The Living World — BIOLOGY STD 11 Science — Question

1. Chemoautotrophs

Explanation:

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.