GENERAL PRINCIPLES OF CLASSIFICATION
- Classification is the science that puts organisms into distinct groups to make their study easy and systematic.
- Modern scientific classification is based on structure and functions.
- Organisms with similar anatomical and morphological characteristics are placed in one group while those with different structures are grouped separately.
- Modern studies in genetics and cell biochemistry are used to give additional help in classifying organisms.
- There are seven major taxonomic groups.
- The kingdom is the largest group.
- Others are phylum (division for plants) class, order, family, genus and species, the smallest.
- Living organisms are named using Latin or Latinised names.
- Every organism has two names.
- This double naming is called binomial nomenclature.
- This system of naming was devised by Carolus Linnaeus in the 18th Century.
- The first name is the generic name – the name of the genus.
- The second name is the name of the species.
- The generic name starts with a capital letter while that of the species starts with a small letter.
- The names are written in italics or are underlined in manuscripts.
Bean =Phaseolus vulgaris.
- Phaseolus is the generic name,
- Vulgaris is specific name. Dog = Canis familiaris.
- Canis is the generic name, familiaris the specific name.
General Characteristics of Kingdoms Organisms are classified into five kingdoms.
Viruses do not fit neatly into any of the above kingdoms.
- They are simple and not cellular.
- They are metabolically inactive outside the host cell.
- Most of them can be crystallised like chemical molecules.
- Therefore they do not exhibit the characteristics of living organisms.