Question

First life on earth was

• A. Chemoautotrophs
  
• B. Autotrophs
  
• C. Photoautotrophs
  
• D. None of these

Answer 1

Answer: (A)

Chemoautotrophs

• Life began on earth some 3.8 million years ago and was initially occupied by the single-celled prokaryotic cells, such as bacteria. Multicellular organisms evolved over a billion years later.
• However, studies conducted on the genetic material suggest that single-celled living organisms that used carbon dioxide as a source of carbon and oxidized inorganic materials to extract energy were the first forms of life on earth.
• These organisms are called chemoautotrophs.

So, the correct answer is option A.