[3]Protists - Protists(Chapter 25 1 Protists are...

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chlamydomonas Ulva Protists (Chapter 25) 1. Protists are unicellular eukaryotes. Name 5 characteristics that differentiate them from prokaryotes. Do they undergo sexual reproduction; meiosis and/or mitosis? Mostly unicellular eukaryotic organisms that live in aquatic environments Unlike prokaryotes, contain nuclei and other membrane-enclosed organelles (e.g. mitochondria, 9+2 flagella, multiple chromosomes and chromatin o Sexual and asexual reproduction and meiosis mitosis 2. As microscopic unicellular organisms, they vary greatly in size, depending upon their environment and life cycle: Differentiate between a colony, coenocytes and how does a coenocytes differ from a multicellular protest? Sizes of protists o Unicellular organisms – size variable Microscopic Colonies o Loosely connected groups of cells Coenocytes o Multicellulate masses of cytoplasm o Multicellular organism composed of many cells o Still simple in body form – without specialized tissues 3. Chlamydomonas is a unicellular protest; describe its structure – does it have one or two flagella(e)? (fig. 25-1) Chlamydomonas o A unicellular protest Protest kingdom 4. What are the three main modes of locomotion for the protista members? Do some members have more than one mode of locomotion; are they all motile? o Locomotion Pseudopodia Flagella Combination of both pseudopodia and flagella Cilia Some are nonmotile 5. Some protist are nutritional autotrophs, while others are heterotrophs. Can autotrophs revert to being heterotrophs if the conditions dictate? Why would this be necessary? o Nutrition Protist obtain their nutrients autotrophically (photosynthesis) or heterotrophically (obtain by absorption) Or a mixture of both 6. Protist can live in a symbiotic relationship; discuss the terms mutualism, commensalism, and parasitism from the perspective of how each relationship affects the members involved. o Interactions Free living or symbiotic Symbiotic relationships range from mutualism (equal partners), commensalism (one partner benefits, other unaffected) to parasitism
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7. Most protists live in aquatic environments (oceans (plankton), freshwater ponds, lakes, and streams). In parasitic relationship how does this hold true? o Habitats Most protists live in Oceans Fresh water ponds Lakes Streams Parasitic protists live in bodily fluids of hosts 8. Many protist reproduce both sexually and asexually. Do they develop multicellular reproductive organs or embryos? Do all members undergo sexual and asexual reproduction? o Reproduction Many produce both (sexually/asexually) Do not develop multi-cellular reproductive organs or embryos Others reproduce only asexually 9. Can you explain the evidence that supports serial endosymbiosis as the evolutionary path for the protists, with respect to the development of organelles such as mitochondria and chloroplasts? (Fig. 25-2) How does secondary endosymbiosis explain the three and four membranes chloroplasts seen, in members like dinoflagellates?
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