Classification Basics

Question 1

What is classification?

Answer 1

• Classification is the act of arranging organisms into groups based on their similarities and differences.
• This makes it easier for scientists to identify and study them - Taxonomy is the study of classification.
• Until recently the most widely used system contained 7 groups ordered in a hierarchy - these are referred to as taxonomic groups.

Question 2

Taxonomic groups

Answer 2

• 7 groups are: Kingdom, Phylum, Class, Order, Family, Genus and Species.
• Kingdoms are the biggest and broadest taxonomic group and species is the smallest and most specific classification.
• Related or similar groups at one level are combined into more inclusive groups at the next higher level.

Question 3

Domain

Answer 3

• Based of more studies of genetic material, another level of classification has been added named domain.
• This level is at the top of the hierarchy.
• So similar organisms are first sorted into one of three very large domains.
• Animals, plants and fungi are in the Eukarya domain.
• The 3 domains are Archaea, Bacteria, and Eukarya.

Question 4

Why do scientists classify organisms?

Answer 4

• To identify species
• To predict characteristics
• To find evolutionary links: species in the same group probably share characteristics as they have evolved from a common ancestor.

Using a single classification system allows scientists worldwide to share their research.

Question 5

Species

Answer 5

• The smallest units of classification - each group contains only 1 type of organism.
• A species is defines as a group of organisms that are able to reproduce to produce fertile offspring.
• Animals are infertile is they have an odd number of chromosomes as meiosis and gamete production cannot take place correctly.

Question 6

Binomial system

Answer 6

• To ensure scientists over the world are discussing the same organism, we use a system named binomial nomenclature. This system helps avoid the confusion of common names.

They are given a scientific name consisting of 2 parts:
- First word indicates the genus - it’s called the generic name.
- Second word indicates the organism’s species - it’s called the specific name.
(names are written in italics or underlines; lowercase but genus uppercase)