Unit 2 : Diversity of Life
Classification - Concepts and
Principles
• Scientists have identified 1.5 million kinds of
living organisms. To deal with this huge number,
biologists classify the organisms according to an
established international system. This system
allows biologists to identify an organism and place
it in the correct group with related organisms.
• The branch of biology that deals with classification
and naming of living organisms is called
taxonomy.
Classification Categories
 Kingdom
E.g. Humans
 Animalia
 Phylum
 Chordata
 Class
 Mammalia
 Order
 Primates
 Family
 Hominidae
 Genus
 Homo
 Species
 Homo sapiens
• Every single type of organism
belongs to one kingdom, one phylum,
one class, one order, one family, one
genus, and one species.
Naming Organisms
• The system for naming things is called
binomial nomenclature. It consists of naming
each species with two names. The first is the
genus name, the second is the species name.
• This system was developed at a time when
Latin was the language of scholars, and
therefore the names are in Latin. Newly
discovered organisms are still named using the
Latin language.
• The scientific name is used worldwide by
all scientists, regardless of the language
they speak.
• The present classification system consists
of 6 KINGDOMS and 3 DOMAINS .
• The 6 kingdom system of classification is
the best and most widely accepted system
in use today because of the following
reasons:
The Domains are Archaea, Bacteria, and Eukarya.
The 6 Kingdoms are
1. Archaebacteria (ancient bacteria)
2. Eubacteria (true bacteria)
3. Protista
4. Fungi
5. Plantae
6. Animalia
The Archaea and Bacteria domains contain prokaryotic
organisms. These are organisms that do not have a membrane
bound nucleus.
Eubacteria are classified under the Bacteria domain and
archaebacteria are classified as Archaeans.
The Eukarya domain includes eukaryotes, or organisms that have
a membrane bound nucleus. This domain is further subdivided
into the kingdoms Protista, Fungi, Plantae, and Animalia.
• 1. It is generally able to deal with the
discoveries of new life forms.
• 2. Its ability to cope with changing ideas
about those characteristics of greatest
importance in classifying organisms.
• 3. Able to account for the evolutionary and
biochemical relationships that have been
discovered among organisms.
Taxonomic Keys
• A taxonomic key is a guide or blueprint to
identifying organisms already classified by
taxonomists. Such keys move from general to
specific descriptions.
• The keys are dichotomous, consisting of a series
of paired statements that describe alternate
possible characteristics of the organism. These
paired statements usually deal with the presence
or absence of characteristics or structures that are
easily seen. As each pair of statements gets more
specific, a smaller grouping of organisms is
produced until the species is identified.
Sources of Evidence That We Use When
Classifying Organisms:
• 1. From fossils
• 2. From living things
Evidence from Fossils
• Fossils are one of the strongest sources of
evidence of evolution.
• Definition: A fossil is any remains or signs
of remains of an organism that lived in the
past.
• There are 4 major methods of fossil
foundation:
(A) Preservation of the Actual Organism.
• (i) Ice - some animals are permanently frozen in ice (e.g.
Wooly Mammoth)
• (ii) Amber - amber is the resin (gum) from some trees.
The resin traps insects.
• (iii) Tar Pits - naturally occurring in warmer climates.
Animals fall into these pits and their skeletal remains are
solidified along with the tar before they can decompose.
(e.g. sabre toothed tiger)
• (iv) Volcanic Ash - during volcanoes a tremendous
amount of ash is produced. This ash covers over
organisms and acts as a preservative. (e.g. reptiles)
(B) Petrification
• The organism becomes covered in water
containing a high mineral content.
Gradually, the original substances of the
organism dissolve and are replaced by
minerals from the water. The remains of
the organism are turned into stone. (e.g.
petrified tree)
(C) Carbonization
• Carbonization is a process whereby large
carbon deposits of oil, coal and gas are
produced. It is the result of large groups of
organisms that are compacted together
before they can decay. In coal deposits it is
not uncommon to find the fossils of the
organisms that produced the coal fields.
(D) Molds and Casts
• Mold - sediment in which an organism is
embedded hardens, preserving the shape of
the organism after the remains decompose.
• Cast - a mold becomes filled with minerals
and then hardens, producing a copy of the
external features of an organism.
(E) Imprint
• An imprint is formed when an impression
made in mud by a living organism is
preserved when the mud is transformed into
rock.
Evidence from Living Things
• Living organisms provide us with evidence
that development patterns, body structures
and chemical processes show similarities
that suggest a common design among some
organisms. There are four branches of
science that provide evidence which support
the concept of evolution.
(A) Comparative Embryology
• An embryo is an organism that is in the
early stages of development. Scientists
compare the structures of the embryos of
different organisms. These comparisons of
the embryological development of different
species provide evidence of their
relationship. The closer the resemblance
between the embryos, the greater the
evolutionary relationships.
(B) Comparative Anatomy
• This is a science where the anatomy of
different organisms are compared for
similarities and differences. Certain types
of similarities indicate a common
evolutionary relationship. Scientists search
for homologous structures - structures that
are found in different organisms, yet are
similar in shape, structure and origin.
Example: hearts of the various classes of
vertebrates
• Scientists also look for vestiges or vestigial
organs. These are structures that have lost their
function, but were functional in an ancestor of the
organism.
• Example - the appendix of man
(C) Comparative Biochemistry
• Scientists compare the chemical composition of
different organisms. The presence of certain
types of similar chemicals indicates a common
evolutionary relationship. The closer the
similarities, the closer the relationship between
the organisms. They look at such things as the
sequence of amino acids in the protein of
organisms.
• Example - the structure of hemoglobin of the
monkey is closely related to the hemoglobin of
humans.
(D) Genetics
• Scientists have concluded that genes are
similar in organisms that are closely related.
The more similar the DNA structures
present, the closer the evolutionary
relationship.
DOMAIN:ARCHAEA (Ancient
Bacteria)
Body type: unicellular
Prokayotic / eukaryotic: prokaryotic
Food consumption: autotrophic or heterotrophic
Reproduction: asexually
Environments: extreme environments (near volcanic activity
and dangerous stuff like that) they dont need oxygen, light
DOMAIN:ARCHAEA
EXTRA information:
Three divisions of Archaebacteria:
1.
Methanogens: methane producing organisms
2.
Thermophiles: These can live in extremely hot, acidic
environments like sulfur springs.
3.
Halophiles: Can only live in bodies of concentrated salt
water, like the Dead Sea.
Six-Kingdom System of Classification
1. Kingdom: Monera (also known as Kingdom
Archaebacteria)
(Found within Domain: Archaea)
General Characteristics:
 simple organisms lacking nuclei (prokaryotic)

either autotrophic or heterotrophic

all can reproduce asexually
Sample
Organisms:
bacteria, cyanobacteria

live nearly
everywhere
ARCHAEBACTERIA
DOMAIN: Bacteria
The bacteria of kingdom Eubacteria are heterotrophic,
autotrophic, and chemotrophic. Heterotrophs absorb organic
materials down in both living and dead organisms. Autotrophs can
make their own food by photosynthesis. Chemotrophs get their
food by breaking down inorganic matter.
Body type: unicellular
Prokayotic / eukaryotic: prokaryotic
Environments: extreme environments as do archaebacteria (near
volcanic activity)
DOMAIN:Bacteria
Extra information:
HETEROTROPHS: This bacteria lives about anywhere,
including in your body in the form of a parasite. Saprobes feed
off of non -living organisms and recycles the nutrients back into
the environment where it can be used to create new life.
AUTOTROPHS: Obtain energy through photosynthesis. Most
are a blue-green color and are often called blue-green bacteria.
They get this color from chlorophyll, which is also found in
plants. They live in chains in ponds, lakes, and moist regions.
CHEMOTROPHS: Produce energy by converting inoganic
matter into organic matter. They break down dead stuff
Kingdom: EuBacteria
Kingdom: Protista
General Characteristics:
 most are single celled; some are simple multicellular organisms (eukaryotyic)
 some are autotrophic, some are heterotrophic,
some are both
 reproduce sexually and asexually
 live in aquatic or moist habitats
Sample Organisms: simple algae, protozoa
PROTIST - Paramoeba
Kingdom: Fungi
General Characteristics:
 most are multicellular (eukaryotic)
 all are heterotrophs
 reproduce sexually and asexually
 most are terrestrial
Sample Organisms: mushrooms, yeast,
bread molds
FUNGI - LICHEN
Kingdom: Plantae
General Characteristics:
 all are multicellular (eukaryotic)
 all are autotrophs (photosynthetic)
 reproduce sexually and asexually
 most are terrestrial
Sample Organisms: seaweeds, mosses,
ferns, conifers, flowering plants
Kingdom Plantae – Air Plant Iona
Kingdom: Animalia
General Characteristics:
 all are multicellular (eukaryotic) and
heterotrophic
 most reproduce sexually
 live in terrestrial and aquatic habitats
Sample Organisms: sponges, “worms”,
lobsters, starfish, humans
Kingdom Animalia - Great Egret