AP BIOLOGY

Detailed explanation-1: -The first bacteria evolved more than 3 billion years ago and dominated the biosphere continually thereafter, shaping the environment in which animals would eventually evolve more than 2 billion years later (Narbonne 2005; Knoll 2011).

Detailed explanation-2: -Viruses, then, may have existed before bacteria, archaea, or eukaryotes (Figure 4; Prangishvili et al. 2006). Most biologists now agree that the very first replicating molecules consisted of RNA, not DNA.

Detailed explanation-3: -Defining Bacteria They were one of the first living cells to evolve and have spread to inhabit a variety of different habitats including hydrothermal vents, glacial rocks, and other organisms. They share characteristics with eukaryotic cells including the cytoplasm, cell membrane, and ribosomes.

Detailed explanation-4: -The ancestors of bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago.

Detailed explanation-5: -Earth has been a bacterial world for at least the last 3.5 billion years. In the oceans of our young planet, bacteria were among the first forms of life to emerge. Long before plants or animals had evolved, bacterial colonies flourished and grew.