Biology 14.1 Classification

There are a vast number of organisms on Earth, so scientists need to name and sort them into groups.

Classification = organisation of living organisms into groups based on a number of accepted principles.

Concept of a species

A species = basic unit of classification. Members have certain things in common:

• Similar to one another but different from members of other species. - have similar genes so closely resemble each other physically and biochemically, have similar patterns of development and similiar immunological features - occupy the same ecological niche.
• Capable of breeding to produce living, fertile offspring - when a species reproduces sexually, any of the genes can be combined with another (belong to the same gene pool).

Namin species - binomial system

Scientists used to name organisms by describing their features e.g. blackbird.

However in different parts of the world same names were used for totally different species - difficult for scientists to be sure which organism was being referred to.

Binomial system = means of identifying organisms by two names:

• Based upon Latin or Greek names.
• Universal.
• First name = generic name (denotes genus to which organism belongs) - like a surname, shared by close relatives.
• Second name = specific name (denotes species) - like a first name but is never shared by other species within genus.

Rules for using binomial system:

• Names printed in italics or underlined if handwritten - shows that they're scientific names.
• First letter in generic name in capitals but no other letters.
• If specific name is not known it can be written as 'sp' e.g. Felix sp.

Naming of organisms is constnatly changing - classification of species is changing as knowledge of evolution, physical features, biochemistry and behaviour changes.

Grouping species together - the principles of classification

Organising species into managable groups allows better communication…