In the last few decades, several taxonomic schemes have been used to describe life. One of the simplest divided life into prokaryotes and eukaryotes; that is, those organisms without nuclei went into one group and those with nuclei went into another, respectively. Another commonly used scheme divided life into five kingdoms: Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia. Keep in mind that classification schemes strive to show the evolutionary relationships between groups, and in recent years it has become apparent that the evolutionary relationships of prokaryotes are quite complex. One prokaryotic group, the Archaea, have some features that are more eukaryotic than prokaryotic. Although the Archaea lack a nucleus, their genetic organization is more like that of a eukaryote.