Who propsed that the first form of life could have come from pre-existing non-living organic molecules?

Options

A. S.L. Miller
B. Oparin and Haldane
C. Charles Darwin
D. Alfred Wallace

Explanation

**Step-by-Step Text Solution:**

1. **Identify the Question**: The question asks for the scientist(s) who proposed that the first form of life could have originated from pre-existing non-living organic molecules.

2. **Recall Relevant Theories**: The theory that relates to the origin of life from non-living organic molecules is known as the theory of chemical evolution.

3. **Identify Key Scientists**: The scientists associated with this theory are Alexander Oparin and J.B.S. Haldane. Oparin was Russian, and Haldane was English.

4. **Understand the Theory**: Oparin and Haldane proposed that before life could exist, various types of biomolecules (like nucleic acids, proteins, lipids, etc.) must have formed through chemical reactions in the early Earth's reducing atmosphere.

5. **Describe the Conditions of Early Earth**: The early Earth had unstable climatic conditions, including volcanic activity and electrical discharges, which contributed to the formation of these biomolecules from inorganic constituents.

6. **Conclusion**: Therefore, according to Oparin and Haldane, the first living cells must have formed from the aggregation of these pre-existing organic molecules, leading to the emergence of life.

**Final Answer**: Oparin and Haldane proposed that the first form of life could have come from pre-existing non-living organic molecules.

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