Why Brinjal Has a Hundred Local Names but Only One Scientific Name
Understand biodiversity and why classification is needed, write binomial names correctly using the rules of nomenclature, place organisms in the taxonomic hierarchy from species to kingdom, and tell taxonomy from systematics with the biological species concept.
How do biologists keep track of so many living things?
Walk through a village in India and you will meet neem trees, sparrows, earthworms, mushrooms and countless microbes. Across the planet, the variety of life is staggering — and it has to be organised before anyone can study it.
Biologists do this with names that mean the same thing everywhere and groups nested inside groups, from the smallest unit to the largest.
This chapter covers biodiversity and the need for classification, binomial nomenclature, the taxonomic hierarchy, and taxonomy, systematics and the species concept.
Biologists do this with names that mean the same thing everywhere and groups nested inside groups, from the smallest unit to the largest.
This chapter covers biodiversity and the need for classification, binomial nomenclature, the taxonomic hierarchy, and taxonomy, systematics and the species concept.
What is biodiversity, and why is classification necessary?
**Biodiversity is the variety of living organisms on Earth; biologists have described roughly to million species so far, and with so many, classification into groups is the only practical way to identify, name and study them.
Why classify:
- Identification becomes quicker — knowing the group narrows down what an organism is
- Study becomes manageable — one representative can teach a lot about its whole group
- Relationships between organisms become clear
- New species can be placed alongside their closest relatives
How it works. Organisms are grouped by shared characters — for example, all animals with a backbone form one group, all plants that bear flowers another.
Worked example. A bat, a crow and a butterfly all fly, but a bat has hair and feeds its young on milk, like a cow, while a crow has feathers and lays eggs. Grouping by these deeper characters places the bat with mammals and the crow with birds, not together as "flying animals".
An everyday example. A kirana shop sorts its stock into grains, spices, oils and snacks, so any item can be found quickly — classification does the same for living things.
The substance. The described species are only part of the total**, since many organisms, especially insects and microbes, remain undiscovered.
Why classify:
- Identification becomes quicker — knowing the group narrows down what an organism is
- Study becomes manageable — one representative can teach a lot about its whole group
- Relationships between organisms become clear
- New species can be placed alongside their closest relatives
How it works. Organisms are grouped by shared characters — for example, all animals with a backbone form one group, all plants that bear flowers another.
Worked example. A bat, a crow and a butterfly all fly, but a bat has hair and feeds its young on milk, like a cow, while a crow has feathers and lays eggs. Grouping by these deeper characters places the bat with mammals and the crow with birds, not together as "flying animals".
An everyday example. A kirana shop sorts its stock into grains, spices, oils and snacks, so any item can be found quickly — classification does the same for living things.
The substance. The described species are only part of the total**, since many organisms, especially insects and microbes, remain undiscovered.
How do you write and correct binomial names using the rules of nomenclature?
Every organism gets a two-part scientific name — genus followed by specific epithet — written in Latin or Latinised form, printed in italics or underlined separately when handwritten, with the genus starting with a capital letter and the epithet with a small letter, often followed by the author's name in abbreviated form.
The rules:
- Two words: genus first, then specific epithet — Mangifera indica for mango
- Latinised regardless of the organism's origin
- Italics when printed; each word underlined separately when handwritten
- Capital first letter for the genus; small first letter for the epithet
- Author citation in abbreviated, non-italic form after the name — Mangifera indica Linn.
Worked examples — correct names. Homo sapiens (human), Panthera tigris (tiger), Oryza sativa (rice), Triticum aestivum (wheat), Azadirachta indica (neem), Solanum melongena (brinjal), Solanum tuberosum (potato).
Worked example — correcting mistakes.
- "mangifera Indica" should be Mangifera indica
- "Homo Sapiens" should be Homo sapiens
An everyday example. Brinjal is baingan in Hindi and vangi in Marathi, but scientists in every country call it Solanum melongena.
The substance. The specific epithet alone is meaningless — "indica" appears in both Mangifera indica and Azadirachta indica.
The rules:
- Two words: genus first, then specific epithet — Mangifera indica for mango
- Latinised regardless of the organism's origin
- Italics when printed; each word underlined separately when handwritten
- Capital first letter for the genus; small first letter for the epithet
- Author citation in abbreviated, non-italic form after the name — Mangifera indica Linn.
Worked examples — correct names. Homo sapiens (human), Panthera tigris (tiger), Oryza sativa (rice), Triticum aestivum (wheat), Azadirachta indica (neem), Solanum melongena (brinjal), Solanum tuberosum (potato).
Worked example — correcting mistakes.
- "mangifera Indica" should be Mangifera indica
- "Homo Sapiens" should be Homo sapiens
An everyday example. Brinjal is baingan in Hindi and vangi in Marathi, but scientists in every country call it Solanum melongena.
The substance. The specific epithet alone is meaningless — "indica" appears in both Mangifera indica and Azadirachta indica.
How do you place an organism in the taxonomic hierarchy, and why do shared characters decrease at higher ranks?
The taxonomic hierarchy arranges categories from species, the lowest, through genus, family, order, class and phylum (or division for plants) up to kingdom, and the higher the rank, the more organisms it holds and the fewer characters they all share.
Worked example 1 — mango.
- Species: indica
- Genus: Mangifera
- Family: Anacardiaceae
- Order: Sapindales
- Class: Dicotyledonae
- Division: Angiospermae
- Kingdom: Plantae
Worked example 2 — human. Species sapiens, genus Homo, family Hominidae, order Primata, class Mammalia, phylum Chordata, kingdom Animalia.
Worked example 3 — sharing characters. The lion (Panthera leo) and tiger (Panthera tigris) share a genus, so they are very similar. A cat is in the same family, Felidae, but a different genus, so it shares fewer features. A dog is in the same order, Carnivora, but a different family — fewer still.
An everyday example. A full postal address narrows from country to state, city, locality and house — the taxonomic hierarchy works in the same nested way, in reverse.
The substance. Each rank is a category, and a group placed at that rank is a taxon — Mammalia is a taxon at the rank of class.
Worked example 1 — mango.
- Species: indica
- Genus: Mangifera
- Family: Anacardiaceae
- Order: Sapindales
- Class: Dicotyledonae
- Division: Angiospermae
- Kingdom: Plantae
Worked example 2 — human. Species sapiens, genus Homo, family Hominidae, order Primata, class Mammalia, phylum Chordata, kingdom Animalia.
Worked example 3 — sharing characters. The lion (Panthera leo) and tiger (Panthera tigris) share a genus, so they are very similar. A cat is in the same family, Felidae, but a different genus, so it shares fewer features. A dog is in the same order, Carnivora, but a different family — fewer still.
An everyday example. A full postal address narrows from country to state, city, locality and house — the taxonomic hierarchy works in the same nested way, in reverse.
The substance. Each rank is a category, and a group placed at that rank is a taxon — Mammalia is a taxon at the rank of class.
How is taxonomy different from systematics, and what is the biological concept of species?
Taxonomy covers characterisation, identification, naming and classification of organisms, while systematics is broader, also studying their diversity and evolutionary relationships; a species, in the biological concept, is a group of organisms that can interbreed in nature to produce fertile offspring.
Taxonomy's basic steps:
- Characterisation — describing features
- Identification — deciding what the organism is
- Nomenclature — giving the correct scientific name
- Classification — placing it in groups
Systematics adds phylogeny — how groups are related through common ancestry.
Species criteria.
- Reproductive: individuals interbreed and produce fertile young
- Morphological: individuals share fundamental similarities in structure
Worked example — the mule. A horse and a donkey can mate, but their offspring, the mule, is sterile. So the horse and donkey are separate species.
Worked example — dogs. A Labrador and an Indian street dog look very different but interbreed and produce fertile puppies, so they belong to one species.
An everyday example. Street dogs of every size and colour in an Indian town are all one species, however different they look.
The substance. Appearance can mislead — males and females, or young and adults, of one species may look very different.
Taxonomy's basic steps:
- Characterisation — describing features
- Identification — deciding what the organism is
- Nomenclature — giving the correct scientific name
- Classification — placing it in groups
Systematics adds phylogeny — how groups are related through common ancestry.
Species criteria.
- Reproductive: individuals interbreed and produce fertile young
- Morphological: individuals share fundamental similarities in structure
Worked example — the mule. A horse and a donkey can mate, but their offspring, the mule, is sterile. So the horse and donkey are separate species.
Worked example — dogs. A Labrador and an Indian street dog look very different but interbreed and produce fertile puppies, so they belong to one species.
An everyday example. Street dogs of every size and colour in an Indian town are all one species, however different they look.
The substance. Appearance can mislead — males and females, or young and adults, of one species may look very different.
Exam tip
What earns full marks on the living world chapter?
When writing a scientific name in the exam, underline genus and epithet separately and check the capital letters before moving on.
- Biodiversity: about to million species described
- Binomial rules: Latinised, genus capitalised, epithet small, italics or separate underlines, author citation
- Hierarchy: species, genus, family, order, class, phylum or division, kingdom
- Characters shared: most at species, fewest at kingdom
- Species concept: interbreeding with fertile offspring
The trap. Writing "Mangifera Indica" with a capital I. The specific epithet always starts with a small letter.
- Biodiversity: about to million species described
- Binomial rules: Latinised, genus capitalised, epithet small, italics or separate underlines, author citation
- Hierarchy: species, genus, family, order, class, phylum or division, kingdom
- Characters shared: most at species, fewest at kingdom
- Species concept: interbreeding with fertile offspring
The trap. Writing "Mangifera Indica" with a capital I. The specific epithet always starts with a small letter.
Did you know
Why do scientists still use Latin to name living things?
Everyday languages change constantly — words shift meaning and new ones appear. Latin is no longer anyone's first language, so its words stay fixed, which makes it ideal for names that must never change.
Latinised names also give a neutral common ground. A researcher in Kerala, one in Kenya and one in Canada may each call a plant something different at home, but Azadirachta indica means neem to all of them.
The endings even carry clues: plant family names usually end in -aceae, as in Anacardiaceae and Solanaceae, so the rank of a name can often be spotted at a glance.
Latinised names also give a neutral common ground. A researcher in Kerala, one in Kenya and one in Canada may each call a plant something different at home, but Azadirachta indica means neem to all of them.
The endings even carry clues: plant family names usually end in -aceae, as in Anacardiaceae and Solanaceae, so the rank of a name can often be spotted at a glance.
Exam relevance
How is The Living World tested in NEET?
The Living World opens the Diversity in the Living World unit of NEET Biology, and its vocabulary is used in every classification chapter that follows.
What gets asked. Rules of binomial nomenclature, including spotting a wrongly written name, the correct order of taxonomic categories, matching organisms such as mango, wheat, housefly and human with their family, order or class, and statement questions on taxonomy, systematics and the species concept. These categories are applied straight away in Biological Classification, Plant Kingdom and Animal Kingdom.
Question types. Statement-based questions, match-the-column lists and assertion-reason questions.
The trap that costs marks. Mixing up the positions of order and family in the hierarchy.
What gets asked. Rules of binomial nomenclature, including spotting a wrongly written name, the correct order of taxonomic categories, matching organisms such as mango, wheat, housefly and human with their family, order or class, and statement questions on taxonomy, systematics and the species concept. These categories are applied straight away in Biological Classification, Plant Kingdom and Animal Kingdom.
Question types. Statement-based questions, match-the-column lists and assertion-reason questions.
The trap that costs marks. Mixing up the positions of order and family in the hierarchy.
Key takeaways
What must you be able to do from this part?
- Biodiversity: roughly to million described species; classification makes them identifiable
- Binomial nomenclature: Mangifera indica Linn. — genus capitalised, epithet small, italics or separate underlining
- Hierarchy: mango is Mangifera, Anacardiaceae, Sapindales, Dicotyledonae, Angiospermae, Plantae; lion and tiger share the genus Panthera
- Taxonomy and species: systematics adds evolutionary relationships; a sterile mule shows horse and donkey are separate species
Arrange these categories for wheat in the right order — Poales, Plantae, Triticum, Poaceae, Angiospermae, Monocotyledonae — and write its full binomial name correctly.
- Binomial nomenclature: Mangifera indica Linn. — genus capitalised, epithet small, italics or separate underlining
- Hierarchy: mango is Mangifera, Anacardiaceae, Sapindales, Dicotyledonae, Angiospermae, Plantae; lion and tiger share the genus Panthera
- Taxonomy and species: systematics adds evolutionary relationships; a sterile mule shows horse and donkey are separate species
Arrange these categories for wheat in the right order — Poales, Plantae, Triticum, Poaceae, Angiospermae, Monocotyledonae — and write its full binomial name correctly.