Which of the following plant parts is used as an explant to prepare virus-free plants?

The process of isolating a small embryo from a seed and growing it on a culture medium is known as:

During somatic hybridisation in plants,

What is the remaining part of a plant cell called after the digestion of its cell wall?

What is used as a culture medium for callus?

Select the correct sequence for the production of somatic hybrid plants in somatic hybridization.
$I -$ Isolation of protoplasts
$II -$ Digestion of cell wall
$III -$ Regeneration of somatic hybrid plants
$IV -$ Isolation of cells
$V -$ Fusion of protoplasts of two different varieties
$VI -$ Formation of hybrid protoplasts