to stimulate muscle contraction, acetylcholine is released from the into the synaptic cleft.

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 are the four stages of cell signaling?

Which of these structures are found in both plant ans animal cells?