Question

why does the plasma cell have a well developed endoplasmic reticulum with lots of ribosomes 

Answer 1

Answer:Within the cell, the endoplasmic reticulum synthesizes lipids and proteins. ... Proteins that are made in the cell for use by the cell-for instance, as channels in the plasma membrane-are made by the free ribosomes that dot the cytoplasm. Two types of endoplasmic reticulum are found in the eukaryotic cell.

Answer 2

Since plasma cells make your antibodies, they need to produce a lot of protein. Also because the nucleus makes a lot of products to make proteins you need a large Golgi Body. How ER's relate to this: to do protein synthesis you need ribosomes and to have ribosomes you need the rough ER!