Why do autotrophs always occupy the lowest level of ecological pyramids?

What re the two main phrases of the cell cycle.

What initially causes a nerve impulse? release of enzymes out of the neuron movement of chemicals into the dendrites of the neuron pathogens attacking the dendrites of the neuron red blood cells bathing the neuron

Prokaryotic and eukaryotic cells are different in many ways other than the presence or absence of a nucleus. if both archaebacteria and eubacteria are prokaryotic cells, then why are archaebacteria more closely related to eukaryotic cells than they are to eubacteria?