Question

which statement is a tenet of the cell theory?
a) plant and animal cells are identical.
b) all cells are too small to be seen without a microscope.
c) cells are only alive if they contain a nucleus.
d) cells are only made from preexisting cells.

Explanation:

The cell theory states that all cells come from pre - existing cells (one of the three main tenets: all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells come from pre - existing cells).

• Option 1: Plant and animal cells have different structures (e.g., plant cells have cell walls, chloroplasts; animal cells do not), so they are not identical.
• Option 2: The fact that cells are too small to be seen without a microscope is a characteristic of cells, not a tenet of cell theory.
• Option 3: Prokaryotic cells (like bacteria) do not have a nucleus but are still alive, so this statement is incorrect.
• Option 4: This matches the tenet of cell theory that cells arise from pre - existing cells.

Answer:

Cells are only made from preexisting cells.