Basis of Classification

• Biodiversity — millions of species; need systematic classification.
• Basis: body design, level of organisation, germ layers, symmetry, coelom, notochord.
• Hierarchy — Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
• Binomial nomenclature — Genus species (Linnaeus); universal scientific names.

1. Why classify — organise knowledge; study evolution relationships; identify organisms.
2. Early groups — Aristotle: plants/herbs/shrubs/trees; animals with/without red blood.
3. Levels of organisation — cellular → tissue → organ → organ system.
4. Germ layers — diploblastic vs triploblastic.
5. Body cavity (coelom) — acoelomate, pseudocoelomate, coelomate.
6. Notochord — basis for vertebrates vs invertebrates.
7. NCERT Ch. 7 — five kingdoms; scientific naming.
8. Real world — Homo sapiens; Mangifera indica (mango).

Writing scientific name of human and mango correctly

Step 1 — Human: **Homo sapiens** — genus Homo capitalised, species sapiens lowercase.
Step 2 — Italicised (or underlined when handwritten).
Step 3 — Mango: **Mangifera indica** — genus Mangifera, species indica.
Step 4 — Same name worldwide regardless of local language.
Conclusion: binomial nomenclature avoids confusion of common names.

• Writing species name with capital letter (only genus capitalised).
• Misconception: scientific names vary by country (universal).
• Confusing genus and species order.
• Using common names in scientific classification (ambiguous).
• Forgetting Whittaker's five kingdom basis (cell type, body organisation, nutrition).

• Why do we need classification?
• Write scientific name of pea (Pisum sativum) correctly.
• List the hierarchy levels from kingdom to species.
• Name two criteria used for classification.

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