Question

First life on earth was
A) Chemoautotrophs
B) Autotrophs
C) Photoautotrophs
D) None of these

Answer 1

Evidence suggests that life on earth first existed 3.5 billion years ago. All of the known life forms share related molecular mechanisms that suggest that all of them have developed from a common ancestor.

Complete answer:
The most common hypothesis that is accepted regarding the origin of life on earth is the Miller-Urey experiment along with the work of Sidney fox. It stated that the conditions on primitive earth were such that it favored chemical reactions that resulted in the synthesis of amino acids and other organic compounds along with inorganic compounds. Primitive earth was dominated mostly by microorganisms that could survive without oxygen because the environment of primitive earth was reducing. Release of oxygen was brought about by cyanobacteria that resulted in the change of earth’s environment to an oxidizing one. Because oxygen could not be tolerated by the majority of the organisms in primitive earth this led to a major evolutionary change and finally led to the development of major plant and animal species that were the permanent members to occupy earth thereafter. The first life on earth was chemoautotrophs that could utilize the organic matter in the environment to carry out photosynthesis and thus make their own food. Chemoautotrophs were then followed by chemoheterotrophs that could not produce their own food.

Hence the correct answer is (A) Chemoautotroph.

Note: The origin of life on earth is a highly debated topic with many scientists giving many hypotheses. Life on earth has been known to develop from organic molecules and the first genetic material to be developed was RNA.