Question

Arrange the following events a, b, c, d of chemical evolution in correct sequence and select the option.
a) Transformation of heterotrophs into autotrophs.
b) Formation of amino acids, purines and pyrimidines.
c) Formation of proto-proteins.
d) Heavy elements like iron and nickel form the solid core of earth.

• A. c, a, b, d
• B. d, b, c, a
• C. a, c, d, b
• D. b, d, a, c

Hint:

Chemical evolution progressed from inorganic matter to simple organic molecules, then to complex biomolecules, and finally to living systems.

Answer 1

The Correct Option is B

Step 1: Early formation of the earth.
During the early history of the earth, heavy elements such as iron and nickel sank towards the center and formed the solid core of the earth. This was the earliest event.

Step 2: Formation of simple organic molecules.
As conditions on the primitive earth became suitable, simple organic compounds like amino acids, purines, and pyrimidines were formed from inorganic substances.

Step 3: Formation of complex macromolecules.
These simple organic molecules combined to form more complex molecules such as proto-proteins, which were essential for the origin of life.

Step 4: Evolution of metabolic pathways.
Initially, living organisms were heterotrophic. With time, some organisms evolved the ability to synthesize their own food, leading to the transformation of heterotrophs into autotrophs.

Step 5: Conclusion.
Thus, the correct chronological sequence of chemical evolution is d, b, c, a.