Essential NEET Facts — The Living World — Summary

Defining feature of life = Metabolism (sum of all anabolic + catabolic reactions). Growth and reproduction are NOT the defining features — they have notable exceptions.
Growth exceptions: Non-living crystals grow by accumulation. This is the key reason growth cannot define life.
Reproduction exceptions: Mules (horse x donkey hybrids = sterile), worker bees (sterile females), infertile humans — all alive but cannot reproduce.
Metabolism criterion: The only feature present in all living organisms and in no non-living entity. Even isolated enzyme reactions in a test tube qualify as metabolic.
Consciousness is proposed as defining property — ability to sense and respond to environment; present even in unicellular organisms and plants.
Taxonomy coined by A.P. de Candolle. Encompasses: identification + nomenclature + classification.
Systematics = taxonomy + evolutionary/phylogenetic relationships. Derived from Latin systema.
Taxonomic hierarchy (most to least inclusive): Kingdom → Phylum/Division → Class → Order → Family → Genus → Species.
Phylum = animals; Division = plants.
Taxon = any unit/group at any taxonomic rank.
Moving from Species to Kingdom: number of common characteristics decreases; number of organisms increases.
Binomial nomenclature established by Carolus Linnaeus in Systema Naturae.
Scientific name = Genus (capital first letter) + specific epithet (all lowercase).
In print: italicised (Homo sapiens). Handwritten: each word underlined separately.
Latin or Latinised names. Author name abbreviated after species (Mangifera indica Linn.).
Species = basic unit of classification = group that interbreeds to produce fertile offspring.
Kingdom = most inclusive taxonomic category.
Herbarium: dried/pressed/mounted plant specimens with labels (date, place, collector).
Botanical Garden: living plant collection (Kew, England; Indian Botanical Garden, Howrah).
Dichotomous key: paired contrasting characters (couplets) used for identification.
Flora: describes plant species in a specific geographical area.
Monograph: detailed study of a single taxon $\frac{one genus}{family}$ .
Type specimen: reference specimen in herbarium/museum serving as nomenclatural standard.
Housefly classification: Diptera (order), Muscidae (family), Musca domestica.
Wheat classification: Poales (order), Poaceae (family), Triticum aestivum.