<prompt> Fixed time is required for which steps of cell cycleSMG1G2  <response>: Actually option A,B,D are answers Ref Grays anatomy 38the p55 The time taken for S,G1,and M phases are similar for most cell types, occupying about 6,4,2 hrs The duration of G1 shows considerable variation.it can be as sho as 2 hrs in rapidly dividing cells like embryonic tissue or as long as 12hrs in some adult tissues G1 phase is most variable because,in this phase cells are not committed to DNA replication . They can either enter resting state or progress to next cell division 