Test: Evolution - September 30, 2022 - NEET MCQ

The evolution starting from coacervates to the formation of a simple cell structure is known as Biological evolution. It is also called as Biogemy. This shows how cells originated during evolution.

Macromolecules synthesized in primitive oceans came together to form large colloidal drop like structures called protobionts. They grew up by absorbing molecules from the atmosphere. They also contained proteins, nucleic acids, lipids, etc.

Each and every protobiont was formed by a cluster of macromolecules. The basic building blocks of protobionts is macromolecules. These molecules were synthesized abiotically in the primitive ocean.

The first sole living organisms were Coacervates. According to Oparin, these coacervates gave rise to a cell. Oparin’s coacervates had the ability to grow and exhibit a simple form of metabolism. But a lipid membrane and reproduction were absent.

A scientist named Fox in 1957 discovered proteinoid microspheres which had a primitive membrane. In his research, he heated a mixture of amino acids at temperature 130 – 180°C and poured it into cold water with lipids. He found out that the microsphere got separated.

Zaug, Thomas Cech and Altman proved that RNA molecules have enzymatic activity. Ribozymes also called as RNA enzymes were able to replicate or produce primordial RNA. It was also believed that earth was an ‘RNA world’ about 4 billion years ago.

It was estimated about 3.9 billion years ago that, life originated as Eobionts (protocell). They evolved during the Precambrian era. They were anaerobic as well as heterotrophic in nature.

These prokaryotes were single-celled and consisted of naked DNA. They were chemoheterotrophs. Dependent on surrounding materials for food and energy.

Chemoautotrophs are the organisms that perform chemosynthesis for food and survival. They produce organic molecules from inorganic molecules. They are anaerobic in nature.

Photoautotrophs were anaerobic and utilized hydrogen from sources other than H₂O like H₂S. So, no oxygen was produced and the atmosphere was kept reducing. This type of photosynthesis was mainly done by planktonic sulfur bacteria.