Mass extinctions

A) are the result of humans damaging the natural environment.
B) are the result of humans exploiting wildlife and using pesticides.
C) occurred in cycles when organisms fail to evolve.
D) have occurred about 4 or 5 times in fossil record.
E) require life to evolve again from protocells.

Mass Extinctions

Events in Earth's history where large numbers of species become extinct in a relatively short period of time.

Fossil Record

The collection of all known fossils and their placement in rock formations and sedimentary layers, providing evidence of past life and evolutionary histories.

Protocells

Simple, self-organized, prebiotic structures that are considered the precursors to living cells.