Question

One classification scheme commonly used by biologists organizes life into ___ domains named ____. (This is the classification scheme we looked at in the lecture)

a) 2; Archaea and Bacteria
b) 3; Archaea, Bacteria, and Eukarya
c) 4; Animalia, Plantae, Fungi, Protista
d) 5; Prokaryota, Eukaryota, Archaea, Bacteria, Protista

Answer 1

Life is organized into three domains: Archaea, Bacteria, and Eukarya, based on genetic and cellular differences. This system supersedes the older five-kingdom model and reflects our current understanding of life's phylogenetic tree.

Step-by-step explanation:

The classification scheme commonly used by biologists organizes life into three domains named Archaea, Bacteria, and Eukarya. This system reflects the phylogenetic relationships between organisms based on genetic information and recognizes the fundamental differences in the cell structure of these groups.

Organisms within the domain Eukarya have cells that contain a nucleus and encompass kingdoms such as Animalia, Plantae, Fungi, and Protista. The domains Archaea and Bacteria are composed of unicellular prokaryotes, which do not have a cell nucleus. The Archaea are known for many including extremophiles, which live in harsh environments, while the Bacteria domain encompasses a vast diversity of bacterial life forms.

The three domains concept was a major shift from the previous five-kingdom system. It was proposed following the pioneering work of Carl Woese in the 1970s, who used ribosomal RNA sequences to reveal these deep evolutionary relationships. The recognition of these domains underscores that classification systems can evolve with new scientific discoveries.