Question

A scientist is comparing the outer structure of an onion cell, structure X, to the outer structure of a human skin cell, structure Y. Which generalization is true about the types of structures being examined?
Structure X is not living, and structure Y is living.
Structure X can be found in some human cells, and structure Y can be found in some plant cells.
Structure X is only found in plant cells, and structure Y is found in plant and animal cells.
Structure X is semipermeable, and structure Y is selectively permeable.

Answer 1

Correct answer: "Structure X is not living, and structure Y is living."

Explanation: The onion's outer layer is a cell wall, which is a nonliving, rigid support structure. The outer layer of a human skin cell is the plasma (cell) membrane, which is a living, functional part of the cell that regulates transport and communication. The other choices are incorrect because cell walls also occur in fungi and bacteria (so not only plant cells), and the cell wall is porous rather than acting as a selective/semipermeable membrane—the selective barrier function belongs to the plasma membrane.