Download PGS: 549 – 554

Kingdom Protista
I.
Protista
A. Most of these organisms are uni-cellular.
B. All are very complex generalists. (Meaning they can do all that your WHOLE body does.)
C. Means of nutrition (feeding) for these organisms:
1. Heterotroph (Feeds on other organisms.)
a. Most of these organisms are this type.
b. Also includes the Animal – like prtotists. (These are protozoa or zooplankton.)(“zoa” means “animal”)
c. Also includes the Fungus – like protists.
2. Photoautotroph (Photosynthesizers)
a. Some of the main clades are this type.
b. Also includes the Plant – like protists. (These are the algae and phytoplankton.)
3. Mixotroph (These organisms can obtain energy either way listed above.)
D. Most organisms are motile.
1. They use flagella, cilia, or pseudopodia to move through the water or other liquid.
E. Reproductive Means
1. Most are sexually reproducing organisms. (Remember, this method favors variation.)
2. Some are asexual. (This is a faster process but produces no variation; they are all clones.)
F. Habitats of these organisms
1. These are mostly aquatic organisms. (Most are important parts of aquatic food chains or webs.)
2. Some organisms are symbiotic parasites.
II. ENDOSYMBIOTIC HYPOTHESIS (1960)
A. This was proposed by Lynn Margulis.
B. It proposes that smaller prokaryotes were engulfed larger prokaryotes. Ultimately, this led to a symbiotic relationship
between host and “parasite”. This symbiosis eventually led to the evolution of a heterotrophic eukaryotic cell.
The smaller prokaryote provided energy for the larger organism while the larger “host” provided food and
protection.
The evolution of the eukaryotic cell set the stage for the adaptive radiation of the Domain Eukarya, and eventually
over hundreds of millions of years, to the evolution of Kingdoms Fungi, Plantae, and Animalia.
C. Supporting evidence – Mitochondria, Chloroplasts, Flagella
III. Examples of protists include:
A. Animal – like Protists (A.K.A. protozoa.) (“Proto” means “first”; “zoa” means “animal”)
1. These catch and eat other organisms, they’re heterotrophic, just like animals
2. Some move using Pseudopodia (e.g. Amoebas)
3. Some move using Cilia (e.g. Paramecium)
4. Some move using flagella (e.g. Trypanosoma,)
5. Some don’t move at all
B. Fungus – like Protists (A.K.A. Mycetozoa – fungus animals) (“mycota” means “fungus”)
1. These feed on decaying organisms as they are decomposers.
C. Plant – like Protists
1. These organisms perform photosynthesis, just like plants. These organisms are collectively called
algae.
2. These plant-like protists produce the majority of atmospheric oxygen, and serve as primary producers
in almost all aquatic ecosystems.
3. Many of these algae are multicellular.