Question

A hen's egg can be seen easily. Is it a cell or a group of cells?

Answer 1

The hen's egg is not a single cell. It is made up of a protein component usually called albumin and some extra fat in the yolk. There are a few cells located on yolk called blastoderm made up of blastomeres and actually, cleavage takes place in these cells. Cleavage is of different types in different animals and varies with the egg types. The blastoderm is a very small cluster of the cell, so small that is is difficult to see by naked eyes. The embryo forms by the cleavage in blastoderm and development takes place. The oocyte though is a single cell.