There are two kinds of cells, prokaryotic and eukaryotic, both of which consist of cytoplasm enclosed within a membrane and contain many biomolecules such as proteins and nucleic acids.Cells reproduce through a process of cell division, in which the parent cell divides into two or more daughter cells.

Fossils are the preserved remains or traces of organisms.

Since there is no unequivocal definition of life, most current definitions in biology are descriptive.

and replicate by creating multiple copies of themselves through self-assembly.

However, viruses do not metabolize and they require a host cell to make new products.

Founded in 2002 by Nobel Laureate Carl Wieman, the Ph ET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations.

Ph ET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery.

Another theory is that life is the property of ecological systems, and yet another is elaborated in complex systems biology, a branch or subfield of mathematical biology.

Abiogenesis describes the natural process of life arising from non-living matter, such as simple organic compounds.

To survive in most ecosystems, life must often adapt to a wide range of conditions.

Some microorganisms, called extremophiles, thrive in physically or geochemically extreme environments that are detrimental to most other life on Earth.

Earth's current life may have descended from an RNA world, although RNA-based life may not have been the first.