Class 11 Biology Chapter 2 Biological Classification – Extra Questions with Answers

Chitin, the material forming a fungal cell wall, and T.O. Diener’s discovery of viroids are among the specific facts tested in this question set. Other questions cover the mycelium formed by fungal hyphae, the symbiotic partnership that makes up a lichen, and Whittaker’s five-kingdom classification.

Last Updated: September 23, 2026

Very Short Answer Questions (1 mark)

Q1. What is the cell wall of fungi made of?
Ans: Chitin.

Q2. Who discovered viroids?
Ans: T.O. Diener.

Q3. Name the network of fungal filaments.
Ans: Mycelium (made of hyphae).

Q4. What is a lichen?
Ans: A symbiotic association between an alga (or cyanobacterium) and a fungus.

Q5. In which kingdom are bacteria classified?
Ans: Monera.

Short Answer Questions (2–3 marks)

Q6. List the five kingdoms proposed by Whittaker with one defining feature of each.
Ans: Monera (prokaryotic), Protista (unicellular eukaryotic), Fungi (heterotrophic, chitin cell wall), Plantae (autotrophic, cellulose cell wall), Animalia (heterotrophic, no cell wall).

Q7. Differentiate between viruses and viroids.
Ans: Viruses have both nucleic acid and a protein coat; viroids consist only of free RNA without any protein coat, and are generally smaller than viruses.

Q8. What criteria did Whittaker use for the five kingdom classification?
Ans: Cell structure (prokaryotic/eukaryotic), body organization (thallus), mode of nutrition, mode of reproduction, and phylogenetic relationships.

Higher-Order Thinking / Application Questions

Q9. Explain why Protista is often described as a “bridge” or “link” kingdom connecting Monera, Fungi, Plantae, and Animalia, using specific examples of protistan groups that show characteristics of these other kingdoms.
Ans: Kingdom Protista contains a highly diverse array of unicellular eukaryotic organisms that show characteristics resembling multiple other kingdoms, which is why it is considered a transitional/connecting group. For example, euglenoids (like Euglena) have chloroplasts and can photosynthesize like plants, but also lack a cell wall and can be heterotrophic (ingesting food) like animals when light is unavailable, showing plant-animal intermediate features. Slime moulds show characteristics of fungi in their reproductive/spore-forming stage, but move like amoeba (animal-like) during their feeding (plasmodial) stage. Chrysophytes and dinoflagellates (photosynthetic, plant-like) sit alongside protozoans (heterotrophic, animal-like) within the same kingdom. This diversity of features spanning autotrophic, heterotrophic, and even fungus-like life cycles within a single kingdom is why Protista is regarded as evolutionarily and functionally transitional, bridging simpler prokaryotic Monera and the more specialized multicellular kingdoms (Fungi, Plantae, Animalia).

Q10. Explain why viruses are considered to exist at the border between living and non-living things, discussing both the “living” and “non-living” characteristics they exhibit.
Ans: Viruses exhibit certain properties associated with living organisms: they contain genetic material (DNA or RNA), can replicate (reproduce), undergo mutation, and can evolve over time — all hallmark features of life. However, outside a host cell, viruses are completely inert: they show no metabolism of their own (no independent respiration, growth, or biochemical activity), cannot reproduce independently, and can even be crystallized like a chemical compound (as demonstrated historically with the tobacco mosaic virus), which is characteristic of non-living matter. It is only upon infecting a living host cell that a virus “comes alive” in a functional sense, hijacking the host’s cellular machinery (ribosomes, enzymes, energy) to replicate its genetic material and produce new virus particles. This dual nature — inert and crystallizable outside a cell, yet capable of genetic replication and evolution inside a host — is why viruses occupy a unique, ambiguous position at the boundary between living and non-living entities, and are excluded from the five kingdom classification system, which is based on cellular life.

Frequently Asked Questions

How would you classify a mushroom using the five kingdom system?
A mushroom is placed in kingdom Fungi, since it is a eukaryotic, non green, heterotrophic organism that absorbs nutrients rather than making or ingesting food.

Why would you place blue-green algae in kingdom Monera rather than Plantae despite the name suggesting algae?
Blue-green algae are prokaryotic, lacking a defined nucleus and membrane bound organelles, which places them in Monera rather than the eukaryotic kingdom Plantae.

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.