While there isn't one single person credited with proposing the "biochemical theory of origin of life," the idea has been developed and refined over many years by various scientists. However, Alexander Oparin is widely considered the pioneer of this theory.

Here's why:

* 1924: Oparin published his book "The Origin of Life", which detailed his hypothesis about how life arose from non-living matter. His theory proposed that:

* Primordial Soup: The Earth's early atmosphere was rich in simple molecules like methane, ammonia, and water. These molecules, under the influence of lightning, ultraviolet radiation, and volcanic activity, could have combined to form complex organic molecules.

* Coacervates: These organic molecules could have then formed droplets called coacervates, which acted as protocells.

* Evolution of Life: Over time, these coacervates became more complex, eventually evolving into the first living cells.

J.B.S. Haldane independently proposed a similar theory around the same time.

Important Note: It's essential to understand that Oparin's theory was a foundational framework. Since then, research has progressed considerably, and scientists continue to investigate and refine our understanding of the origin of life. This includes studying the role of RNA in early life, the importance of hydrothermal vents, and the potential role of extraterrestrial molecules.