A major part of the fossil records is made up of calcium carbonate and calcium phosphate coming from the animals' _______ that had evolved during the Cambrian period.

The eukaryotes cells might have evolved when a large anaerobic amoeboid prokaryote ingested small aerobic bacteria and stabilized them instead of digesting them. This idea is called:

The "Great Oxidation Event" resulted in the evolution of cellular respiration in organisms due to the availability of which of the following gases?