A protoplast is a  plant cell

Protoplast is a cell without cell wall or unit mass of protoplasm surrounded by cell membrane. In animals, the cell itself is a protoplast. In plants, the protoplast is surrounded by a cell wall.

(1) Cell division is one of the phases of cell cycle. In general, the division phase is a mitotic phase.

(3) The contant inside a living cell excluding the membraneous phase is protoplasm.

(4) A cell without nucleus is described as enucleated cell. Few cells loose nuclei at maturity, e.g., sieve cells, RBC of man, sieve tube elements.