Chapter 9: Biodiversity and classification

9.1 Overview (ESGBP)

Introduction (ESGBQ)

So far learners have studied life from the molecular to the ecosystem level. This chapter examines the fantastic variety of life that exists on Earth, and introduces the systematic way of classifying organisms based on their evolutionary relationships. This sets the scene for the next chapter on the 'History of Life on Earth' where we will explore how this variety emerged.

There is enormous biodiversity on Earth, consisting of different ecosystems, containing a variety of species, which each have genetic differences.
South Africa is a 'hotspot' of diversity and has a large diversity of species endemic to the region.
Classification schemes are a way of categorising biodiversity based on common characteristics.
The history of classification began with Aristotle.
Currently, the most widely used classification system is the five-kingdom scheme consisting of the kingdoms: Animalia, Plantae, Fungi, Protista and Monera (or Bacteria)
In Science we name living organisms using a naming system called binomial nomenclature, which is written in the form: Genus, species
Based on cell structure, there are key differences between prokaryotes and eukaryotes.
The main groupings of living organisms are bacteria, protists, fungi, plants and animals.

'Biodiversity is the greatest treasure we have. Its diminishing is to be prevented at all costs'. — Thomas Eisner, US environmental scientist, who has made interesting findings into how organisms produce chemicals to fight off predation.

The diversity of life on Earth has fascinated scientists for generations. The earliest scientists attempted to understand life by categorising it according to a range of common traits. Over time these classification systems have changed based on the new evidence gathered. In this unit you will study the history of the system of classifying organisms, starting with Aristotle and progressing to the current five-kingdom system devised by Whittaker. You will also be introduced to the scientific convention of referring to organisms in Latin using two names - referred to as binomial nomenclature. It is important to try and draw connections between this section and the previous one in which you studied the plant and animal life common to each biome.

There is enormous biodiversity on Earth, consisting of different ecosystems, containing a variety of species, which each have genetic differences.
South Africa is a 'hotspot' of diversity and has a large diversity of species endemic to the region.
Classification schemes are a way of categorising biodiversity based on common characteristics.
The history of classification began with Aristotle.
Currently, the most widely used classification system is the five-kingdom scheme consisting of the kingdoms: Animalia, Plantae, Fungi, Protista and Monera (or Bacteria).
In Science we name living organisms using a naming system called binomial nomenclature, which is written in the form: Genus, species
Based on cell structure, there are key differences between prokaryotes and eukaryotes.
The main groupings of living organisms are bacteria, protists, fungi, plants and animals. Each of these categories of organisms have distinctive features that differentiate them.

End of chapter exercises

Table of Contents

9.2 Biodiversity