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Class 11 | CBSE | BIOLOGY
REVISION SHEET | LAST MINUTE EXAM PREPARATION

ONE-PAGE REVISION SHEET 

Class 11 Biology – Chapter 1: The Living World
Section 1.1: Diversity in the Living World
— designed for last-day exam revision.

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ONE-PAGE REVISION SHEET

DIVERSITY IN THE LIVING WORLD

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🔹 Biodiversity

• Refers to the number and variety of living organisms on Earth

• Includes plants, animals, and microorganisms

• Known species: ~1.7–1.8 million

• New species are continuously being discovered

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🔹 Species

• Basic unit of classification

• Each distinct kind of organism represents a species

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🔹 Need for Scientific Naming

• Common names:

  • Vary from place to place

  • Cause confusion

• Scientific names:

  • Are universal

  • Give one organism → one name

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🔹 Nomenclature

• Process of scientific naming of organisms

• Based on internationally accepted rules

Codes of Nomenclature

• ICBN → Plants

• ICZN → Animals

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🔹 Binomial Nomenclature

• Given by Carolus Linnaeus

• Each organism has two names:

  1. Genus

  2. Specific epithet

Example

Mangifera indica

• Mangifera → Genus

• indica → Species

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🔹 Rules of Binomial Nomenclature (VERY IMPORTANT)

1. Names are Latin or Latinised

2. Written in italics (print) / underlined separately (handwritten)

3. Genus → Capital letter

4. Species → Small letter

5. Author’s name written after species

   • Example: Mangifera indica Linn.

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🔹 Classification

• Process of grouping organisms based on similarities

• Makes study of organisms easy and systematic

Examples of Groups

• Plants, Animals

• Mammals

• Dogs, Cats

• Wheat, Rice

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🔹 Taxa (singular: Taxon)

• Categories of classification

• Exist at different hierarchical levels

Examples

• Plants

• Animals

• Mammals

• Dogs

• Wheat

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🔹 Taxonomy

• Science of classification

• Includes:

  • Characterisation

  • Identification

  • Classification

  • Nomenclature

Basis of Modern Taxonomy

• External structure

• Internal structure

• Cell structure

• Development

• Ecological information

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🔹 Systematics

• Study of diversity + evolutionary relationships

• Derived from Latin word ‘systema’

• Linnaeus’ book: Systema Naturae

• Broader than taxonomy

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🔹 Key Differences (1-Mark Favorite)

Term	Meaning
Taxonomy	Naming & classification
Systematics	Classification + evolution
Taxon	Category of classification
Species	Basic unit

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 EXAM GOLD POINTS

✔ Definitions = direct NCERT language
✔ Rules of binomial nomenclature = high-frequency questions
✔ Always underline scientific names correctly
✔ Write examples to score full marks

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