Protists

1.A protist is any organism that is not a plant, an animal, a fungus, or a prokaryote.

2. Protists are eukaryotic. 3. Most protists are unicellular and some protists are multicellular.

4. Protists are in the Kingdom Protista. In Latin, protista means “the very first”. 5. Some scientists believe that protists were the first eukaryotic organisms on Earth that evolved from a symbiosis of several cells.

6. No. Not all scientists agree on how to classify the protists. The book classifies the protists according to the way they obtain nutrition.

7. The three groups of protists are: Animal-like protists – eat things and are heterotrophs. Plant-like protists – produce their own food by photosynthesis. Fungus-like protists – obtain their food by external digestion (decomposers or parasites).

8. This method of classifying protists does not reflect their evolutionary history. 9. Animal-like protists were called protozoa. Protozoa means “first animals”. 10. Animal-like protists are heterotrophs. 11. Animal-like protists are distinguished from one another by their means of movement.

12. The four phyla of animal-like protists are: Zooflagellates – propelled by whip-like tails called flagella. Sarcodines – move via temporary cytoplasmic extensions known as pseudopods. Ciliates – move using short hair-like projections called cilia. Sporozoans – do not move.

13. Animal- like protists are important to the oceans because they are the first link in the food chain in many aquatic ecosystems.

14. Some animal-like protists cause serious diseases. Here are a few: Plasmodium – causes malaria. Trypanosoma – causes African sleeping sickness. Entamoeba – causes amebic dysentery. Giardia – causes severe diarrhea and digestive system problems.

15. Three essential roles that protists play in the environment are: Some live symbiotically within other organisms Others recycle nutrients by breaking down dead organic matter Many are eaten by small animals that are, in turn, eaten by larger ones

16. Plant-like protists are like plants because they undergo photosynthesis. 17. Plant-like protists are commonly called algae.

18. The plant-like protists are divided into four phyla: Euglenophytes Chrysophytes Diatom Dinoflagellates

19. One of the key traits used to identify algae is the type of photosynthetic pigments they contain. 20. The three forms of chlorophyll are chlorophyll a, chlorophyll b, and chlorophyll c. Each form absorbs different wavelengths of light.

21. Accessory pigments are compounds that absorb light at different wavelengths than chlorophyll. 22. Together, chlorophyll and accessory pigments allow algae to harvest and use the energy from sunlight.

23. Algae have a wide range of colors because they reflect different wavelengths of light. 24. Plant-like protists play a major role on Earth. They are important organisms whose position at the base of the food chain makes much of the diversity of aquatic life possible.

25. Phytoplankton are small, photosynthetic organisms found near the surface of the ocean. They provide a direct source of nourishment for aquatic organisms. 26. An algal bloom is a huge mass of algae that grows and depletes the water of nutrients and oxygen. Sewage discharge into bodies of water causes them.

27. Multicellular algae are different than unicellular algae because they are multicellular. 28. These types of algae are typically referred to as seaweed.

29. The three phyla of multicellular algae are red algae, brown algae, and green algae. They differ because of their photosynthetic pigments. 30. Multicellular algae are important to the oceans because they are a major food source for life in the oceans.

31. Algae produce much of the Earth’s oxygen through photosynthesis. About half of all the photosynthesis that occurs on Earth is performed by algae.

32. The human uses of multicellular algae include: Used to make medicines for stomach ulcers, high blood pressure, arthritis, and other health problems Used in foods such as sushi, ice cream, salad dressing, pudding, pancake syrup, eggnog and candy bars Used to make plastics, waxes, transistors, deodorants, paints, lubricants, and artificial wood Used to make agar for culturing bacteria

33. Fungus-like protists live in damp, nutrient- rich environments. 34. They get their food by digesting it outside of their bodies and absorbing food through their cell membranes.

35. Like fungi, the fungus-like protists are heterotrophs that absorb nutrients from dead or decaying organic matter. 36. Unlike most true fungi, fungus-like protists have centrioles but lack chitin in their cell walls.

37. The fungus-like protists include the cellular slime molds, the acellular slime molds, and the water molds.

38. Slime molds and water molds are important as recyclers of organic material. 39. The dark, rich topsoil that provides plants with nutrients comes from the decomposition of dead animals and plants.

40. Some fungus-like protists can harm living things. Phytophthora infestans is the protist that caused the Great Potato Famine. In 1845, this organism killed about 60 % of the Irish potato crop, and in 1846 it killed almost the entire crop. This led to mass starvation resulting in the death of around 1 million people. Another million Irish people emigrated to the United States.