Notes for B 2.3

Classification systems change as scientists learn more.

Taxonomy changes as scientists make discoveries.

• Early scientists described 2 kingdoms:

Plants: green and nonmoving

Animals: moving organisms

Three Domains

• Microscopes and other advances in technology show that there are basically 3 different types of cells.

• Kingdoms are arranged into 3 larger groups called domains: Bacteria, Archaea, and Eukarya.

Three Domains

• Bacteria: includes bacteria kingdom»No nucleus»Unicellular»Vary in how they get energy

Archaea

• Kingdom Archaea• No nucleus (prokaryotic)• Unicellular• Vary in how they obtain energy• Distinctive chemistry and live in extreme

environments

Eukarya

• Includes Kingdoms Protista, Fungi, Plantae, and Animalia

• Eukaryotic (have nuclei)• Some unicellular, most multicellular• Vary in the ways they obtain food• See chart on page B 61.

Six Kingdoms

• Plantae• Animalia• Protista• Fungi• Archaea• Bacteria• See pages 62 and 63 for an overview of all of

these kingdoms you studied in seventh grade.

The two most familiar kingdoms are plants and animals.

• Carolus Linneaus divided all the species he identified into these 2 groups.

• Plantae DNA stored in a nucleusCan carry out photosynthesis to make

sugarsContain cell walls around their cell

membraneCannot move from place to placeMulticellular

Animalia

• More than 90% of named species are insects.• Obtain energy by eating organisms or by

eating food made by other organisms• Can move around for at least part of their lives• Most have mouths and nervous systems• Have nuclei (eukaryotic)• No cell walls

Other organisms make up four more kingdoms.

• Linnaeus: called mushrooms, molds, and their relatives plants

• Archaea, Bacteria, and Protista are mostly microscopic.

• Most organisms on Earth are classified as bacterial or archaea—prokaryotic, small, and simple.

Protista

• Most unicellular• Large, complex with a true nucleus• Some eat other organisms.• Some make their own food.• Some resemble fungi. • Most live in water or sea water• Seaweeds• Some scientist think this should be divided into

different kingdoms.

Fungi

• Yeasts• Molds• Downy Mildew• Most have cell walls• Remain rooted in one place• Many act as decomposers

Archaea

• Resemble bacteria in size and shape• Genetic differences• Appear to be related to eukaryotes, but do not

have nuclei• Cell structure differs from bacteria• Live in many environs, especially the oceans• Some live in extreme environs such as geysers,

hot springs, hot vents, salty ponds etc.

Bacteria

• Live nearly everywhere on Earth• Helpful/harmful• Unicellular• Prokaryotes (no nucleus)• Most have cell walls, but not the kind plants

have• Reproduce quickly by binary fission

Species and environments change.

• Over a million species named• Estimated millions—maybe tens of millions–

not yet discovered• Species evolve over time as individual

organisms and environments change.• Changes may result in pressures that affect

living space, availability of food or other resources, or from other organisms.

•Review Questions for B 2.3

• Page 67B

Number 1

• Plantae• Animalia• Protista• Fungi• Bacteria• Archaea

Number 2

• Organisms are sorted according to general traits.

Number 3

• See pages 62-63.

Number 4

• Plants use the sun’s energy and air to make sugars.

• Fungi take in nutrients from their surroundings.

Number 5

• No—does not have a nucleus

• Yes—the membrane and DNA are like a nucleus

Quiz B 2.3

• Fill ins: Animalia Archaeaspecies ProtistaBacteria FungiDomains Plantae(6 terms used)

What are the 3 domains? List 2 traits that are used to classify organisms into each domain.