4.1 classification of - albert einstein academy ... · level of classification ... uit is made up...
TRANSCRIPT
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
u 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
Archaeau 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 fungus-like 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?u Cladograms: shows relationships among
speciesu Grouped according to common
characteristicsu Usually the characteristics are listed
along a lineu Organisms on branches above each
characteristic have the characteristicu Organisms on branches below lack the
characteristics
HOW CAN ORGANISMS BE IDENTIFIED?Dichotomous Keyu 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