Biology · Evolution · NEET
| Source of life | Non-living matter | Pre-existing living organisms |
| Other name | Spontaneous generation / autobiogenesis | Theory of biogenesis |
| Status | Disproved (classical form) | Accepted for all present life |
| Key scientist | Believed by early thinkers (e.g. Aristotle) | Pasteur, Redi, Spallanzani |
| Example claim | Maggots from rotting meat | Microbes grow only from other microbes |
Yes. The old theory of abiogenesis is the same idea as spontaneous generation (also called autobiogenesis). It claimed living things could appear on their own from non-living material, for example maggots forming from rotting meat or frogs from mud. NEET treats these terms as the same classical idea, which was later disproved.
Louis Pasteur proved biogenesis and disproved abiogenesis. Using swan-neck flasks with boiled (sterilised) sugar-yeast broth, he showed no new life grew when air could enter but dust and microbes were trapped in the bend. Life only appeared when the broth was exposed to already-existing microbes. So new life comes only from pre-existing life.
This is the key NEET point. Biogenesis explains all later life but cannot explain the first cell. To fill that gap, Oparin and Haldane proposed chemical evolution: the first life arose slowly from non-living molecules under special early-Earth conditions. This is different from classical abiogenesis, so it is often called modern abiogenesis or chemical origin of life.
The Oparin-Haldane theory is a modern form of abiogenesis, but not the old spontaneous generation. It says the first life formed once from simple molecules through slow chemical steps on primitive Earth, not that living things keep appearing from mud or meat. After that first cell, biogenesis took over.
The evidence for biogenesis came from several scientists. Francesco Redi (covered meat, no maggots) and Lazzaro Spallanzani (boiled sealed broth) gave early proof, and Louis Pasteur gave the final, most famous proof with his swan-neck flask experiment. NEET most often links biogenesis with Pasteur.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Abiogenesis says life comes from non-living matter; biogenesis says life comes only from pre-existing living organisms.
Biogenesis is accepted for all present-day life. For the very first life on Earth, scientists accept chemical evolution (a modern, one-time abiogenesis), not classical spontaneous generation.
Pasteur's swan-neck flask experiment disproved classical abiogenesis and confirmed biogenesis.
NEET regularly asks who proposed or disproved these ideas and how chemical evolution differs from spontaneous generation. Knowing the difference prevents common option traps in the Origin of Life topic.
