Biology Notes Chapter 15

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Biology Notes Chapter 15

• Classification Systems

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Why Classify?

• In order to work with the diversity of life, we
  need a system of biological classification that
  names orders living organisms in a logical
  manner.
• There are more than 2.5 million species already
  identified and millions more possibly
  undiscovered.
• Scientists use a universal method of naming
  organisms, so that no matter where in the world
  you may go, the names of the different organisms
  will be the same.

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Biological Classification.

• Carolus Linnaeus, is the father of the modern
  classification system used by scientists.
• Linnaeus came up with the system of binomial
  nomenclature, which is a two-name system.
• The two names are the genus and species of an
  organism.
• The genus is always capitalized and the species
  is never capitalized.
• Both names are always printed in italicized
  letters.

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The Classification System of Linnaeus

• The branch of science of naming organisms and
  assigning them to groups is called taxonomy.
• Organisms are classified into groups of differing
  levels of relatedness.
• The levels of relatedness from the most broad to
  the most specific are
• Kingdom, phylum, class, order, family, genus,
  species

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Species

• Species is the most specific of the levels of
  relatedness.
• Species is defined as a population of organisms
  that share similar characteristics and that can
  breed with one another and produce viable
  offspring.

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Genus

• The next larger taxon is the genus.
• All the various species included in the same
  genus have many common characteristics.
• For example the common house cat has the genus
  Felis and the species domesticus. The mountain
  lion has the genus Felis and the species
  concolor.
• These two cats share many common characteristics,
  but they are not able to interbreed and produce
  viable offspring.

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Family

• A family is a larger taxon than genus or species.
  
• All members of a genus will belong to the same
  family.

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Order

• Several families of similar organisms make up the
  next larger group called order.
• For example cats are in the order Carnivora.
• All members of the order Carnivora are meat
  eaters or carnivores.

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Classes

• Orders are grouped into classes.
• Classes are based on common characteristics to
  many orders.
• For example, warm blooded animals that have hair
  are members of the class Mammalia.

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Phylum

• Several classes are placed in a phylum.
• A phylum will consist of a large number of very
  different organisms.
• These organisms share some important
  characteristics.
• For example mammals are placed in phylum Chordata
  along with birds, fishes, and reptiles because
  all of them share certain similar
  characteristics.

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Kingdoms

• Kingdom is the largest broadest group wit the
  least amount of relatedness.
• Different kingdoms are those such as Plantae,
  Animalia, Fungi, Protista, Monera

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Memory Aid For The Different Levels Of
Organization

• The phrase King Phillip Came Over For a Good
  Supper may help you remember the different
  levels of organization.
• Kingdom, Phylum, Class, Order, Family, Genus,
  Species

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Taxonomy And Evolutionary Relationships

• Species shown to be closely related are
  classified together.
• Other species that may look alike but possess
  analogous structure only, are classified in
  different groups.
• Taxonomists attempt to group organisms in ways
  that show their evolutionary relationships.
• They do this by identifying and studying
  homologous structures in adult organisms, in
  developing embryos, and in well preserved
  fossils.

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Biochemical Taxonomy

• All organisms share many important organic
  molecules that are almost but not exactly
  identical from species to species.
• Mammals, birds, amphibians, reptiles, and fishes
  have hemoglobin in their blood, but each species
  has a slightly different variety of it.

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Biochemical Taxonomy

• Biochemists use these similarities and
  differences among the compounds of life to
  classify organisms.
• The can use DNA and RNA to classify organisms.
• For example studies of DNA show that humans and
  chimpanzees have DNA that differs in less than 1
  of their nucleotide sequence.

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The Five Kingdom System

• The five kingdoms are Monera, Protista, Fungi,
  Plantae, and Animalia.

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Monera

• The kingdom Monera, contains all prokaryotes.
• Prokaryotes lack a true nucleus, mitochondria,
  and chloroplasts.
• Monerans are placed at the bottom of the
  evolutionary tree or ladder.

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Protista

• Unlike prokaryotes, all eukaryotes possess
  membrane-enclosed organelles, and contain a true
  nucleus.
• All single celled eukaryotes are placed in the
  kingdom Protista.
• The kingdom Protista is divided into three
  groups.
• Animal like protists
• Plant-like protists
• Fungus like protists

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Fungi

• Members of the kingdom Fungi build cell walls
  that do not contain cellulose.
• Fungi are heterotrophic, which means that they do
  not make their own food by photosynthesis.
• Although fungi have many nuclei, they do not
  always have separate cells divided by complete
  cell walls.
• It is for these reasons that fungi are not
  included with the plants and are placed in their
  own kingdom.

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Plantae

• Members of the kingdom Plantae are multicellular
• They have cell walls that contain cellulose.
• They are autotrophic which means they make their
  own food in photosynthesis.

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Animalia

• Members of the Animalia kingdom are
  multicellular.
• They are heterotrophic.
• All have cell membranes without cell walls.

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Test Review

• The scientific name for a __ would be Homo
  sapiens.
• The smallest taxon is __.
• The difference between a plant and a plant like
  protists is that the protists is ___.
• The animal that has the closest DNA match of a
  human is the __.
• A eukaryotic organism that has a cell wall that
  lacks cellulose is a (an) __.
• In the present system of taxonomy, the least
  clear division of kingdoms is between the
  multicellular kingdoms and the ___.

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Test Review

• All Monerans contain a __. (chloroplast, cell
  membrane, nucleus, mitochondria)
• Any good classification systems does not use
  different scientific names for the same organism.
  (True or False)
• The double naming system introduced by Linnaeus
  is know as _.
• Many species of protists straddle the line
  between single celled and multicellular plans,
  animals, and fungi. Why are these species so
  important to biologists?

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Test Review

• Why is it more difficult to classify a newly
  found fossil of an animal than newly found living
  animals?
• Why are organisms sometimes moved from one taxon
  to another?
• A newspaper article states that a new blend of
  Milo wheat will be planted next year. This blend
  was developed by crossbreeding different types of
  wheat. This article is referring to a new species
  of wheat. How do you know that this will be a new
  species instead of a new genus.

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Test Review

• Describe the relationship between the common
  housecat, Felis domesticus and the African
  leopard, Felis pardus.
• The unifying biological principle in modern
  classification systems is the __ theory.
• Carnivores are __
• If a one celled organism contains membrane
  enclosed organelles , it must be a __.

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Test Review

• The only taxon with a clear biological identity
  is the __.
• Cats, dogs, and lions are in the ___ order.
• In classifying organisms, orders are grouped into
  __.
• Solely from its name, you know that Rhizopus
  niqricans must be
• a. a plant b. an animal c. In the species
  niqricans
• The third smallest taxon in the Linnaeus system
  of classification is the __.