Q.Name the smallest known living cell, notable for being completely devoid of a cell wall.

[!TLDR]

Mycoplasma (PPLO) is the smallest known living cell and lacks a cell wall entirely.

[!ANSWER]

Mycoplasma (also called PPLO, pleuropneumonia-like organisms)

Mycoplasma, also known as PPLO (pleuropneumonia-like organisms), are the smallest known living cells, sometimes as small as about 0.3 micrometres, and are unique among bacteria in being completely devoid of a cell wall -- a feature which makes them structurally distinctive even among prokaryotes, most of which do possess a cell wall.

[!ANSWER]

Mycoplasma (also called PPLO, pleuropneumonia-like organisms)

Recall the specific organism named in the text as both the smallest cell and the exception lacking a cell wall.

Confusing Mycoplasma with a virus, since both are extremely small -- Mycoplasma is a true, if minimal, living cell.