Question

Why was the primitive atmosphere of earth more beneficial to the origin of life than the modern atmosphere of earth?
A. The primitive atmosphere had a layer of ozone that shielded the first delicate cells.
B. The primitive atmosphere was a reducing one that facilitated the formation of complex substances from simple molecules.
C. The primitive atmosphere was an oxidising one that facilitated the formation of complex substances from simple molecules.
D. The primitive atmosphere had less free energy than the modem atmosphere, and thus newly formed organisms were less likely to be destroyed.

Answer 1

Hint: The atmospheres are the composition of various gases, particulates, and liquids. The atmospheric conditions are dynamic that redistribute heat and other forms of energy. The atmosphere provides important aspects for living things.

Complete answer:
The term primitive earth refers to the newly formed earth. At the time of its formation, the atmosphere of the earth was generally believed to have been reducing. This concept was first proposed by Oparin and further, it is discussed by Urey.
In an atmospheric condition in which oxidation takes place through the removal of oxygen as well as other oxidizing vapours is known as a reducing atmosphere. This type of atmospheric condition contained actively reducing gases such as hydrogen, carbon monoxide, and gases such as hydrogen sulfide and it would be oxidized by any oxygen present.
The primitive atmosphere of the earth was reducing the atmosphere where a little amount of oxygen was present. But the atmosphere was enriched with water vapor, carbon monoxide, carbon dioxide, nitrogen, and hydrogen. The UV and gamma radiations that come from the Sun were the main sources of energy for chemogenesis at the primitive earth. These radiations of the Sun bear energy quanta which are able to release electrons from atoms and cause the formation of highly reactive free radicals which in turn combine to form early organic compounds. In present-days, the ozone layer present in the atmosphere of the earth absorbs these UV and gamma rays.
DNA is essential to life and cannot exist in the presence of oxygen. DNA in the presence of oxygen makes life occurring by accidental random processes difficult if not impossible.
The formation of complex substances from simple molecules took place in the reducing atmosphere of primitive earth.

Therefore, the correct option is option B.

Note: The primitive earth refers to the early condition of the earth after its formation in the solar system. The atmospheric condition of the early earth is said to be reducing which refers to that the amount of oxygen present was too little. But this reducing condition of primitive earth was more beneficial to the formation of complex substances from simple molecules.