When describing the cardiac cycle to a group of students, the instructor correlates heart sounds with events of the cycle. Which heart sound would the instructor explain as being associated with systole?

In the context of the neural impulse, which of the following is true about the depolarization of neuron membranes?

Q: a: in sexually reproducing animals, once fertilization of the egg takes place, the exists as a single cell until cell division begins

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