Read the Origin of the Universe and Life as a Sequence
Put cosmic history, the origin of Earth and chemical evolution in order; they are related but not the same event.
Origin of the Universe and Life is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Separate old explanations
The Big Bang model describes the origin and expansion of the Universe about 13.8 billion years ago. Earth formed much later. Spontaneous generation claimed that life arose repeatedly from decaying non-living matter; Pasteur’s experiments undermined that claim. Oparin and Haldane proposed chemical evolution before the first life.
Understand the Miller–Urey experiment
The experiment simulated a reducing atmosphere with methane, ammonia, hydrogen and water vapour, then supplied electrical energy. It produced organic molecules such as amino acids, showing that some building blocks could form abiotically under the model conditions.
Place the first life
In the standard textbook account, the earliest life arose in aquatic conditions. This is distinct from the much earlier origin of the Universe and the later formation of Earth.
Early replicators
Short RNA-like molecules are plausible early replicators because RNA can store sequence information and catalyse reactions. Smaller replicators are more plausible starting points than long, complex DNA molecules in a pre-cellular setting.
OlympIQ exam lens
- ✓Big Bang: Universe, about 13.8 billion years ago.
- ✓Spontaneous generation: life from decaying matter; experimentally challenged.
- ✓Oparin–Haldane: chemical evolution.
- ✓Miller–Urey: CH₄, NH₃, H₂ and water vapour + sparks.
- ✓Earliest life is placed in water in the source model.
The Miller–Urey experiment tested a chemical-evolution model; it did not create living cells.
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