Early Greek thinkers thought that units of life called spores were transferred to different planets including earth. Identify the term associated with the above.

Panspermia

The correct answer is Option (2)- Panspermia

Early Greek philosophers entertained the notion that life's building blocks, known as spores, could have been transported to various planets, including Earth. This idea, called "Panspermia," remains a favored concept for some astronomers. Additionally, there was a long-held belief that life could originate from decaying and decomposing matter, such as straw or mud. This concept was known as the theory of spontaneous generation.

Louis Pasteur by careful experimentation demonstrated that life comes only from pre-existing life. He showed that in pre-sterilised flasks, life did not come from killed yeast while in another flask open to air, new living organisms arose from ‘killed yeast’. Spontaneous generation theory was dismissed once and for all.

Russian scientist Oparin and British scientist Haldane proposed a hypothesis suggesting that the first life forms could have originated from pre-existing non-living organic molecules, such as RNA and proteins. They theorized that the formation of life was preceded by a process known as chemical evolution, during which diverse organic molecules were generated from inorganic constituents. The conditions on early Earth, including high temperatures, volcanic activity, and a reducing atmosphere containing gases like methane (CH₄) and ammonia (NH₃), were considered conducive to this process.

In summary, while spontaneous generation theory was definitively disproven by Pasteur, the question of life's origin on Earth led to the proposal of the theory of chemical evolution by Oparin and Haldane. This theory suggests that life could have arisen from non-living organic molecules in the conditions present on early Earth.