Cheat sheet · Class 12 · CBSE · Science Biology
Evolution cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 12 · Biology
Cheat sheet
Chapter 6Evolution
Darwin: variation + natural selection + survival of the fittest.
1. Origin of Life
- Big Bang → Earth ~4.5 billion years ago.
- Oparin–Haldane: chemical evolution.
- Miller–Urey: amino acids from CH₄, NH₃, H₂, water vapour with sparks.
2. Evidence
- Palaeontology (fossils).
- Homologous organs (divergent): forelimbs of whale, bat, human.
- Analogous organs (convergent): wings of bird and insect.
- Industrial melanism (peppered moth).
3. Theories
Lamarck
use and disuse; inheritance of acquired characters.
Darwin
natural selection; branching descent.
de Vries
mutations cause speciation (saltation).
Hardy–Weinberg: p² + 2pq + q² = 1; disturbed by gene flow, drift, mutation, recombination, selection.
4. Human Evolution
- Dryopithecus, Ramapithecus → Australopithecus → Homo habilis → H. erectus → Neanderthals → H. sapiens.
- Brain size increased over time.
5. Key Points
- Adaptive radiation: Darwin's finches, Australian marsupials.
- Founder effect is a kind of genetic drift.
- Selection: stabilising, directional, disruptive.
- Coelacanth: a ‘living fossil’.
Remember: Miller–Urey | homologous vs analogous | Darwin | Hardy–Weinberg
Evolution: questions and notes
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