Question

multiple choice question the structure marked a that functions as a selectively permeable membrane between the intracellular and extracellular fluid is the ______ endoplasmic reticulum cytoplasm nuclear envelope plasma membrane

Explanation:

To solve this, we analyze each option:

• Endoplasmic reticulum: Involved in protein/lipid synthesis, not the boundary between intra and extracellular fluid.
• Cytoplasm: The fluid inside the cell, not a membrane.
• Nuclear envelope: Separates nucleus from cytoplasm, not intra/extracellular.
• Plasma membrane: Defines the cell's boundary, selectively permeable between intracellular and extracellular fluid.

Answer:

D. plasma membrane