Explain how cell signaling pathways in prokaryotes and eukaryotes demonstrate conservation of major features over time

Eukaryotic cells and prokaryotic cells are distant living things as they have differences even on the cellular level (i.e. the presence of a nuclear membrane, rRNA differences). Although even with these differences, the molecular biology especially for cellular metabolism and signaling pathways are conserved. One of the more common signaling pathway that is seen in both prokaryotes and eukaryotes is the G-protein pathway which involves a seven pass or serpentine protein with an intrinsic GTPase activity (hence the name) which then signal either the production of cAMP or IP3/DAG wherein these second messengers will activate certain protein kinases that will phosphorylate specific proteins and enzymes and regulate cells’ function. 

enzyme speed up the reactions

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.