Living Systems

Chapter Three: Classifying Living Things

• 3.1 Types of Living Things

• 3.2 Dichotomous Keys

3.1 Types of living things• Living things are

classified by similar characteristics.

• Each different type of organism is called a species.

• It is estimated that there are over ten million different species on Earth.

All of the same kind of dust mite are members of a single species.

3.1 Classifying life

• One system of classification groups all living things into one of six kingdoms:

• Fungi

• Plantae

•Animalia

•Archaebacteria

• Eubacteria

• Protista

3.1 Classifying life

• To classify a living thing into one of the kingdoms, scientists ask 3 questions:

1. Does it have prokaryotic (simple) cells or eukaryotic (complex) cells?

2. Is it single-celled (one-celled) or multicellular (many-celled)?

3. Does it get energy by making its own food (as a producer) or by getting food from other organisms (as a consumer)?

3.1 Two kingdoms of bacteria

• Bacteria are the simplest of all living things.

• They are single-celled organisms and their cells do not have a nucleus.

• Some bacteria can produce their own food.

• Others break down food and absorb it.

Kingdom Archaebacteria

Kingdom Eubacteria

3.1 Protists• Members of the

Kingdom Protista are called protists.

• Protists are an odd group of organisms because they have many different characteristics.

3.1 Fungi• Fungi are important because they break down

rotting things and return the nutrients to the soil.• Kingdom Fungi includes the fungi, mushrooms,

molds, and yeasts.

3.1 Plants• The Kingdom Plantae is made up of multicellular

organisms whose cells have a nucleus.• In photosynthesis, plants convert energy from the

sun and store it in the form of molecules.

3.1 Animals• Animals are multicellular organisms with cells that

have a nucleus.• Beetles, worms, snakes, and birds are classified

into the Kingdom Animalia.

3.1 Plant and Animal kingdomscompared

3.1 Classifying life

• Taxonomy is the process of identifying and classifying living things.

• A Swedish scientist and explorer named Carolus Linnaeus (1707–1778) developed a system of classification in the 1700s.

• There are currently seven levels of classification.

3.1 Levels of classification

• Organisms with shared characteristics are grouped together.

• What characteristic do these organisms share?

3.1 Levels of classification• For animals, the levels of classification are:

kingdom, phylum, class, order, family, genus, and species.

•At what level are these two animals classified differently?

3.1 Scientific Names

• A scientific name is the two-part, scientifically recognized name given to an organism, consisting of its genus and species.

3.1 Scientific Names• You may have a

difficult time understanding scientific names because they are usually in Latin or Greek.

• Felis is Latin for “cat” and domesticus is Latin for “domesticated.”