Why do cells need to harness the energy of 'falling electrons during the electron transport chain?

How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures

What is a dendrite and what does it do?

Blank is a rock with a find dark texture that makes up the oceanic crust