NCERT Solutions for Class 9th Science Chapter 12 Patterns in Life: Diversity and Classification
Updated on 2026-09-19
About this chapter
Biodiversity is the whole variety of living organisms. India is rich in it because its habitats range from the Himalayas to the Thar desert to the Western Ghats; species found nowhere else are endemic (Nilgiri tahr, lion-tailed macaque, Nepenthes khasiana , Neelakurinji), and regions rich in endemics that have also lost much habitat are biodiversity hotspots . Organisms are classified on seven kinds of evidence: external features, mode of nutrition, internal structures, cell structure, ecological role, reproduction and genetic similarity. Shared features point to a common ancestor . The system grew step by step — Aristotle (habitat) → two kingdom (1758, Linnaeus) → three kingdom (1866, Haeckel, adds Protista) → four kingdom (1938, Copeland, adds Monera) → five kingdom (1969, Whittaker) : M
- Chapter opener
- Let us compare and classify
- .3.1 Some criteria to classify living organisms
- Let us read a case study
- Let us study
- Let us explore
- Let us make
- .6.2 Kingdom Protista
- Lichens as bioindicators
- Pteridophyta
Quick revision
| Term | What it means | Example from the chapter | Where it appears |
|---|---|---|---|
| Biodiversity | The whole variety of living organisms on the Earth | Microscopic algae to giant trees; Himalayas to Andaman coral reefs | Chapter opener, 12.1 |
| Endemic species | A species found naturally in one region and nowhere else | Nilgiri tahr, lion-tailed macaque, Nepenthes khasiana, Neelakurinji | 12.1, Fig. 12.1 |
| Biodiversity hotspot | Region with many endemic species that has also lost much of its habitat | Western Ghats, Indo-Burma, Himalayas, Sundaland | 12.1 |
| Prokaryote / Eukaryote | Cell without / with a membrane-bound nucleus | Bacteria (pro) vs Amoeba (eu) | 12.5, Fig. 12.5 |
| Monera | Unicellular prokaryotes | Bacteria, Archaea, Cyanobacteria; Lactobacillus, Rhizobium | 12.6.1 |
| Protista | Unicellular eukaryotes, no cell wall or a cellulose one | Amoeba, Paramecium, Chlamydomonas, Euglena | 12.6.2 |
| Fungi | Mostly multicellular heterotrophic eukaryotes, cell wall of chitin | Yeast, Aspergillus, Penicillium, mushroom | 12.6.3 |
| Mycelium | Network of fine filaments through which a fungus absorbs nutrients | Bread mould growing on damp bread | 12.6.3 |
| Thallus | A simple plant body not divided into root, stem and leaf | Spirogyra (Thallophyta) | 12.6.4 |
| Rhizoids | Root-like anchoring structures of bryophytes (not true roots) | Moss, Marchantia | 12.6.4 |
| Vascular tissue | Xylem carries water, phloem carries food | First seen in Pteridophyta (fern stem, Fig. 12.11b) | 12.6.4 |
| Notochord | Flexible rod-shaped supporting structure; basis of the animal split | Present in Amphioxus (protochordate); precursor of the vertebral column | 12.6.5 |
| Bilateral symmetry | Body divisible into two halves along one plane; head and tail ends | Platyhelminthes onwards | 12.6.5 |
| Exoskeleton / Endoskeleton | Hard covering outside / skeleton inside the body | Crab, insect (exo); starfish, vertebrates (endo) | Fig. 12.16 |
| Binomial nomenclature | Two-part Latin scientific name: Genus + species | Panthera tigris, Mangifera indica | 12.8 |
| Fossil | Preserved remains of plants and animals in layers of rock, sand and mud | Older layers → simpler organisms; work of Birbal Sahni | 12.9 |
Exercises
- Chapter opener — Think It Over Page 228
- Let us compare and classify — Activity 12.1 Page 230 – 231
- .3.1 Some criteria to classify living organisms — Pause and Ponder Page 23112
- Let us read a case study — Activity 12.2 Page 232
- Let us study — Activity 12.3 Page 234
- Let us explore — Activity 12.4 Page 235
- Let us make — Activity 12.5 Page 235 – 236
- .6.2 Kingdom Protista — Pause and Ponder Page 23612
- Lichens as bioindicators — Bridging Science and Society Page 237
- Let us explore — Activity 12.6 Page 238
- Pteridophyta — In-text Questions Page 238
- Let us compare — Activity 12.7 Page 238
- Gymnosperms — Pause and Ponder Page 238
- Let us discuss — Activity 12.8 Page 239
- Let us study — Activity 12.9 Page 239 – 240
- Porifera and Cnidaria — In-text Questions Page 241
- Annelida and Arthropoda — In-text Questions Page 242
- Arthropoda — Pause and Ponder Page 242
- Forests as barriers against disasters — Bridging Science and Society Page 244
- .7.1 The hierarchical nature of classification — In-text Questions Page 24412
- .9 Fossils as Evidence / 12.10 Biodiversity Under Threat — Pause and Ponder Page 24712
- Phumdis of Loktak Lake and the Sangai deer — Bridging Science and Society Page 248
- End-of-chapter questions — Revise, Reflect, Refine Page 249 – 251
- Project work — The Journey Beyond Page 251
- An open question — The Quest Continues… Page 251