What type of mutation is responsible for sickle cell disease and tay sachs disease?

The bottle neck effect is the answer to this question, hope that this would help you! 

Ifound this information on google “yes. they have a mouth and brain at one end and an anus at the opposite end. what characteristics distinguish an annelid from other worms? annelids have segmented bodies and a coelem which is a tube filled with fluid and contains most of the organs.“ i hope it you