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.

Explanation:

1. Recall cell structure knowledge: Onion cells (plant cells) have a cell wall (structure X) and cell membrane. Human skin cells (animal cells) have a cell membrane (structure Y), no cell wall.
2. Analyze each option:

• Option 1: Cell wall (X) is non - living, cell membrane (Y) is living? No, cell membrane is living, but cell wall is non - living, but this option's wording is not the key distinction.
• Option 2: Cell wall (X) is not found in human cells, cell membrane (Y) is not found in plant cells? No, plant cells have cell membranes too.
• Option 3: Cell wall (X) is only in plant cells, cell membrane (Y) is in plant and animal cells. This matches the cell structure facts.
• Option 4: Cell wall is fully permeable (not semi - permeable), cell membrane is selectively permeable. So this is wrong.

Answer:

Structure X is only found in plant cells, and structure Y is found in plant and animal cells.