Maarg Manthan · Topic 6.11

Plant and Animal Kingdom Classification

Environment & Ecology › Biodiversity Basics and Classification · Topic 6.11

Classification groups organisms by shared features and evolutionary relationships. Carl Linnaeus began modern taxonomy with binomial nomenclature, giving each species a two-part Latin name (genus and species). The ranks in order are domain, kingdom, phylum (division in plants), class, order, family, genus and species. R.H. Whittaker's five-kingdom system (1969) has Monera, Protista, Fungi, Plantae and Animalia, and Carl Woese's three-domain system (1990) places life in Bacteria, Archaea and Eukarya. Plants are grouped into algae, bryophytes, pteridophytes, gymnosperms and angiosperms, the last divided into monocots and dicots. Animals are grouped into non-chordates (Porifera, Cnidaria, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata) and chordates, with subphyla Urochordata, Cephalochordata and Vertebrata, whose classes are Cyclostomata, Pisces, Amphibia, Reptilia, Aves and Mammalia.

5 min read · UPSC Prelims · Environment & Ecology · Biodiversity Basics and Classification

At a Glance

Naming system Binomial, Linnaeus
Five kingdoms Whittaker, 1969
Three domains Woese, 1990
Plant groups Five
Vertebrate classes Six
Exam link UPSC Prelims, Environment & Ecology: Biodiversity Basics and Classification

Where Does It Fit?

This topic follows biopiracy. It gives the basic vocabulary of biological classification that is needed for the species-level topics, such as the Red List and protected species, in later macros. Previous topic: Biopiracy. Next topic: Marine Mammals, Egg-Laying Mammals and Marsupials.

How Are Plants and Animals Classified?

Group	Key features and examples
Algae	Thallophytes with chlorophyll; no roots or stems; aquatic. Green, brown and red algae. Spirogyra, Sargassum
Bryophytes	Amphibians of the plant kingdom: need water to reproduce; no vascular tissue. Mosses, liverworts like Funaria and Marchantia
Pteridophytes	First vascular plants; no seeds; spores. Ferns, horsetails, Selaginella
Gymnosperms	Naked seeds; cones; no fruits. Pine, cedar, cycas, deodar, Ginkgo
Angiosperms	Flowering plants; seeds in fruits. Monocots (one cotyledon, parallel veins: wheat, banana, palm) and dicots (two cotyledons, net veins: pea, mango)
Porifera	Sponges; pores; no organs. Sycon
Cnidaria	Stinging cells; radial symmetry. Hydra, jellyfish, corals, sea anemone

What Are the Other Animal Groups and Naming Rules?

Platyhelminthes: flatworms, e.g., tapeworm, liver fluke
Aschelminthes (Nematoda): roundworms, e.g., Ascaris
Annelida: segmented worms, e.g., earthworm, leech
Arthropoda: largest phylum; jointed legs; insects, spiders, crabs, millipedes
Mollusca: soft body; shell; snail, octopus, squid
Echinodermata: spiny skin; starfish, sea urchin; water vascular system
Chordata: notochord, dorsal nerve cord and pharyngeal gill slits; vertebrates
Vertebrate classes: Cyclostomata (lampreys), Pisces (fish), Amphibia (frogs), Reptilia (snakes), Aves (birds), Mammalia (humans)

What Else Should You Remember?

Binomial nomenclature: genus name first with capital, species name in lower case, both in italics, like Mangifera indica
Linnaeus: Systema Naturae, 1735, and Species Plantarum, 1753
Taxon: any group at any rank
Taxonomy: science of naming and classifying
Systematics: study of diversity and evolutionary relationships
Whittaker’s criteria: cell structure, body organisation, mode of nutrition, reproduction and phylogeny
Monera: prokaryotes; bacteria and cyanobacteria
Protista: unicellular eukaryotes; Amoeba, Paramecium, diatoms
Fungi: heterotrophic, with chitin cell wall; yeast, mushrooms
Plantae: multicellular autotrophs with cellulose walls
Animalia: multicellular heterotrophs without cell walls
Viruses: not in the kingdoms; non-cellular
Lichens: symbiosis of algae or cyanobacteria and fungi; pollution indicators
Archaea: extremophile prokaryotes in hot springs, salt lakes and guts
Phylogeny: evolutionary history
Cladistics: classification by branching evolutionary lines
Alternation of generations: plants alternate between sporophyte and gametophyte
Dominant phase: gametophyte in bryophytes, sporophyte in pteridophytes and seed plants
Hemichordata: acorn worms
Cartilaginous fish: sharks and rays; skeleton of cartilage
Bony fish: rohu, catla and others with a swim bladder
Mammal traits: mammary glands, hair, three middle ear bones, diaphragm
Link to previous: see Biopiracy
Link to next: see Marine Mammals, Egg-Laying Mammals and Marsupials
Link to red list: see IUCN Red List and Its Classification Scheme
Caution: many textbooks revise names; use the NCERT scheme for exam tables
Exam hint: learn kingdoms with one example each and plant groups with a spore or seed trait
Algae groups: green algae (Chlorophyceae), brown algae (Phaeophyceae) and red algae (Rhodophyceae) differ in pigments: chlorophyll a and b, fucoxanthin and phycoerythrin respectively
Algae uses: Laminaria and Sargassum give algin, Gelidium and Gracilaria give agar, Chlorella is a protein-rich food and space research organism
Bryophyte role: mosses form peat, prevent soil erosion and are early colonisers of bare rock in ecological succession
Pteridophyte role: ferns are ornamental, and Azolla is a nitrogen-fixing biofertiliser used in rice fields
Gymnosperm examples: the redwood Sequoia is among the tallest trees, and Cycas and Pinus are common in Indian botany texts
Angiosperm cell division: double fertilisation is a unique feature, forming zygote and endosperm
Insects: class Insecta has three pairs of legs, a body of head, thorax and abdomen, and includes the largest number of species on Earth
Reptiles and birds: reptiles are cold-blooded with scales, birds are warm-blooded with feathers and a four-chambered heart
Amphibians: live both on land and in water and breathe through skin, lungs and gills at different stages; frogs, toads and salamanders
Mammal groups: monotremes, marsupials and placentals are detailed in the next topic
Lichen role: pollution indicators and primary colonisers; Parmelia is a common genus
Number of species: about 1.7 to 2 million described, of which insects are over half

Why Does It Matter for the Exam?

Naming: binomial
Kingdoms: five
Plants: five groups
Current affairs link: new species discoveries
Common errors: calling viruses a kingdom or confusing monocot and dicot traits

As an analytical point, classification is the shared language of biology, and it underlies conservation lists and legal schedules. New molecular methods are revising old groupings, so names change as relationships become clearer.

Why Is This Topic Important?

System Binomial
Kingdoms Five
Groups Plant and animal

What Came Next?

The next topic covers marine mammals, egg-laying mammals and marsupials. Next topic: Marine Mammals, Egg-Laying Mammals and Marsupials.

Key People and Terms

Taxon Any classification group
Binomial nomenclature Two-part name
Monocot Single seed leaf
Dicot Two seed leaves
Notochord Rod in chordates
Kingdom High-level group

Exam Corner

Points to Remember

Binomial by Linnaeus.
Five kingdoms by Whittaker.
Gymnosperms have naked seeds.
Arthropoda is the largest phylum.
Six vertebrate classes.

Do Not Confuse With

Monocot and dicot One seed leaf, parallel veins versus two, net veins
Bryophyte and pteridophyte Non-vascular versus vascular
Gymnosperm and angiosperm Naked seeds versus seeds in fruit

Memory Hook

Algae, Bryo, Ptero, Gymno, Angio: from pond scum to flowering crown.

Mains Angle

Questions ask for groups and examples. These points help.

Systems Linnaeus, Whittaker
Plants Five
Animals Phyla

A Question You May Face

An original practice question, not a past paper question.

“Explain the five-kingdom system of classification and describe the major groups of plants and animals with examples.”

How to Answer

Naming Binomial.
Kingdoms Five.
Plants Groups.
Animals Phyla.

GS Relevance

Prelims: Linnaeus, Whittaker, plant groups, animal phyla, vertebrate classes. GS Paper 3: biodiversity basics.

Frequently Asked Questions

What is binomial nomenclature?

Binomial nomenclature is the system of giving every species a two-part Latin name, consisting of the genus and the species, such as Panthera tigris for the tiger. It was introduced by Carl Linnaeus, and the name is written in italics, with the genus capitalised and the species in lower case.

What are the five kingdoms of life?

R.H. Whittaker proposed five kingdoms in 1969: Monera, comprising prokaryotes such as bacteria, Protista, comprising unicellular eukaryotes, Fungi, Plantae and Animalia. They are based on cell structure, body organisation, mode of nutrition, reproduction and evolutionary relationships. Viruses are not included.

What is the difference between gymnosperms and angiosperms?

Gymnosperms are seed plants whose seeds are not enclosed in a fruit, such as pine, deodar and cycas, which bear cones. Angiosperms are flowering plants whose seeds develop inside fruits formed from the ovary, such as mango and wheat. Angiosperms are the largest and most diverse plant group.

What are the characteristics of chordates?

Chordates have a notochord, a dorsal hollow nerve cord and pharyngeal gill slits at some stage of life, along with a post-anal tail. Vertebrates, the largest group, replace the notochord with a backbone, and are divided into fish, amphibians, reptiles, birds and mammals, plus the jawless cyclostomes.

Which is the largest phylum of animals?

Arthropoda is the largest phylum of the animal kingdom, accounting for more than two thirds of all known animal species. It includes insects, spiders, crustaceans like crabs and prawns, centipedes and millipedes, and its members have jointed legs, a segmented body and a hard exoskeleton made of chitin.

PYQ Practice — Statement Analysis

1 Carl Linnaeus introduced binomial nomenclature.

True

Two-part Latin names.

2 Gymnosperms bear seeds enclosed in fruits.

False

Their seeds are naked.

3 Arthropoda is the largest phylum of animals.