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Revision Notes

Evidences and Theories of Biological Evolution — Revision Notes

ICSE · Class 12 · Biology

Evidences and Theories of Biological Evolution revision notes for ICSE Class 12 Biology: 4 topics in quick points.

104 questions44 flashcards4 formulas & key relations5 concepts

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A comparative labeled diagram of the skeletal structure of forelimbs in different vertebrates (e.g., human, whale, bat, cheetah), illustrating their common anatomical plan despite different functions,
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Key Topics to Revise

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1. Evidences of Organic Evolution

  • Evolution is supported by multiple independent lines of evidence.
  • The major evidences are palaeontology, morphology and anatomy, embryology, cell biology and biochemistry, molecular genetics, and geographical distribution.
  • These evidences show that present-day organisms arose by gradual change from pre-existing forms.
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2. Palaeontological Evidence

  • Fossils are the relics of former living plants or animals preserved in rocks.
  • Fossils are mostly found in sedimentary rocks.
  • Palaeontology is the study of fossils.
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3. Fossil Series, Mass Extinction, and Geological Time Scale

  • The horse fossil series is Eohippus → Mesohippus → Merychippus → Equus.
  • Eohippus was about 30 cm high with four digits in the fore limb and three in the hind limb.
  • Mesohippus was about 60 cm high with three digits in each leg, and the weight was supported mainly by the middle digit.
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4. Comparative Anatomy: Homology, Analogy, Vestigial Organs, Connecting Links, Atavism

  • Homologous organs have different functions but similar embryogenic origin and development.
  • Homology indicates common ancestry and is the result of divergent evolution.
  • Analogous organs perform the same function, have superficial resemblance, but different origin.

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Key Concepts

Fossils are the remains or tracesImportant fossil types include petrificationFossil age is estimated by radioactiveThe horse evolved through successive fossilArchaeopteryx lithographica lived in the Jurassic

Frequently Asked Questions

What are the important topics in Evidences and Theories of Biological Evolution for ICSE Class 12 Biology?
Key topics in Evidences and Theories of Biological Evolution include Evidences of Organic Evolution, Palaeontological Evidence, Fossil Series, Mass Extinction, and Geological Time Scale, Comparative Anatomy: Homology, Analogy, Vestigial Organs, Connecting Links, Atavism. Study these first, then practise questions on each for the ICSE Class 12 board exam.
How should I revise Evidences and Theories of Biological Evolution for the ICSE Class 12 board exam?
Learn the core ideas first, then work through the 104 practice questions on Evidences and Theories of Biological Evolution. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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