question_answer

Which types of cells absent in sponges?

A)  Trophocytes    

B)  Myocytes

C)  Archeocytes    

D)  Cnidocytes

Correct Answer: D

Solution :

Cnidocytes or stringing cells are spherical or oval cells found in entire epidermis except that of basal disc and are found only in cnidarians. Archeocytes trophocytes and myocytes. Are found in sponges. Archeocytes have short and blunt lobose pseudopodia, a large nucleus and a large quantity of RNA. These are undifterentiated totipotem cells. Which may differentiate into all other types of cells. Trophocyles serve to supply nutrient to the developing cell and hence also called nurse cells. Myocytes are long, slender, highly contractile spindle-shaped cells. These form a circular sphincter arround the osculum and serve to close or open it as required.