Question

why do some cells have bigger/more of particular organelles then other and are there some examples ??

Answer 1

The size and number of organelles in different cell types are going to be related to the specialized function of that cell.

For instance, B lymphocytes are cells that are part of the adaptive immune system and one of their main jobs after activation by other cell types is to produce antigen specific antibodies. These antibodies are proteins that are produced on ribosomes associated with the endoplasmic reticulum. So, once a B lymphocyte receives a signal telling it to start making antibodies, it also generates a more extensive endoplasmic reticulum to assist in the higher demand for protein synthesis.

Another example would be muscle cells. These cells are packed with mitochondria because the energy demands of these cells are so high. Your muscle cells are expanding and contracting during each movement you make, and that requires a lot of energy. In comparison, a skin cell wouldn't need too many mitochondria (it would still need some!) because its energy demands just aren't that high.