A protoplast is
A. A cell organelle
B. A cell with a wall
C. A single wall-less cell
D. Cell without nucleus

Hint:-Every plant cell has a definite cellulosic cell wall and the protoplast lies inside the cell wall except for some reproductive cells and free-floating cells in some fruit juices such as coconut water.

Complete Answer:-Protoplast is a biological term coined by Hanstein in 1880 to refer to the whole cell, minus the cell wall. Plant cell’s protoplasm consists of plasma-lemma and cytoplasm (fluid-like substance present inside the plasma membrane and consisting of nutrients, biomolecules and all the cell organelles) but no cell-wall. Protoplasts differ from spheroplasts in that they have completely lost their cell wall. Half of their cell wall is preserved by spheroplasts.
The peptidoglycan part of the cell wall has been eliminated in the case of Gram-negative bacterial spheroplasts for instance, but the outer membrane portion has not. Protoplasts may be produced by removing the cell wall by mechanical, chemical or enzymatic means from a plant, bacterial or fungal cells. However, those of interest to plant protoplast culture are experimentally produced by the removal of the cell wall from the artificially plasmolysed plant cells by either enzymatic or mechanical means. Protoplasts developed experimentally are known as isolated protoplasts.

Therefore the correct answer is option ‘C’ i.e, A protoplast is a single wall-less cell.

Note:- E.C. Cocking in I960, reported the enzymatic process for isolating protoplast in a large number of root tip cells of Lycopersicon esculentum using a concentrated solution of cellulase enzyme prepared from Myrothecium verrucaria fungal cultures to degrade the cell wall.