Class 11 Biology Chapter 2 Biological Classification – Revision Notes

Quick revision notes for Class 11 Biology Chapter 2 (Biological Classification). These Class 11 Biology Chapter 2 notes are ideal for quick revision just before exams.

Five Kingdoms (Whittaker, 1969)

• Monera: prokaryotic.
• Protista: unicellular eukaryotic.
• Fungi: heterotrophic, chitin cell wall, hyphae/mycelium.
• Plantae: autotrophic, cellulose cell wall.
• Animalia: heterotrophic, no cell wall.

Non-Cellular Entities

• Viruses: nucleic acid + protein coat, obligate parasites.
• Viroids: free RNA only, no protein coat (Diener).
• Lichens: alga/cyanobacterium + fungus symbiosis.

One-Line Summary

Biological classification organizes life into five kingdoms based on cell structure, nutrition, and organization, while viruses, viroids, and lichens are treated as special non-cellular or symbiotic entities outside this scheme.

Written by Satish

NCERTBooks.org is an independent educational resource run by a small team focused on making official NCERT textbooks easy to find, read, and download for students, parents, and teachers across India. We are not affiliated with NCERT or the Ministry of Education -- we organise publicly available NCERT content by class and subject, verify links against official sources, and build tools (like our in-browser reader) that make studying more convenient. Every guide we publish is written and reviewed by our team based on the actual NCERT curriculum and syllabus.