Question

multiple choice question
the plasma membrane allows the movement of potassium ions across the membrane while inhibiting the transport of iron. this example demonstrates that the plasma membrane is a(n) ______ membrane.

options:

• cytoplasmic
• sempermeable (note: likely typo for semipermeable)
• tight junction
• vesicular

Explanation:

To solve this, we analyze each option:

• "Cytoplasmic" refers to the cytoplasm, not membrane permeability. Eliminate.
• "Semipermeable" (note: likely a typo for "semipermeable") membranes allow some substances (like potassium ions here) and block others (like iron here), matching the description.
• "Tight junction" is a cell - cell junction, not about membrane transport. Eliminate.
• "Vesicular" involves vesicles, not the selective transport described. Eliminate.

Answer:

B. semipermeable (assuming the option label for semipermeable is B; adjust label as per actual question's option numbering, but the concept is semipermeable membrane)