Lesson 8 of 8 · 11 min

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Whole chapter revision, naming to hierarchy
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Must-know facts

18 facts

1Known and described species number 1.7 to 1.8 million, and new ones are still being found.
2Plant names follow ICBN; animal names follow ICZN.
3Binomial nomenclature was given by Carolus Linnaeus: generic name + specific epithet.
4Genus starts with a capital letter, specific epithet with a small letter: Mangifera indica.
5Printed names are italic; handwritten names have each word underlined separately.
6Mangifera indica Linn.: 'Linn.' is the abbreviated author, showing Linnaeus first described it.
7Four processes basic to taxonomy: characterisation, identification, classification, nomenclature.
8Systematics comes from Latin 'systema'; Linnaeus wrote Systema Naturae; systematics considers evolutionary relationships.
9Order of categories upward: species, genus, family, order, class, phylum (division in plants), kingdom.
10Species is the lowest category; kingdom is the highest.
11Going up the hierarchy, the number of shared characters decreases.
12Solanum, Petunia and Datura are in Solanaceae; Solanaceae and Convolvulaceae are in order Polymoniales.
13Panthera and Felis are in family Felidae; Felidae and Canidae are in order Carnivora.
14Order Primata and order Carnivora are both in class Mammalia.
15Chordata is defined by a notochord and a dorsal hollow neural system.
16Housefly: Muscidae, Diptera, Insecta, Arthropoda.
17Man: Hominidae, Primata, Mammalia, Chordata.
18Mango: Anacardiaceae, Sapindales, Dicotyledonae, Angiospermae; wheat: Poaceae, Poales, Monocotyledonae, Angiospermae.

Common traps

Where marks are lost

Writing the epithet with a capital letter, as in Mangifera Indica.

Only the genus is capitalised. The epithet always begins with a small letter, even when it comes from a place name.

Underlining a handwritten binomial with one continuous line.

The two words are underlined separately, one line under each.

Thinking members of a kingdom share more characters than members of a genus.

Shared characters decrease going up. Species members share the most; kingdom members share the fewest.

Using 'phylum' for plants.

For plants the equivalent category is division, as in division Angiospermae for mango and wheat.

Writing the order of man as Primates.

NCERT's table gives order Primata for man, in class Mammalia.

Placing Solanaceae in the order Sapindales or Poales.

Solanaceae and Convolvulaceae are in Polymoniales. Sapindales is mango's order; Poales is wheat's.

Treating taxonomic groups as mere groups of look-alikes.

NCERT stresses that taxonomic categories are distinct biological entities, not just morphological aggregates.

Putting cats in the genus Panthera.

Cats are in the genus Felis. Panthera (lion, tiger, leopard) and Felis share the family Felidae.

Key terms

17 terms

Biodiversity: The number and kinds of organisms present on earth.
Species: A group of individuals with fundamental similarities, set apart from close relatives by distinct morphological differences; the lowest taxonomic category.
Identification: Describing an organism correctly so that we know which organism a name refers to.
Nomenclature: Standardised naming, so that an organism has the same name all over the world.
ICBN: International Code for Botanical Nomenclature, the rules for naming plants.
ICZN: International Code of Zoological Nomenclature, the rules for naming animals.
Binomial nomenclature: Naming each organism with two words, the generic name and the specific epithet, as introduced by Linnaeus.
Specific epithet: The second word of a scientific name, marking the particular species within the genus.
Classification: Grouping into convenient categories on the basis of easily observable characters.
Taxon: A group of organisms at any rank of classification, such as dogs, mammals or animals; plural taxa.
Taxonomy: Classifying organisms into taxa on the basis of their characteristics.
Systematics: The study of the diversity of organisms and the relationships among them, including evolutionary ones.
Taxonomic hierarchy: All the taxonomic categories arranged in order of rank, from species to kingdom.
Genus: A group of closely related species that share more characters than they do with species of other genera.
Family: A group of related genera, characterised in plants on vegetative and reproductive features.
Order: An assemblage of families that show a few similar characters.
Division: The plant category equivalent to a phylum, grouping related classes.

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