All of these are evidence of a common evolutionary ancestry for cell signaling except 1. both bacteria and eukaryotic cells have receptors for intercellular signaling in their cell membranes

2.both plant and animal cells participate in cell junctioning

3. both plant and animal cell plastids code for cell membrane receptors

4. both unicellular bacteria and yeast have complex cell-signaling systems that use chemical messengers

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population.b) the separated population is small, and genetic drift occurs.c) the isolated population is exposed to different selection pressures than the ancestral population.d) different mutations begin to distinguish the gene pools of the separated populations.e) gene flow between the two populations is extensive.