Download File

4.1 Classification of
Living Things Part 2
WHAT ARE THE THREE DOMAINS?
u
Kingdoms used to be the highest
level of classification
u
Scientists noticed that organisms in
two of the kingdoms different
greatly from organisms in the other
four
u
A domain represents the largest
differences among organisms
Bacteria
Bacteria contain all organisms within
Kingdom Bacteria
u It is made up of prokaryotes that usually
have a cell wall and reproduce by cell
division
u Prokaryotes – single-celled organisms that
lack a cell nucleus
u They live in almost any environment
u
Archaea
u
Archaea include all organisms
in Kingdom Archaea
u
Made up of prokaryotes that
reproduce by cell division
u
They have differences in
their genetics and their cell
walls when compared to
bacteria
u
Many live in harsh
environments
Eukarya
u
Eukaryotes are made up of cells that
have a nucleus and membrane-bound
organelles
u
Eukaryotic cells are more complex than
prokaryotic cells and usually larger
u
Some eukaryotes like protists and some
fungi are single-celled while most
others are multicellular
u
Eukarya is made up of all eukaryotes
WHAT ARE THE FOUR
KINGDOMS IN EUKARYA?
Kingdom Protista
u
Protista, called protists, are single-celled or
multicellular organisms like algae or slime molds
u
Very diverse
u
They can have plant-like, animal-like, or funguslike characteristics
u
Some produce sexually (with a partner) or
asexually (without a partner)
u
Algae are autotrophs (make their own food)
u
Some are heterotrophs (eat other organisms for
food)
Kingdom Plantae
u
Consists of multicellular organisms
that have cell walls mostly made of
cellulose
u
Plants are autotrophs
u
Found on land and in water that light
can pass through
u
Some reproduce asexually (like
potatoes) while others reproduce
sexually (like flowers with pollen)
u
Cannot move by themselves
Kingdom Fungi
u
Fungi are heterotrophs
u
Cell walls contain chitin
u
Fungal cells do not have chloroplasts
u
Single-celled or multicellular,
includes yeasts, molds, and
mushrooms
u
They use digestive juices to break
down materials around them for food
u
Reproduce sexually, asexually, or both
ways depending on their type
Kingdom Animalia
u
Animalia contains multicellular
organisms that lack cell walls
u
Do not have chloroplasts
u
Heterotrophs
u
Have specialized sense organs
u
Most can move on their own
u
Most animals reproduce sexually but
a few can asexually (through
budding)
HOW DO CLASSIFICATION SYSTEMS
CHANGE OVER TIME?
u
Millions of organisms have been identified and classified
but millions have yet to be discovered and named
u
Scientists are still identifying new species which may not
fit into existing categories
u
Many scientists argue that protists are so different from
one another that they should be classified into several
kingdoms instead of one
u
The number of kingdoms may change as new data are
collected
HOW DO BRANCHING DIAGRAMS SHOW
CLASSIFICATION RELATIONSHIPS?
Cladograms: shows relationships among
species
u Grouped according to common
characteristics
u Usually the characteristics are listed
along a line
u Organisms on branches above each
characteristic have the characteristic
u Organisms on branches below lack the
characteristics
u
HOW CAN ORGANISMS BE IDENTIFIED?
Dichotomous Key
u
Dichotomous key uses a series of paired statements to
identify organisms
u
Each pair of statements is numbered
u
When identifying an organism, each pair of statements is
read
u
Then the statement that best describes the organism is
chosen
u
Either the chosen statement identifies the organism or it will
direct you to another pair of statements
u
Some dichotomous keys are set up as diagrams instead of
tables