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75 Cards in this Set
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What 2 things are important to bear in mind about protists and their relation to eukaryotic lineages?
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Protists are eukaryotes
Eukaryotic cells have organelles and are more complex than prokaryotic cells It is important to bear in mind that 1. The organisms in most eukaryotic lineages are protists 2. Most protists are unicellular |
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How does the structural and functional diversity of protists compare with other groups of eukaryotes?
What type of cellular species are most protists? How is it possible that single-celled protists can be very complex? |
Protists exhibit more structural and functional diversity than any other group of eukaryotes
Though most protists are unicellular, there are some colonial and multicellular species Single-celled protists can be very complex, as all biological functions are carried out by organelles in each individual cell |
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What are the 3 nutrition types of protists?
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Protists, the most nutritionally diverse of all eukaryotes, include:
1. Photoautotrophs, which contain chloroplasts 2. Heterotrophs, which absorb organic molecules or ingest larger food particles 3. Mixotrophs, which combine photosynthesis and heterotrophic nutrition |
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How can protists reproduce? What processes are involved?
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Some protists reproduce asexually, while others reproduce sexually, or by the sexual processes of meiosis and fertilization
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Why are amitochondriates no longer considered the oldest lineage of eukaryotes?
One hypothesis separates eukaryotes into what divisions? |
Four Supergroups of Eukaryotes
It is no longer thought that amitochondriates (lacking mitochondria) are the oldest lineage of eukaryotes Many protists have been shown to have mitochondria and have been reclassified Our understanding of the relationships among protist groups continues to change rapidly One hypothesis divides all eukaryotes (including protists) into four supergroups |
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From where does protist diversity have its origins?
What is endosymbiosis? |
There is now considerable evidence that much protist diversity has its origins in endosymbiosis
Endosymbiosis is a relationship between two species in which one organism lives inside the cell or cells of the other organism (the host) |
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From what are mitochondria and plastids derived from?
Mitochondria evolved once by endosymbiosis of what organism? How did plastids evolve later on? |
Mitochondria and plastids are derived from prokaryotes that were engulfed by the ancestors of early eukaryotic cells
Mitochondria evolved once by endosymbiosis of an alpha proteobacterium Plastids evolved later by endosymbiosis of a photosynthetic cyanobacterium The ancestral host cell may have been an archaean or a “protoeukaryote,” from a lineage related to, but diverged from archaeal ancestors |
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How did mitochondria first arise?
How did the plastid lineage later evolve? The protists of the plastid-bearing lineage evolved into what? |
Mitochondria arose first through descent from a bacterium that was engulfed by a cell from an archaeal lineage
The plastid lineage evolved later from a photosynthetic cyanobacterium that was engulfed by a heterotrophic eukaryote The plastid-bearing lineage of protists evolved into photosynthetic protists, red and green algae |
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Illustrate the arrival of plastids, beginning with the most recent common ancestor.
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Like cyanobacteria, plastids of red algae and green algae have what?
Transport proteins in the membranes of red and green algae are homologous to what? |
Like cyanobacteria, plastids of red algae and green algae have two membranes
Transport proteins in the membranes of red and green algae are homologous to those found in cyanobacteria |
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On several occasions during eukaryotic evolution, what did red and green algae undergo, and what were they ingested by?
How did chlorarachniophytes likely evolve? What is a nucleomorph? |
On several occasions during eukaryotic evolution, red and green algae underwent secondary endosymbiosis, in which they were ingested by a heterotrophic eukaryote
For example, chlorarachniophytes likely evolved when a heterotrophic eukaryote engulfed a green alga The engulfed cell contains a vestigial nucleus called a nucleomorph |
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Illustrate the basic morphology of the Chlorarachniophyte.
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The clade Excavata is characterized by what?
Some members have an “excavated” what? This group includes what three groups of organisms? |
Concept 28.2: Excavates include protists with modified mitochondria and protists with unique flagella The clade Excavata is characterized by its cytoskeleton Some members have an “excavated” feeding groove This group includes the diplomonads, parabasalids, and euglenozoans |
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Diplomonads and Parabasalids lack/possess what organelles? Where do they live?
What are mitosomes? Where do diplomonads derive energy from? Comment on the nuclei and flagella of diplomonads. |
Diplomonads and Parabasalids -These two groups lack plastids, have modified mitochondria, and most live in anaerobic environments Diplomonads -Have reduced mitochondria called mitosomes -Derive energy from anaerobic biochemical pathways -Have two equal-sized nuclei and multiple flagella Are often parasites, for example, Giardia intestinalis |
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What are hydrogenosomes in Parabasalids?
What pathogenic Parabasalid causes yeast infections? |
Parabasalids Have reduced mitochondria called hydrogenosomes that generate some energy anaerobically Include Trichomonas vaginalis, the pathogen that causes yeast infections in human females |
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What nutrional types are found in the Euglenozoa clade?
What distinguishes Euglenozoa as a clade? What else does this clade include? |
Euglenozoans Euglenozoa is a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites The main feature distinguishing them as a clade is a spiral or crystalline rod inside their flagella This clade includes the kinetoplastids and euglenids |
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Describe the mitochondrion of kinetoplastids.
What do free-living species of kinetoplastids consume? What are examples of pathogenic kinetoplastids? |
Kinetoplastids Kinetoplastids have a single mitochondrion with an organized mass of DNA called a kinetoplast Free-living species are consumers of prokaryotes in freshwater, marine, and moist terrestrial ecosystems Some species are parasitic Kinetoplastids in the genus Trypanosoma cause sleeping sickness in humans Another pathogenic trypanosome causes Chagas’ disease |
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How do trypanosomes evade immune responses?
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Trypanosomes evade immune responses by switching surface proteins A cell produces millions of copies of a single protein The new generation produces millions of copies of a different protein These frequent changes prevent the host from developing immunity |
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Describe Euglenids (in a nutshell)?
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Euglenids Euglenids have one or two flagella that emerge from a pocket at one end of the cell Some species can be both autotrophic and heterotrophic |
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Illustrate the morphology of Euglenids.
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Describe the naming of the SAR clade.
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Concept 28.3: The “SAR” clade is a highly diverse group of protists defined by DNA similarities The “SAR” clade is a diverse monophyletic supergroup named for the first letters of its three major clades stramenopiles, alveolates, and rhizarians This group is one of the most controversial of the four supergroups |
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Illustrate the phylogeny of the SAR clade.
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Describe Stramenopiles and their morphology.
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Stramenopiles The stramenopiles clade includes some of the most important photosynthetic organisms on Earth Most have a “hairy” flagellum paired with a “smooth” flagellum Stramenopiles include diatoms, golden algae, and brown algae |
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What are Diatoms?
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Diatoms Diatoms are unicellular algae with a unique two-part, glass-like wall of silicon dioxide |
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Describe Golden Algae.
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Golden Algae Golden algae are named for their color, which results from their yellow and brown carotenoids The cells of golden algae are typically biflagellated, with both flagella near one end All golden algae are photosynthetic, and some are mixotrophs Most are unicellular, but some are colonial |
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What are Brown Algae?
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Brown Algae Brown algae are the largest and most complex algae All are multicellular, and most are marine Brown algae include many species commonly called “seaweeds” |
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Describe the habitat and morphology of different seaweeds.
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Giant seaweeds called kelps live in deep parts of the ocean Brown algal seaweeds have plantlike structures: the rootlike holdfast, which anchors the alga, and a stemlike stipe, which supports the leaflike blades Similarities between algae and plants are examples of analogous structures |
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Illustrate the 3 main structural features of the Brown algal seaweeds.
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Describe the idea of Alternation of Generations.
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Alternation of Generations A variety of life cycles have evolved among the multicellular algae The most complex life cycles include an alternation of generations, the alternation of multicellular haploid and diploid forms Heteromorphic generations are structurally different, while isomorphic generations look similar |
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What is the function of zoospores?
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The diploid sporophyte produces haploid flagellated spores called zoospores The zoospores develop into haploid male and female gametophytes, which produce gametes Fertilization of gametes results in a diploid zygote, which grows into a new sporophyte |
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Illustrate the life cycle of zoospores, including meiosis and fertilization.
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Write a few notes on the clade Alveolata.
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Alveolates Members of the clade Alveolata have membrane-enclosed sacs (alveoli) just under the plasma membrane The alveolates include: 1. Dinoflagellates 2. Apicomplexans 3. Ciliates |
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Describe the morphology, habitat, and nutritional type of dinoflagellates.
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Dinoflagellates Dinoflagellates have two flagella and each cell is reinforced by cellulose plates They are abundant components of both marine and freshwater phytoplankton They are a diverse group of aquatic phototrophs, mixotrophs, and heterotrophs Toxic “red tides” are caused by dinoflagellate blooms |
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What causes Red tide in the Gulf of Carpentaria in Northern Australia.
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Describe Apicomplexans, their morphology, and their basic life cycle.
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Apicomplexans Apicomplexans are parasites of animals, and some cause serious human diseases They spread through their host as infectious cells called sporozoites One end, the apex, contains a complex of organelles specialized for penetrating host cells and tissues Most have sexual and asexual stages that require two or more different host species for completion |
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Write a few notes on Plasmodium and the effect of malaria on humans.
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The apicomplexan Plasmodium is the parasite that causes malaria Plasmodium requires both mosquitoes and humans to complete its life cycle Approximately 900,000 people die each year from malaria Efforts are ongoing to develop vaccines that target this pathogen |
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Illustrate the life cycle of Plasmodium.
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Describe the morphology and sexual characteristics of Ciliates.
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Ciliates Ciliates, a large varied group of protists, are named for their use of cilia to move and feed They have large macronuclei and small micronuclei Genetic variation results from conjugation, in which two individuals exchange haploid micronuclei Conjugation is a sexual process, and is separate from reproduction, which generally occurs by binary fission |
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Write a few notes on Rhizarians, commenting on their unique morphology.
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Rhizarians Many species in the rhizarian clade are amoebas Amoebas are protists that move and feed by pseudopodia, extensions of the cell surface Rhizarian amoebas differ from amoebas in other clades by having threadlike pseudopodia Rhizarians include radiolarians, forams, and cercozoans |
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Write a few notes on Radiolarians.
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Radiolarians Marine protists called radiolarians have delicate, symmetrical internal skeletons that are usually made of silica Radiolarians use their pseudopodia to engulf microorganisms through phagocytosis The pseudopodia of radiolarians radiate from the central body |
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Describe the morphology of Forams.
What does the magnesium content in fossilized forams tell us? |
Forams Foraminiferans, or forams, are named for porous, generally multichambered shells, called tests Pseudopodia extend through the pores in the test Many forams have endosymbiotic algae Foram tests in marine sediments form an extensive fossil record Researchers can use measures of the magnesium content in fossilized forams to estimate changes in ocean temperature over time |
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Describe the Cercozoans.
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Cercozoans Cercozoans include most amoeboid and flagellated protists with threadlike pseudopodia They are common in marine, freshwater, and soil ecosystems Most are heterotrophs, including parasites and predators |
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What is Paulinella chromatophora?
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Paulinella chromatophora is an autotroph with a unique photosynthetic structure called a chromoatophore This structure evolved from a different cyanobacterium than the plastids of other photosynthetic eukaryotes |
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Describe the arrival of red algae and green algae.
What supergroup includes them? |
Concept 28.4: Red algae and green algae are the closest relatives of land plants Plastids arose when a heterotrophic protist acquired a cyanobacterial endosymbiont The photosynthetic descendants of this ancient protist evolved into red algae and green algae Land plants are descended from the green algae Archaeplastida is the supergroup that includes red algae, green algae, and land plants |
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Illustrate the divergences of red algae, green algae, and land plants.
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Describe the unique characteristics of red algae.
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Red Algae Red algae are reddish in color due to an accessory pigment called phycoerythrin, which masks the green of chlorophyll The color varies from greenish-red in shallow water to dark red or almost black in deep water Red algae are usually multicellular; the largest are seaweeds Red algae are the most abundant large algae in coastal waters of the tropics |
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Give three examples of red algae.
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What are green algae?
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Green Algae Green algae are named for their grass-green chloroplasts Plants are descended from the green algae Green algae are a paraphyletic group The two main groups are the charophytes and the chlorophytes Charophytes are most closely related to land plants |
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Describe the increasing complexity of chlorophytes.
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Larger size and greater complexity evolved in chlorophytes by The formation of colonies from individual cells The formation of true multicellular bodies by cell division and differentiation (e.g., Ulva) The repeated division of nuclei with no cytoplasmic division (e.g., Caulerpa) |
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Give two examples of Green Algae
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What type of life cycles do most chlorophytes possess?
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Most chlorophytes have complex life cycles with both sexual and asexual reproductive stages
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Illustrate the complex life cycle of the Chlorophyte, with both sexual and asexual reproductive stages.
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Describe the supergroup Unikonta and what it includes.
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Concept 28.5: Unikonts include protists that are closely related to fungi and animals The supergroup Unikonta includes animals, fungi, and some protists This group includes two clades: the amoebozoans and the opisthokonts (animals, fungi, and related protists) The root of the eukaryotic tree remains controversial It is unclear whether unikonts separated from other eukaryotes relatively early or late |
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Illustrate the questionable phylogeny of Unikonta.
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What characterizes ameobozoans?
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Amoebozoans Amoebozoans are amoeba that have lobe- or tube-shaped, rather than threadlike, pseudopodia They include slime molds, tubulinids, and entamoebas |
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What characterizes slime molds?
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Slime Molds Slime molds, or mycetozoans, were once thought to be fungi DNA sequence analyses indicate that the resemblance between slime molds and fungi is a result of convergent evolution Slime molds include two lineages, plasmodial slime molds and cellular slime molds |
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Describe the coloration of Plasmodial slime molds.
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Plasmodial Slime Molds Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange |
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Illustrate the life cycle of Plasmodial slime molds.
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Describe the formation of the plasmoidum mass in the plasmodial slime molds' life cycle.
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At one point in the life cycle, plasmodial slime molds form a mass called a plasmodium (not to be confused with malarial Plasmodium) The plasmodium is not multicellular It is undivided by plasma membranes and contains many diploid nuclei It extends pseudopodia through decomposing material, engulfing food by phagocytosis |
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What characterizes cellular slime molds?
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Cellular Slime Molds Cellular slime molds form multicellular aggregates in which cells are separated by their membranes Cells feed individually but can aggregate to migrate and form a fruiting body Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity |
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Illustrate the life cycle of cellular slime molds.
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What characterizes Tubulinids?
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Tubulinids Tubulinids are a diverse group of amoebozoans with lobe- or tube-shaped pseudopodia They are common unicellular protists in soil as well as freshwater and marine environments Most tubulinids are heterotrophic and actively seek and consume bacteria and other protists |
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What characterizes Entamoebas?
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Entamoebas Entamoebas are parasites of vertebrates and some invertebrates Entamoeba histolytica causes amebic dysentery, the third-leading cause of human death due to eukaryotic parasites |
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What characterizes Opisthokonts?
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Opisthokonts Opisthokonts include animals, fungi, and several groups of protists |
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Where are protists found and what roles do they play in their habitats?
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Concept 28.6: Protists play key roles in ecological communities Protists are found in diverse aquatic and moist terrestrial environments Protists play two key roles in their habitats: that of symbiont and that of producer |
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What characterizes Symbiotic protists?
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Symbiotic Protists Some protist symbionts benefit their hosts Dinoflagellates nourish coral polyps that build reefs Wood-digesting protists inhabit the gut of termites |
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Describe examples of parasitic protists.
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Some protists are parasitic Plasmodium causes malaria Pfiesteria shumwayae is a dinoflagellate that causes fish kills Phytophthora ramorum causes sudden oak death P. infestans causes potato late blight, which contributed to the Irish famine of the 19th century |
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What characterizes photosynthetic protists?
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Photosynthetic Protists Many protists are important producers that obtain energy from the sun In aquatic environments, photosynthetic protists and prokaryotes are the main producers In aquatic environments, photosynthetic protists are limited by nutrients These populations can explode when limiting nutrients are added |
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What kind of effect has sea surface temperature had on photosynthetic protist biomass?
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Biomass of photosynthetic protists has declined as sea surface temperature has increased Growth of phytoplankton communities relies on nutrients delivered from the ocean bottom through the process of upwelling Warm surface water acts as a barrier to upwelling |
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What three things could continued warming of sea surface temperature have large effects on?
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If sea surface temperature continues to warm due to global warming, this could have large effects on: 1. Marine ecosystems 2. Fishery yields 3. The global carbon cycle |
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Illustrate basic sea surface temperatures across the globe.
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What characterizes the classification of protists?
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Living Small Even a low-power microscope can reveal a great variety of organisms in a drop of pond water Protist is the informal name of the group of mostly unicellular eukaryotes Advances in eukaryotic systematics have caused the classification of protists to change significantly Protists constitute a polyphyletic group, and Protista is no longer valid as a kingdom |
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Illustrate a phylogeny, beginning with the last common ancestor of Excavata, SAR clade, Archaeplastida, and Unikonta.
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Illustrate the general divergence of Excavata.
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What are the 5 domains of life?
Where did they diverge from? |
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