Revision Notes for Class 9 Biology: Diversity in Living Organisms
Access comprehensive revision notes for Diversity in Living Organisms using the CBSE Class 9 Biology Diversity in Living Organisms Notes Set 02. Designed to align with the 2026-27 academic syllabus for Class 9 Biology, these concept summaries help students streamline their exam preparation and review complex topics efficiently.
Review Diversity in Living Organisms for Class 9 Biology
Access the complete concept summary PDF for Diversity in Living Organisms below. Regular review of these targeted notes builds familiarity with complex Class 9 Biology themes and helps secure higher marks in final school evaluations.
Why We Classify Living Things
Classification groups organisms by similarities and differences. It makes the huge variety of life easy to study and shows how groups are related.
Taxonomy is the branch that identifies, names and classifies organisms.
Early Systems
Aristotle grouped animals by habitat and by the presence of red blood. Linnaeus, the father of taxonomy, gave two kingdoms, Plantae and Animalia.
Haeckel suggested three kingdoms by adding Protista (1866), Copeland suggested four by separating Monera (1966), and Whittaker proposed five kingdoms (1969): Monera, Protista, Fungi, Plantae and Animalia.
Woese and others later split Monera into Archaebacteria and Eubacteria, giving six kingdoms.
Taxonomic Hierarchy and Naming
The ranks run Kingdom, Phylum (Division in plants), Class, Order, Family, Genus and Species. Species is the basic unit.
In binomial nomenclature the first word is the genus (capital letter) and the second the species (small letter), for example Rana tigrina. Scientific names are in Latin.
The Five Kingdoms at a Glance
| Kingdom | Cell type | Main features | Examples |
|---|---|---|---|
| Monera | Prokaryotic, unicellular | No nucleus or organelles | Bacteria, blue-green algae |
| Protista | Eukaryotic, mostly unicellular | Mostly aquatic, move by cilia, flagella or pseudopodia | Amoeba, Paramecium, Euglena, diatoms |
| Fungi | Eukaryotic | Non-green, absorb food, saprophytic or parasitic, body of hyphae | Mucor, Rhizopus, yeast |
| Plantae | Eukaryotic, multicellular | Chlorophyll, make food, cellulose cell wall | Algae to flowering plants |
| Animalia | Eukaryotic, multicellular | Heterotrophic, no cell wall | Sponges to mammals |
Viruses
A virus has a core of DNA or RNA inside a protein coat (capsid). It has no cytoplasm or metabolism of its own and multiplies only inside a living host cell, so it behaves as living inside the host and non-living outside.
Bacteriophages infect bacteria. HIV causes AIDS.
Plant Kingdom
| Group | Body | Vascular tissue | Seeds | Examples |
|---|---|---|---|---|
| Thallophyta | Undivided thallus | Absent | No | Algae, fungi, lichens |
| Bryophyta | Flat green thallus or leafy stem | Absent | No | Riccia, Marchantia, moss |
| Pteridophyta | Root, stem and leaves | Present | No | Selaginella, Equisetum, ferns |
| Gymnosperms | Root, stem and leaves | Present | Naked | Cycas, Pinus |
| Angiosperms | Root, stem and leaves | Present | Enclosed in fruit | Pea, wheat, rose |
Bryophytes need water for fertilisation and are called the amphibians of the plant kingdom. Angiosperms are divided into dicots (two cotyledons, reticulate venation, tap root) and monocots (one cotyledon, parallel venation, fibrous roots).
Animal Kingdom: Invertebrate Phyla
| Phylum | Key features | Examples |
|---|---|---|
| Protozoa | Unicellular, contractile vacuole for osmoregulation | Amoeba, Paramecium |
| Porifera | Pores and canal system, collar cells, no tissues | Sycon, Spongilla |
| Cnidaria | Radial symmetry, stinging cells (nematocysts) | Hydra, Aurelia |
| Platyhelminthes | Flat body, one opening, flame cells | Planaria, Taenia |
| Aschelminthes | Round body, complete gut, pseudocoelom | Ascaris, Wuchereria |
| Annelida | Segmented body, true coelom, nephridia | Earthworm, Nereis, leech |
| Arthropoda | Jointed legs, chitinous exoskeleton, largest phylum | Prawn, scorpion, insects |
| Mollusca | Soft body, shell, ctenidia | Pila, Octopus, Unio |
| Echinodermata | Spiny skin, tube feet, water vascular system | Starfish, sea urchin |
Phylum Chordata
Chordates have a notochord, a dorsal hollow nerve cord, pharyngeal gill slits and a post-anal tail at some stage. Vertebrates replace the notochord with a vertebral column.
Vertebrate classes: Cyclostomata (jawless, lamprey), Chondrichthyes (cartilaginous fish, shark), Osteichthyes (bony fish, rohu), Amphibia (frog, 3-chambered heart), Reptilia (snake, usually 3-and-a-half chambers), Aves (birds, 4 chambers, warm-blooded) and Mammalia (mammary glands, 4 chambers, warm-blooded).
Free study material for Science
Diversity in Living Organisms Concepts and Summary for Class 9 Biology
About Diversity in Living Organisms Revision Notes
Access structured revision notes for Diversity in Living Organisms designed in alignment with the latest CBSE curriculum for Class 9 Biology. These summaries help clarify core themes and support effective daily study.
How to Use These Revision Notes
Cross-reference your comprehension with comprehensive NCERT solutions for Class 9 to ensure absolute clarity across all sub-topics in this chapter.
Enhance Practice with MCQs and Worksheets
Follow up your revision by attempting the interactive online Biology MCQ test and practice worksheets for this chapter to verify your mastery. All platform resources are free to access.
FAQs
You can download the teacher prepared revision notes for CBSE Class 9 Biology Diversity in Living Organisms Notes Set 02 from StudiesToday.com. These notes are designed as per 2026-27 academic session to help Class 9 students get the best study material for Biology.
Yes, our CBSE Class 9 Biology Diversity in Living Organisms Notes Set 02 include 50% competency-based questions with focus on core logic, keyword definitions, and the practical application of Biology principles which is important for getting more marks in 2026 CBSE exams.
Yes, our CBSE Class 9 Biology Diversity in Living Organisms Notes Set 02 provide a detailed, topic wise breakdown of the chapter. Fundamental definitions, complex numerical formulas and all topics of CBSE syllabus in Class 9 is covered.
These notes for Biology are organized into bullet points and easy-to-read charts. By using CBSE Class 9 Biology Diversity in Living Organisms Notes Set 02, Class 9 students fast revise formulas, key definitions before the exams.
No, all study resources on StudiesToday, including CBSE Class 9 Biology Diversity in Living Organisms Notes Set 02, are available for immediate free download. Class 9 Biology study material is available in PDF and can be downloaded on mobile.