Question

The concept of chemical evolution is based on
A. Interaction of water, air and clay under intense heat
B. Effect of solar radiation on chemicals
C. Possible origin of life by combination of chemicals under suitable environmental conditions
D. Crystallisation of chemicals

Answer 1

Evolution is the change in the characteristics of any species that occur over a long period of time over several generations.

Complete Answer:
- Chemical evolution is the chemical changes that have taken place on the primitive Earth that gave rise to the first form of life.
- Chemical evolution means the origin of life from nonliving matter by the sequence of chemical reactions. Chemical evolution is also called abiogenesis.
- Chemical evolution was the first step in the evolution of the Earth. The period of chemical evolution lasted less than a billion years.
- Many steps of chemical evolution can now be reproduced in the laboratories. The aim of chemical evolution is to explain the transition between living and nonliving.
- The first living organisms evolved on the Earth are the prokaryotes (organisms that lack a well defined nucleus and membrane bound organelles, for example – bacteria).

Stages of chemical evolution:
- Russian scientist, Aleksandr wrote in “The origin of Life on Earth” that in the first stage of chemical evolution, molecules in the environment formed simple organic molecules such as amino acids.
- In the second stage of chemical evolution these simpler organic compounds such as amino acids accumulated together to form the larger structures such as proteins.
- In the third stage of chemical evolution these polymers such as proteins interacted with each other and got organized into aggregates which were called protobionts. Protobionts were not capable of reproduction but despite this they have all the properties of living beings.
- In the last step of chemical evolution protobionts developed the ability of reproduction and passing genetic information to their offspring.

Hence, option C is the correct option for this question.

Note: The higher organisms that are Eukaryotes get developed from the protobionts or prokaryotes by the process or evolution. The cell organelle Mitochondria also gets developed by protobionts when aerobic bacteria engulfed those protobionts.