1. Chapter 21 PROTISTA

2. A. The Basal Eukaryotes Includes several distantly related groups; believed to be the earliest unicellular eukaryotes to diverge. 1. Basal Eukaryotes Lacking Mitochondria Ancestors of these organisms may have diverged before the endosymbiotic event that gave rise to mitochondria.

3. ] Parabasalia - flagellated organisms found only in association with animals. Trichomonas vaginalis causes the STD trichomoniasis. Trichonympha live in termites; contain bacteria that digest cellulose. ] Diplomonadida - flagellated organisms found in stagnant fresh water or in intestines. Giardia lamblia causes “hiker’s diarrhea”.

4. 2. Basal Eukaryotes With Mitochondria ] Amoebae - aquatic organisms that use pseudopodia to move & to feed. Amoeba proteus ] Acellular slime molds - heterotrophic organisms that exist as an amoeboid mass called a plasmodium. Physarum

5. ] Cellular slime molds - heterotrophic organisms that exist as single cells. When food is lacking, cells aggregate to form a multicellular slug.

6. ] Euglenida - organisms that possess an anterior chamber from which one or two flagella emerge. Euglena is a pond dwelling organism; has both plant & animal characteristics.

7. ] Kinetoplastida (trypanosomes) - flagellated organisms; have a single, large mitochondrion containing a kinetoplast (houses extracellular DNA). Trypanosoma brucei causes African sleeping sickness; transmitted to humans by bite of tsetse fly.

8. B. The Alveolates Includes protists that have alveoli beneath the cell membrane. 1. Dinoflagellates - organisms possessing a pair of flagella that cause the cell to spin as it swims; major components of phytoplankton. Gonyaulax “blooms” cause red tides. Pfiesteria piscicida has 24 stage life cycle.

9. 2. Ampicomplexans - obligate parasites of animals; all possess an apical complex & have complex life cycles. Plasmodium causes malaria; transmitted to humans by mosquitoes. Toxoplasma gondii causes toxoplasmosis; pregnant woman can become infected via cat feces & pass disease to fetus.

10. 3. Ciliates - organisms that move by means of cilia. Paramecium Didinium

11. C. The Stramenopiles Includes protists that have unique flagella & laminarin; photosynthetic stramenopiles have pigments not found in plants. 1. Water molds (oomycetes) - absorb nutrients from their surroundings. Plasmopara viticola causes downy mildew of grapes. Phytophthora infestans causes late blight of potatoes.

12. 2. Diatoms - organisms that have two- part silica walls called frustules; major components of phytoplankton. Abrasiveness of frustules makes diatoms useful ingredients in polishes.

13. 3. Brown algae - large, multicellular seaweeds; brown color is due to the photosynthetic pigment fucoxanthin. Giant kelp 4. Golden algae - most are unicellular; golden color is due to carotene & xanthophyll photosynthetic pigments. When light or nutrient supplies dwindle, many will consume bacteria or diatoms.

14. D. The Red Algae Primarily multicellular; have photosynthetic pigments called phycobilins. Useful red algal products include: F agar - used as a culture medium for microbes, and to thicken ice cream & yogurt. F carageenan - used to stabilize paints, cosmetics & creamy foods.

15. E. The Green Algae Includes unicellular, multicellular & colonial autotrophs that resemble plants. Plant-like characteristics: F use chlorophyll a & b F store starch F have cell walls containing cellulose F most exhibit alternation of generations

16. Life cycle of the sea lettuce, Ulva

17. Green algae differ from plants: F most have pyrenoids (regions in chloroplasts that store starch) F lack true stems, roots & leaves Spirogyra - multicellular filaments containing spiral- shaped chloroplasts. Volvox - colonial organism consisting of 500 to 600,000 biflagellate cells.