Question

Given below are the sequence of events in the origin of life based on the Oparin-Haldane hypothesis.

Formation of monomeric units → I → II → Formation of non- cellular form of life → III

Identify I, II and III and choose the correct option.

Answer 1

Haldane and Oparin put forward their ideas regarding the origin of life on the earth.

They stated that the organic molecules were formed from the inorganic compounds due to the reducing atmosphere and ultraviolet radiation, which led to the origin of life. Their hypothesis is also called the theory of chemical evolution.

Chemical reactions between these gases and other inorganic molecules led to the formation of simple organic monomers like amino acids and nucleotides.

The simple organic molecules combined to form large complex organic molecules in ocean water like amino acids polymerised to form proteins. These organic molecules aggregated and the first non-cellular forms of life could have originated 3 billion years ago as giant molecules (RNA, Protein, Polysaccharides). The non-cellular life form eventually evolved into the first cellular form of life, about 2000 million years ago.

So, the correct sequence is :
Formation of monomeric units → Synthesis of polymers or macromolecules → Aggregation of organic molecules → Formation of non cellular form of life → Formation of cellular form of life.