Samacheer Class 7 Science - Basis of Classification

Binomial nomenclature is an universal system of naming organisms. As per this system, each organism has two names – the first is the Genus name and the second is the Species name.

Kingdom plantae
They are multicellular eukaryotes that can photosynthesize.
The cells have cell wall.
The cells can perform specialised functions like photosynthesis.
Eg. Ferns, cone bearing plants and flowering plants
Kingdom Animalia
They are multicellular, eukaryotic and heterotrophic animals.
The cells lack cell wall.
They cannot photosynthesize but animals move from place to place unlike plants.
Eg. Invertebrates and Vertebrates

This system of classification is more scientific and natural.
This system of classification clearly indicates the cellular organization, mode of nutrition, and characters for early evolution of life.

The five kingdom classification was proposed by R.H.Whittaker in 1969.
He classified the organisms into five kingdoms on the basis of characteristics like cell structure, mode of Nutrition, Source of Nutrition and body organization.

(i) Gaspard Bauhin jn 1623, introduced naming of organisms with two names which is known as Binomial nomenclature, and it was implemented by Carolus Linnaeas in 1753
(ii) Binomial nomenclature an universal system of naming organisms. As per this system, each organism has two names – the first is the Genusname and the second is the Speciesname.
(iii) Genus name begins with a capital letter and Species name begins with a small letter. Example The nomenclature for onion is Allium sativam. Genus name is Allium, species name is sativam.
(iv) Vernacular name is a local name that is familiar for a particular place. Binomial name is an universal name which never changes.
(v) Binomial nomenclature and classification helps scientists to identify any organisms and to place them at a particular hierarchy.

Invertebrates are animals without a backbone. The invertebrates have been classified into various phyla as follows:
S.No
Division
General Characters
1.
Phylum Protozoa
Eg. Amoeba, Euglena p
Microscopic unicellular, pseudopodia, flagella and cilia for locomotion, reproduce by fission or conjugation.
2.
Phylum Porifera
Eg. Leucosolenia, Sycon.
Multicellular organisms with holes in the body. Skeleton formed of spicules, asexual and sexual reproduction.
3.
Phylum Coelenterata Eg. Hydra, Jelly fish.
Multicellular organisms Diploblastic, sessile or free swimming, solitary or colonial, asexual and sexual reproduction
4.
Phylum Platyhelminthes Eg. Planaria, Liver fuke
Acoelomates, parasites inside the body of animals and human beings, mostly hermaphrodite (bisexual).
5.
Phylum Aschelminthes or Nematoda
Eg. Ascaris lumbricoides
Unsegmented body, mostly parasites in human beings and animals, causing diseases, asexual reproduction.
6.
Phylum Annelida Eg. Earthworm, Leech.
Triploblastic, segmented body, mostly hermaphrodite (bisexual and unisexual).
7.
Phylum Arthropoda Eg. Crab, Prawn
Segmented body, thick chitinous cuticle forming an exoskeleton, paired and jointed legs, unisexual exhibits sexual dimorphism.
8.
Phylum Mollusca Eg. Cuttle fish, Snail
Soft bodied, unsegmented, muscular head, foot and visceral mass, mantle, a calcareous shell, sexual reproduction.
9.
Phylum Echinodermata Eg. Starfsh, Sea – Urchin
Exclusively marine, spines and spicules over the body, water vascular system, tube feet, for feeding, respiration and locomotion sexual reproduction.

Kingdom Fungi comprises of unicellular to multicellular organisms which are heterotrophic in their mode of nutrition. They do not contain chlorophyll and cannot photosynthesize. Hence they show modes of Nutrition such as:
Saprophytic – Obtaining nutrition from dead matter Eg. Mucor
Parasitic – Obtaining nutrition from living organisms Eg. Cercospora
Symbiotic – Obtaining nutrition through a mutually beneficial relationship with another organism. Eg. Lichens