AP BIOLOGY

Detailed explanation-1: -The answer came in the 1920’s when A.I. Oparin of Russia and J.B.S. Haldane of England independently presented compelling arguments that the origin of life could be explained, not as the result of rapid spontaneous generation of whole organisms in a few weeks, but from a long and gradual process of chemical evolution.

Detailed explanation-2: -The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old.

Detailed explanation-3: -Oparin and Haldane suggested that in the primitive reducing atmosphere of the earth (atmosphere containing methane, ammonia, and water vapor and very little oxygen) with energy sources like heat, lightning, UV rays, and abiotic carbon-containing compounds got converted to small organic compounds or monomers.

Detailed explanation-4: -The earliest time for the origin of life on Earth is at least 3.77 billion years ago, possibly as early as 4.28 billion years ago-not long after the oceans formed 4.5 billion years ago, and after the formation of the Earth 4.54 billion years ago.

Detailed explanation-5: -One ancient view of the origin of life, from Aristotle until the 19th century, is of spontaneous generation. This theory held that “lower” animals were generated by decaying organic substances, and that life arose by chance.