The statement below is followed by four options. Each option is related to the item in the statement, but only one is always true. Select the option that always holds and makes the statement true.
"A living cell always has ______."
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A cell membrane
The answer must hold for every living cell, without exception. An option that is present in most cases but can be missing in even one case is not always true.
Option (1) A cell wall — animal cells have no cell wall; only plant cells (and some others such as bacteria and fungi) have one.
Option (2) Chloroplasts — animal cells have no chloroplasts, and neither do the cells of a plant's roots.
Option (3) A nucleus — mature red blood cells of humans have no nucleus, and bacterial cells have no well-defined nucleus.
Option (4) A cell membrane — every cell is enclosed by a cell membrane (plasma membrane) that separates it from its surroundings, in plants, animals and bacteria alike, so this is always true.