Chapter 2: Biological Classification – Short Answer Type Questions

CBSE Class 11 Biology Short Answer Questions – Chapter 2: Biological Classification (NCERT Based)

Course Details

Course: CBSE Class 11 Biology
Syllabus: NCERT
Unit: Unit I – Diversity in Living World
Chapter: Chapter 2 – Biological Classification
CBSE Board Examination: Central Board of Secondary Education – Class 11 (School & Annual Examinations)

CBSE Class 11 Biology Chapter 2 Biological Classification – 40 Short Answer Questions with Answers (NCERT)

Section A: Five Kingdom Classification (Q1–Q10)

1. Explain the need for biological classification.
   Biological classification is required to organise the vast diversity of living organisms. It simplifies study, helps in identification, reveals evolutionary relationships, and enables systematic scientific communication worldwide.
2. Describe the basis of Five Kingdom Classification proposed by Whittaker.
   Whittaker’s classification is based on cell structure, body organisation, mode of nutrition, reproduction, and phylogenetic relationships, providing a natural and evolutionary system of classification.
3. List the five kingdoms of life.
   The five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia, each representing distinct organisational and nutritional characteristics.
4. Why is Whittaker’s classification considered superior to earlier systems?
   It considers multiple criteria including cell structure and evolutionary relationships, unlike earlier artificial systems based on limited observable characters.
5. Differentiate between prokaryotic and eukaryotic organisms.
   Prokaryotes lack a true nucleus and membrane-bound organelles, while eukaryotes possess a well-defined nucleus and organelles.
6. Why is mode of nutrition important in classification?
   Nutrition reflects metabolic complexity and ecological roles, helping differentiate autotrophs, heterotrophs, saprophytes, and parasites.
7. Why are viruses excluded from Five Kingdom Classification?
   Viruses are acellular and exhibit life-like properties only inside host cells, so they do not fit into cellular classification systems.
8. What is meant by phylogenetic classification?
   It classifies organisms based on evolutionary relationships and common ancestry rather than superficial similarities.
9. State one limitation of Five Kingdom Classification.
   It does not clearly distinguish between unicellular and multicellular eukaryotes in some cases.
10. Which kingdom includes the simplest organisms?
    Kingdom Monera includes the simplest prokaryotic organisms.

Section B: Kingdom Monera (Q11–Q18)

11. Describe the general characteristics of Kingdom Monera.
    Monerans are unicellular prokaryotes lacking a true nucleus and membrane-bound organelles. They may be autotrophic or heterotrophic and reproduce mainly by binary fission.
12. Explain the structure of a bacterial cell wall.
    The bacterial cell wall is composed of peptidoglycan, providing shape, rigidity, and protection against osmotic pressure.
13. Describe modes of nutrition in bacteria.
    Bacteria may be autotrophic (photosynthetic or chemosynthetic) or heterotrophic (saprophytic or parasitic).
14. What are cyanobacteria? Mention their importance.
    Cyanobacteria are photosynthetic prokaryotes that fix atmospheric nitrogen and contribute to soil fertility.
15. How do bacteria reproduce?
    Bacteria reproduce asexually through binary fission, where a single cell divides into two identical daughter cells.
16. What is Mycoplasma? Why is it unique?
    Mycoplasma is the smallest living cell and lacks a cell wall, making it resistant to certain antibiotics.
17. State the economic importance of bacteria.
    Bacteria aid in decomposition, nitrogen fixation, fermentation, and production of antibiotics.
18. Why are bacteria considered ubiquitous?
    They are found in all habitats including soil, water, air, and extreme environments.

Section C: Kingdom Protista and Fungi (Q19–Q28)

19. Describe the main characteristics of Kingdom Protista.
    Protists are unicellular eukaryotes with a true nucleus, mostly aquatic, and show varied modes of nutrition and locomotion.
20. Name and describe any two groups of Protista.
    Diatoms are photosynthetic protists with siliceous walls, while protozoans are heterotrophic and motile.
21. What is the ecological significance of diatoms?
    Diatoms form the base of aquatic food chains and contribute significantly to oxygen production.
22. Define Kingdom Fungi.
    Fungi are eukaryotic heterotrophs with chitinous cell walls, showing absorptive nutrition and spore-based reproduction.
23. Explain the structure of fungal body.
    The fungal body consists of thread-like hyphae forming a network called mycelium.
24. Describe the modes of reproduction in fungi.
    Fungi reproduce vegetatively, asexually by spores, and sexually through fusion of gametes.
25. Differentiate between fungi and plants.
    Fungi are heterotrophic with chitin cell walls, while plants are autotrophic with cellulose cell walls.
26. Name one useful fungus and its application.
    Penicillium is used in the production of the antibiotic penicillin.
27. What are deuteromycetes?
    Deuteromycetes are fungi in which sexual reproduction is not observed and are called imperfect fungi.
28. State the ecological role of fungi.
    Fungi act as decomposers, recycling nutrients in ecosystems.

Section D: Plantae, Animalia, Viruses, Viroids & Lichens (Q29–Q40)

29. State the general characteristics of Kingdom Plantae.
    Plantae are multicellular autotrophs with chlorophyll and cellulose cell walls, performing photosynthesis.
30. Why are plants called primary producers?
    They synthesise organic food from inorganic substances, forming the base of food chains.
31. Describe the general features of Kingdom Animalia.
    Animals are multicellular heterotrophs without cell walls and show complex organisation and mobility.
32. Why are animals called ingestive heterotrophs?
    They ingest solid food and digest it internally before absorption.
33. What are viruses?
    Viruses are acellular entities composed of nucleic acid and protein coat, acting as obligate parasites.
34. Why are viruses considered non-living outside host cells?
    They lack metabolism and reproductive ability outside living cells.
35. What are viroids?
    Viroids are infectious RNA molecules without protein coats that cause plant diseases.
36. Name a disease caused by viroids.
    Potato spindle tuber disease is caused by viroids.
37. What are lichens?
    Lichens are symbiotic associations between algae and fungi.
38. Explain the mutual relationship in lichens.
    Algae prepare food through photosynthesis, while fungi provide shelter and minerals.
39. Why are lichens considered pollution indicators?
    They are sensitive to air pollutants and fail to grow in polluted environments.
40. Why are comparative questions important in this chapter?
    The chapter involves classification, making comparisons essential for understanding similarities and differences among kingdoms.

Exam Relevance

✔ Strictly NCERT-aligned
✔ Ideal for 2–3 mark CBSE Class 11 questions
✔ Strong focus on comparisons and classification logic
✔ Suitable for school tests and annual examinations