Diversity of living things
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DIVERSITY OF LIVING THINGS. Organization of Organisms. Diversity. The vast diversity of living things is astounding! Biologists study differences between organisms in order to classify them Diversity within species is important to the species survival

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Diversity of living things


Organization of Organisms



  • The vast diversity of living things is astounding!

  • Biologists study differences between organisms in order to classify them

  • Diversity within species is important to the species survival

  • Humans depend on the Earth’s biodiversity for food and products



  • Biodiversity is the variability of all living organisms -- including animal and plant species -- of the genes of all these organisms

  • Biodiversity makes up the structure of the ecosystems and habitats that support essential living resources, including wildlife, fisheries and forests.

  • Helps provide for basic human needs such as food, shelter, and medicine.

Why do scientists classify organisms

Why do Scientists Classify Organisms?

  • Is 30-100 million kinds of organisms on Earth!

  • Need to keep them organized

  • Classification: the process of grouping things based on their similarities

Classification of living organisms

Classification of Living Organisms

  • Biologists use taxonomy and phylogeny to organize organisms

  • Sexual reproduction maintains genetic variability which provides a greater diversity of genotypes that can survive environmental changes; in turn ensuring a species survival!

Diversity of species

Diversity of Species



  • About 2300 years ago Aristotle first started to group animals according to their habitat

  • Aristotle observed animals’ appearance, behaviour, types of movement and observed similarities and differences

  • He used the differences to divide them into smaller subgroups

  • In 1665 when the microscope was discovered, many varieties of microscopic organisms were discovered



  • Now, there were lots of organisms and the need for an effective classification system became evident

  • John Ray in the 17th century was first to use the word species (organisms of similar shape and size)

Linnean system of classification

Linnean System of Classification

  • Carolus Linnaeus simplified classification by the 18th century

  • He used binomial nomenclature that is still used today

  • When classifying, each organism receives a two-part scientific name

  • First part of any scientific name is called the genus, the second part of called the species

  • The language used is Latin which was used by scholars at that time

Linnean system of classification1

Linnean System of Classification

Example: genusspecies

Canis familiaris (dog!)

Often instead of repeating the genus we used the initial

Example: Escherichia coli becomes E coli

Please note the genus is always capitalized and the species is NOT.

System of classification

System of Classification

  • There are 7 levels or taxa of classification.

  • Taxa are used to group organisms by their similarities according to structure and/or evolutionary history.

  • Remember the first letter of this sentence:

    King Philip Came Over For Good Spaghetti

There are 7 levels of classification

There are 7 Levels of Classification

KingdomBroadest level






SpeciesMost Specific level

Levels of classification

Levels of Classification

Think of the classification system as an upside down pyramid. The Kingdom is the largest part and can hold the greatest number of organisms such as all the animals or all the plants.

As you move down the pyramid each level or ‘room’ gets smaller; it can hold fewer and fewer organisms. However, the members have more traits in common and begin to look alike.

The species is the smallest ‘room’ in the classification system and is only large enough for one kind of organism – only humans, only houseflies, etc.

Dichotomous keys

Dichotomous Keys

  • A tool allowing a scientist to determine the identity of species – a means of classifying any living species on Earth

  • Keys consist of a series of choices that lead the user to the correct name of a species

  • Dichotomous means ‘divided into 2 parts’

  • So, dichotomous keys always give 2 choices in each step

Classify shoe burger belt celery fries

Classify: shoe, burger, belt, celery, fries

  • 1.a. Clothing: Go to 2

  • 1. b. Not Clothing: Go to 3

  • 2. a. Fits on your feet: Shoes

  • 2. b. Fits around your waist: Belt

  • 3.a. Vegetable: go to 4

  • 3. b. Meat: Burger

  • 4.a. Green vegetable : Celery

  • 4. b. Not green: Fries

This can also be drawn in a classification tree

This can also be drawn in a Classification Tree:

  • Objects

  • ClothingNot Clothing

    Fits on Feet Fits around waistVegetable Meat

  • Shoes Belt Burger

  • Green Not Green

  • Celery Fries

  • …kingdoms next!



  • Before we learn exactly how biologists classify different organisms, we’re going to learn about the first taxa level: the Kingdom

  • There are 6 Kingdoms for all organisms

  • Anyone know them?

  • Animalia, Plantae, Fungi, Protista, Eubacteria, Archaebacteria

Before we examine the kingdoms

Before We Examine the Kingdoms...

Remember the CELL?????

Let’s Review:


Two types of cells

Two Types of Cells:

Compare the pictures

Compare the Pictures

Prokaryotic Cell

Eukaryotic Cell

Kingdom eubacteria

Kingdom Eubacteria

  • Have classified 4000 of 4 000 000

  • Are prokaryotes

  • Found everywhere; often called ‘true bacteria’

Kingdom archaebacteria

Kingdom Archaebacteria

  • Live in harsh, salty, acidic conditions and volcanoes

  • The first forms of life

  • Are prokaryotes

  • Only realized to be different from Eubacteria in 1996 due to advances in genetics

Kingdom protista

Kingdom Protista

  • Single celled eukaryotes

  • 115 000 species, all very diverse in cell structures, patterns of nutrition, reproduction and habitats

  • A ‘grab bag’ of organisms that do not fit into other kingdoms! Some are animal-like, fungus-like or plant-like

Examples of protista

Examples of Protista

  • Zooflagellates are animal-like protists

  • Sleeping sickenss is caused by a parasitic zooflagellate called Trypanosomagambiensis

  • Humans contract the disease if bitten by a tsetse fly infected with it

  • Once inside, zooflagellate multiplies in the bloodstream, destryoing red blood cells and attacking other tissue

  • Symptoms: fever, chills, skin rash

  • Disease can be fatal

Smear of trypanosoma gambiensis

Smear of Trypanosomagambiensis

Examples of protista1

Examples of Protista

  • Algae is a plant-like protista

  • Resemble plants because they have chloroplasts

  • Some species are single celled, others are multicellular

  • Algae perform 50 to 75% of all photosynthesis on Earth = free oxygen

Plant protista debate

Plant-Protista Debate

  • Some algae can be classified as both

  • Depends on how ‘plants’ are defined

  • But most plants have adaptations for living on land (cell walls, roots, stems) and all multicellular algae are marine; they don’t have these adaptations

  • Algae are therefore considered Protists

Kingdom fungi

Kingdom Fungi

  • Eukaryotes that build cell walls but not with cellulose like plants: FUNGI ARE NOT PLANTS!!!

  • No photosynthesis; they depend on other organisms for nutrients

  • Examples: mold, yeast, mushrooms

Examples of fungi

Examples of Fungi

Kingdom plantae

Kingdom Plantae

  • Unicellular, mostly multicellular organisms; eukaryotes

  • Cell walls contain cellulose(a complex carbohydrate that forms the main part of plant cell walls)

  • Have chloroplasts (an organelle present in algae and plant cells that contains chlorophyll and is involved in photosynthesis) & carry out photosynthesis

Examples of plantae

Examples of Plantae

Kingdom animalia

Kingdom Animalia

  • Multicellular organisms

  • Have cell membranes not cell walls

  • Cells are organized into tissues, organs and systems (e.g. – respiratory or digestive system)

  • Divided into vertebrates (backbone) and invertebrates (no backbone)

Examples of animals

Examples of Animals

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