What went wrong when the king rode under the arch?

It was too low and knocked off his crown

How does the chain of blame unfold in the poem?

Each accused person blames another, ending with the king's own changes

On what criteria did Whittaker base the Five Kingdom classification?

Cell structure, body organisation, mode of nutrition, mode of reproduction and phylogenetic relationships.

Name the four shapes of bacteria.

Coccus (spherical), bacillus (rod-shaped), vibrium (comma-shaped) and spirillum (spiral).

What are archaebacteria and where do they live?

They are bacteria with a distinct cell wall that survive harsh habitats; halophiles in salty areas, thermoacidophiles in hot springs and methanogens in marshy areas and the gut of ruminants.

How are viroids different from viruses?

Viroids are free RNA of low molecular weight lacking a protein coat, whereas viruses have genetic material enclosed in a protein capsid.

What do the terms phycobiont and mycobiont mean?

In a lichen the algal partner is the phycobiont (autotrophic) and the fungal partner is the mycobiont (heterotrophic).

What is the nature of cell walls in diatoms?

Diatom walls form two overlapping shells embedded with silica, making them indestructible and leaving deposits called diatomaceous earth.

Describe the four groups of protozoans.

Amoeboid protozoans move by pseudopodia; flagellated protozoans have flagella; ciliated protozoans use cilia and a gullet; sporozoans have an infectious spore-like stage, e.g. Plasmodium.

Prions are infectious agents made of abnormally folded protein, causing diseases such as mad cow disease (BSE) and Creutzfeldt-Jacob disease.

Why was the Two Kingdom system found inadequate?

It did not distinguish prokaryotes from eukaryotes, unicellular from multicellular, or photosynthetic from non-photosynthetic organisms.

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Chapter 2: Biological Classification — Class 11 Biology

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Chapter 2: Biological Classification

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The Five Kingdom classification was proposed by:

Summary

This chapter traces how classification systems evolved and presents Whittaker's Five Kingdom system. Aristotle gave an early scientific basis using simple morphology, and Linnaeus used a Two Kingdom system of Plantae and Animalia, which failed to separate prokaryotes from eukaryotes or autotrophs from heterotrophs. In 1969 R.H. Whittaker proposed five kingdoms: Monera, Protista, Fungi, Plantae and Animalia, using criteria such as cell structure, body organisation, mode of nutrition, reproduction and phylogenetic relationships. Kingdom Monera contains the prokaryotic bacteria, including archaebacteria of extreme habitats and eubacteria such as cyanobacteria and mycoplasma; bacteria show the widest metabolic diversity. Kingdom Protista groups single-celled eukaryotes: chrysophytes, dinoflagellates, euglenoids, slime moulds and protozoans. Kingdom Fungi covers heterotrophic organisms with chitinous walls and a body of hyphae forming a mycelium, classed into Phycomycetes, Ascomycetes, Basidiomycetes and Deuteromycetes. Kingdom Plantae includes chlorophyll-bearing plants and Kingdom Animalia the multicellular heterotrophs lacking cell walls. The chapter ends with acellular entities outside the five kingdoms: viruses (nucleoprotein particles with RNA or DNA), viroids (free infectious RNA), prions (misfolded proteins) and lichens (symbiotic associations of algae and fungi).

Evolution of classification systemsKingdom Monera: archaebacteria and eubacteriaKingdom ProtistaKingdom Fungi and its classesKingdoms Plantae and AnimaliaViruses, viroids, prions and lichens

Key terms

Five Kingdom classification

The system proposed by Whittaker (1969) dividing life into Monera, Protista, Fungi, Plantae and Animalia.

Monera

The kingdom of prokaryotic organisms (bacteria), including archaebacteria and eubacteria.

Protista

The kingdom of single-celled eukaryotes, primarily aquatic, with a well-defined nucleus.

Lichen

A symbiotic association between an alga (phycobiont) and a fungus (mycobiont).

Virus

A non-cellular, obligate parasite consisting of genetic material (RNA or DNA) within a protein coat (capsid).

Viroid

A free, low-molecular-weight infectious RNA lacking a protein coat, discovered by Diener.

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The system proposed by Whittaker (1969) dividing life into Monera, Protista, Fungi, Plantae and Animalia.

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Practice quiz · Biological Classification

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