The Classification of Life

Classification of Life

Biology» The study of life

Taxonomy» Classification and naming of organisms

Classification of Life

Classification is the grouping of organisms according to their similarities and differences.

The main purpose of classification is to simplify the diversity among living organisms

Basis of Classification

1. comparative morphology (form and structure)

2. DNA

3. Cell structure

4. Biochemistry

5. Nutrition

History of Classification More than 2000 years ago

a Greek philosopher named Aristotle started classifying life.

Aristotle divided life into plants and animals.

The classification of plants was based on structure.

The basis for classification of animals was habitat.

Two major problems arose from his system:

numbers overlapping organisms

Carolus Linnaeus (1707-1778) developed a system of grouping organisms into hierarchical categories

He is considered to be the founder of modern taxonomy

Linnaeus based his classification system on structural similarities

Latin was the language for his new classification system

Purpose for using Latin: universal language dead/unchanging descriptive eliminate confusion

History of Classification

Linnaeus’ Seven Level Hierarchical System

1. Kingdom (the most general grouping)

2. Phylum

3. Class

4. Order

5. Family

6. Genus

7. Species

COMPREHENSION

QUESTION 1

Within his seven level system he gave every organism a scientific name using the genus and species descriptors. This naming system is called Binomial Nomenclature (two name system).

Linnaeus’ Seven Level Hierarchical System

Binomial Nomenclature

Genus is a noun and is always capitalized Species is an adjective and always lower

case Species is the lowest level of classification To be in the same species the organisms

have to be able to interbreed under natural conditions and produce fertile offspring.

Horse and donkey produce a mule (infertile) COMPREHENSION

QUESTION 2