Question

Identify the correct order of appearance of the following organisms on the surface of earth.

I. Eukaryotes

II. Heterotrophic organisms

III. Metazoa

IV. Photosynthetic organisms

• A. II, I, IV, III
• B. II, I, III, IV
• C. II, IV, I, III
• D. IV, I, II, III
• E. IV, II, I, III

Answer 1

The correct option is C II, IV, I, III

First living organisms on earth were chemoheterotrophs (II) that do not perform oxygenic photosynthesis and used available organic molecules as source of carbon and energy source. Due to limited supply of organic compounds, organisms evolved photosystem to capture sunlight to be used as source of energy thereby leading to origin of photoautotrophs (IV). Both of these were prokaryotes and gradually increasing complexity of body organization lead to evolution of eukaryotes (I). Metazoa (also known as Animalia) includes multicellular eukaryotic organisms which appeared after unicellular eukaryotes (III).

Therefore, the correct answer is option C.