Diversity of Life:

Introduction to Biological Classification

By Lupupa K. Tembo

Kabwe Secondary School

Classification

• Classification is grouping things together on the basis of features they have in common

• It is a basic feature of all human activity

• Biological classification is known as Taxonomy

• Closely related to taxonomy is the way organisms are named and identified

What is taxonomy?

Taxonomy is the branch of biology concerned with the grouping and naming of organisms

Biologists who study this are called taxonomists

Importance of Classification

• Makes the study of living organisms easy

• Helps scientists to communicate information about living organisms clearly and unambiguously

• Helps to recognise how evolution may have given rise to diverse but related organisms

Who is Carolus Linnaeus?

• Carolus Linnaeus was a Swedish botanist

• Developed a 7-level (taxa) classification system based on similarities between organisms

The Seven Level System

KingdomPhylumClassOrderFamilyGenusSpecies

KingPhillipCameOverForGreenSoup

The Taxonomical groups

Kingdom largest taxon Phylum ClassOrderFamilyGenusSpecies smallest taxon

Linnaeus’ classification system has seven levels.

• Each level is included in the level above it.

• Levels get increasingly specific from kingdom to species.

How does it work?

There are 6 broad kingdomsEvery living thing that we know of fits into one of the six kingdomsEach level gets more specific as fewer organisms fit into any one group

• Physical similarities are not always the result of close relationships.

• Genetic similarities more accurately show evolutionary relationships.

KEY CONCEPT

Modern classification is based on evolutionary relationships.

The 3 Domains

PROKARYOTES

organisms with no nuclear membrane

organisms with a nuclear membrane

EUKARYOTES

The 6 Kingdoms

• Kingdoms are the largest division-all organisms are in one of the 6 kingdoms

• Animals • Plants• Fungi• Protists• Eubacteria• Archaebacteria

Prokaryotae

Binomial Nomenclature

Bi means twoNomen means nameA binomial nomenclature is a classification system using two names to identify an organism

Binomial Nomenclature

• Each type of organism is assigned two names:

• The first is the name of the genus (generic name) - starts with a capital letter

• The second is the name of the species (starts with a small letter)

• E.g Felis domestica (domestic cat)

• A genus includes one or more physically similar species.– Species in the same genus are thought to

be closely related.– Genus name is always capitalized.

• A species descriptor is the second part of a scientific name.– always lowercase– always follows genus

name; never written alone

Genus…• A genus consists of a group of closely related species

• A species consists of animals that can mate and produce fertile offspring

• Here is the classification for a Lion

• Kingdom: Animalia (animal kingdom)

• Phylum: Chordata (Vertebrates)• Class: Mammalia (mammals)• Order: Carnivora (carnivores)• Family: Felidae (cats)• Genus: Panthera• Species: Panthera leo

Other Examples of Classifications

Taxon Maize HumanKingdom Plantae AnimaliaPhylum Angiospermatophyta ChordataClass Monocotyledonae MammaliaOrder Graminales PrimatesFamily Graminaceae HominidaeGenus Zea HomoSpecies mays sapiens

FUNGI

FUNGI

Fungi sometimes look like plants, but they’re not!

Fungi can’t do photosynthesis, because they don’t have chloroplasts; they get their nutrients from the organic material they live in.

Decomposers, like mushrooms, feed on dead organic material.

Some fungi feed on living organisms, such as plants, animals and even other fungi. This causes diseases and infections in these organisms (like athlete’s foot and ringworm in humans).

Some fungi live as symbiotic partners with algae. The result: lichen (pronounced “like-n”). more lichen

Other differences from plants:• fungi don’t have roots, they have a mycelium.• fungi’s cell walls are made of chitin, not cellulose.

Kingdom Plantae• Green plants with chlorophyll and

other pigments• Photosynthetic• Multicellular with cell walls made

of cellulose• Large sap-filled vacuole• Plastids and other organelles• Reproduce asexually and sexually

Kingdom Protoctista (protists)

• Vary in size-from unicellular forms (e.g. Euglena, Amoeba, Paramecium and Plasmodium) to multicellular forms

• DNA enclosed in a membrane-bound nucleus

• Photosynthetic and Heterotrophic forms exist e.g. algae and protozoa respectively

• Reproduce asexually and sexually

Kingdom Animalia

• Multicellular organisms forming tissues and organs

• Motile in nature• Life processes controlled by nervous

system in most phyla• Heterotrophic • No chlorophyll, cell walls or sap-

vacuole

ANIMALS

Invertebrates (no backbone)

Vertebrates (backbone)

Kingdom Prokaryotae• Include bacteria and

cyanobacteria• Cytoplasm and DNA present• No true nucleus• No membrane-bound organelles• Simple methods of reproducing

e.g. fission• Several subphyla exist based on

biochemical characteristics• Found in soil, water, air, bodies of

other organisms

Dichotomous keys

• What is a dichotomous key?• A step-by-step guide to identify an

organism– Each step gives a choice of two

descriptions. – The descriptions have to be opposites

• Ex. Leaves round vs. leaves not round

• After each description, the key directs the user to another pair of descriptions or identifies the organism.

Quick Review

• What are the seven taxa or levels?

• Who designed the system?• What taxa are organisms named with?

Let us now try to use the dichotomous key provided to identify the insects shown

THANKYOU This concludes a brief review of

biological classification.