Which of the following cell forms the boundary of cytoplasm protected from outside by external shock?

UP CHO - 10 September 2021

Applied Anatomy

Easy

Appeared in: UP CHO - 10 September 2021

Explanation

The plasma membrane is a phospholipid bilayer that encloses the entire cell, forming a distinct boundary between the intracellular (cytoplasm) and extracellular environments.
One of its primary roles is to provide protection to the cell's internal components from physical and chemical damage from the outside.
It acts as a selectively permeable barrier, controlling which substances can enter and leave the cell, thus maintaining a stable internal environment (homeostasis).
The question asks for the structure that forms the boundary and protects the cytoplasm, which is the exact definition of the plasma membrane's function.

Option A: Peroxisomes are small, membrane-bound organelles located within the cytoplasm. They do not form the outer boundary of the cell.
Option B: A vacuole is a membrane-bound sac found within the cytoplasm, primarily used for storage. It is an internal component, not the outer boundary.
Option C: Lysosomes are organelles located inside the cytoplasm that contain digestive enzymes. They are the cell's 'recycling center,' not its outer wall.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cellular structure and function as background academic context rather than a clinical decision trigger.
Understanding the function of the plasma membrane is critical for safe nursing practice, especially in fluid and electrolyte management. Administering IV fluids that are not isotonic to blood (e.g., 0.9% NaCl) can damage or destroy red blood cells by disrupting their plasma membranes through osmosis.
Many drugs work by targeting receptors or transport proteins located on the plasma membrane. A nurse's understanding of this helps in comprehending drug mechanisms and potential side effects.
What if? - If a patient were given a hypotonic IV solution (e.g., sterile water), water would rush into their red blood cells, causing them to swell and burst (hemolysis), a life-threatening condition. This highlights the membrane's role as a semipermeable barrier.

How to Approach the Question

First, identify the key concepts in the question stem: 'boundary of cytoplasm' and 'protected from outside'.
This is a factual recall question about basic cell biology.
Consider the function of each option.
The plasma membrane is defined as the outer boundary of the cell.
Peroxisomes, vacuoles, and lysosomes are all organelles located inside the cytoplasm.
Therefore, only the plasma membrane fits the description of forming the outer, protective boundary.

Concept Tested & Keywords

Concept Tested: Cellular structure and function
Stem keywords: cell, boundary of cytoplasm, protected from outside, external shock
Lead-in keywords: Which of the following
Negative lead-in flag: false

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