
• Respiratory system

Answer explanation

The cardiovascular system transports oxygen, nutrients, and waste products throughout the body via the blood.

Which level of structural organization is immediately higher than the cellular level?

• Tissue
• Organ
• Organ system
• Chemical

Answer explanation

Tissues are groups of similar cells working together to perform a specific function.

Which type of feedback mechanism is involved in blood clotting?

• Positive feedback
• Negative feedback
• Neutral feedback
• Homeostatic balance

Answer explanation

Blood clotting is a positive feedback loop where an initial stimulus (platelet activation) enhances further platelet aggregation.

The smallest functional unit of life is the:

• Cell
• Molecule
• Atom
• Tissue

Answer explanation

The cell is the basic functional unit of life, performing all necessary biological functions.

What is the primary function of the integumentary system?

• Protect against external harm
• Provide structural support
• Regulate metabolism
• Facilitate gas exchange

Answer explanation

The integumentary system (skin, hair, nails) provides protection, regulates temperature, and prevents water loss.

Which term describes the ability of an organism to sense changes in its environment and react accordingly?

• Responsiveness
• Metabolism
• Differentiation
• Homeostasis

Answer explanation

Responsiveness is the ability to detect and respond to environmental changes.

Which body cavity contains the heart and lungs?

• Thoracic cavity
• Abdominal cavity
• Pelvic cavity
• Cranial cavity

Answer explanation

The thoracic cavity houses the heart and lungs, separated from the abdominal cavity by the diaphragm.

Which type of membrane lines body cavities that open to the exterior?

• Mucous membrane
• Synovial membrane
• Serous membrane
• Cutaneous membrane

Answer explanation

Mucous membranes line cavities that open to the exterior, such as the respiratory and digestive tracts.

What is the main purpose of negative feedback mechanisms?

• To maintain homeostasis by reducing deviations
• To amplify the original stimulus
• To eliminate physiological variables
• To trigger an immediate immune response

Answer explanation

Negative feedback mechanisms counteract deviations from