SCI 221 Exam 1 V1 | SCI 221 Human
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 1) | Nightingale
College
1. Which of the following best describes the concept of homeostasis within the human body?
A. A state of complete physiological stasis where no changes occur.
B. A process that primarily uses positive feedback to prevent organ failure.
C. The body’s ability to maximize energy expenditure during periods of rest.
D. The maintenance of a relatively stable internal environment despite external changes.
Correct Answer: D
Rationale: Homeostasis refers to the body’s ability to maintain a stable internal
environment even when the external environment changes significantly. It involves a
dynamic state of equilibrium where internal conditions are kept within narrow, healthy
ranges. Most homeostatic mechanisms utilize negative feedback loops to correct deviations
from a set point.
2. In a negative feedback loop, what is the specific role of the ‘effector’?
A. To detect changes in the internal environment.
B. To carry out the response that restores the variable to its set point.
,C. To process information and determine the appropriate response.
D. To serve as the communication link between the brain and the spinal cord.
Correct Answer: B
Rationale: The effector is the component of a control system that receives output from the
control center and produces a response. This response acts to negate or reduce the
stimulus, thereby returning the system to homeostasis. Typical examples of effectors
include muscles that contract or glands that secrete hormones.
3. Which cellular organelle is primarily responsible for the production of ATP via aerobic
respiration?
A. Mitochondria
B. Golgi apparatus
C. Lysosome
D. Smooth endoplasmic reticulum
Correct Answer: A
Rationale: Mitochondria are often referred to as the powerhouses of the cell because they
generate the majority of adenosine triphosphate (ATP). They utilize oxygen and nutrients
to perform cellular respiration, converting chemical energy into a form usable by the cell.
Cells with high metabolic demands, such as muscle cells, contain a high density of these
organelles.
, 4. A red blood cell is placed in a hypertonic solution. What will happen to the cell?
A. The cell will lose water and shrink (crenation).
B. The cell will swell and potentially burst (hemolysis).
C. The cell will remain unchanged in size and shape.
D. The cell will actively pump solutes out to equalize pressure.
Correct Answer: A
Rationale: In a hypertonic solution, the concentration of solutes outside the cell is higher
than inside the cell. Because water moves toward areas of higher solute concentration via
osmosis, water will exit the red blood cell. This loss of intracellular fluid causes the cell to
shrink, a process known as crenation.
5. What is the primary function of the phospholipid bilayer in the plasma membrane?
A. To facilitate the active transport of large proteins.
B. To provide a rigid structural framework for the cell wall.
C. To catalyze metabolic reactions occurring on the cell surface.
D. To act as a selectively permeable barrier to water-soluble substances.
Correct Answer: D
Rationale: The phospholipid bilayer forms the fundamental structure of the plasma
membrane, featuring hydrophobic tails and hydrophilic heads. This arrangement creates a
barrier that prevents most water-soluble (polar) molecules from passing through freely.
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 1) | Nightingale
College
1. Which of the following best describes the concept of homeostasis within the human body?
A. A state of complete physiological stasis where no changes occur.
B. A process that primarily uses positive feedback to prevent organ failure.
C. The body’s ability to maximize energy expenditure during periods of rest.
D. The maintenance of a relatively stable internal environment despite external changes.
Correct Answer: D
Rationale: Homeostasis refers to the body’s ability to maintain a stable internal
environment even when the external environment changes significantly. It involves a
dynamic state of equilibrium where internal conditions are kept within narrow, healthy
ranges. Most homeostatic mechanisms utilize negative feedback loops to correct deviations
from a set point.
2. In a negative feedback loop, what is the specific role of the ‘effector’?
A. To detect changes in the internal environment.
B. To carry out the response that restores the variable to its set point.
,C. To process information and determine the appropriate response.
D. To serve as the communication link between the brain and the spinal cord.
Correct Answer: B
Rationale: The effector is the component of a control system that receives output from the
control center and produces a response. This response acts to negate or reduce the
stimulus, thereby returning the system to homeostasis. Typical examples of effectors
include muscles that contract or glands that secrete hormones.
3. Which cellular organelle is primarily responsible for the production of ATP via aerobic
respiration?
A. Mitochondria
B. Golgi apparatus
C. Lysosome
D. Smooth endoplasmic reticulum
Correct Answer: A
Rationale: Mitochondria are often referred to as the powerhouses of the cell because they
generate the majority of adenosine triphosphate (ATP). They utilize oxygen and nutrients
to perform cellular respiration, converting chemical energy into a form usable by the cell.
Cells with high metabolic demands, such as muscle cells, contain a high density of these
organelles.
, 4. A red blood cell is placed in a hypertonic solution. What will happen to the cell?
A. The cell will lose water and shrink (crenation).
B. The cell will swell and potentially burst (hemolysis).
C. The cell will remain unchanged in size and shape.
D. The cell will actively pump solutes out to equalize pressure.
Correct Answer: A
Rationale: In a hypertonic solution, the concentration of solutes outside the cell is higher
than inside the cell. Because water moves toward areas of higher solute concentration via
osmosis, water will exit the red blood cell. This loss of intracellular fluid causes the cell to
shrink, a process known as crenation.
5. What is the primary function of the phospholipid bilayer in the plasma membrane?
A. To facilitate the active transport of large proteins.
B. To provide a rigid structural framework for the cell wall.
C. To catalyze metabolic reactions occurring on the cell surface.
D. To act as a selectively permeable barrier to water-soluble substances.
Correct Answer: D
Rationale: The phospholipid bilayer forms the fundamental structure of the plasma
membrane, featuring hydrophobic tails and hydrophilic heads. This arrangement creates a
barrier that prevents most water-soluble (polar) molecules from passing through freely.
