Life first evolved in the primordial oceans of Earth approximately four billion years ago. The first life forms were prokaryotes, or non-nucleated unicellular organisms, which divided in two domains, the Bacteria and Archaea. They lived around hot...

Organisms which are completely dependent upon photosynthesis. They cannot use organic compounds for growth in the...

Photoautotrophs (Gk: photo = light, auto = self, troph = nourishment) are organisms that carry out photosynthesis. Using energy from sunlight, carbon dioxide and water are converted into organic materials to be used in cellular functions such as...