Biological Evolution MCQ - Practice Questions & Answers

Quick Facts

20 Questions around this concept.

Concepts Covered - 1

Biological Evolution

Continuing with the chemical evolution, the amino acids, sugars, glycerol, fatty acids of primitive ocean polymerized to form large macromolecules like proteins, carbohydrates and fats.
These complex compounds are the main components of the protoplasm of al living cells, their synthesis established the possibility of the origin of life in the primitive ocean.
According to Fox, the collection of organic macromolecules surrounded by a double-layered boundary called the microsphere was formed.
At later stages, the microspheres carrying the opposite electrical charges aggregated to form larger and denser colloidal systems called coacervates, as termed by Oparin.
Coacervates provided an environment for various reactions and could grow in size by absorbing substances dissolved in water.
These coacervates became more complex and created diversity amongst themselves.
Another important event in the origin of life was the formation of nucleic acids in the primitive ocean.
The nucleotides were formed by the combination of a pentose sugar, nitrogen bases and phosphoric acids. These molecules behaved like naked genes or free genes.
Due to aggregation properties of molecules, macromolecules of nucleo-proteins were formed by the combination of nucleotides and proteins.
A number of such free genes might have aggregated to form a single large unit that resembled the present-day virus and was named protovirus.
Before the gene aggregates could develop into anything like a cell, it was necessary that they produce enzymes.
With the gradual formation of enzymes, conditions were now favorable for the formation of the cell.
The earliest cell was very simple. There was no nucleus and resembled a prokaryotic cell.
The first cellular form of life did not possibly originate until about 2000 million years ago.
All life forms were in a water environment only.
This version of abiogenesis, i.e., the first form of life arose slowly through evolutionary forces from non-living molecules is accepted by the majority.