cell communication is critical for the function of both unicellular and multicellular eukaryotes. which of the following is likely true of cell signaling? (a) cell signaling uses the highest molecular weight molecules found in living cells. (b) cell signaling has largely been replaced by other cell functions in higher mammals. (c) similar cell signaling pathways in diverse eukaryotes are evidence of conserved evolutionary processes. (d) cell signaling functions mainly