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Diversity of Life Quiz: Protists and Fungi

Chapter 29: Protists

Protists in a Large-Scale Perspective:

Paraphyletic grouping (do not share derived characteristics that set them apartfrom all other lineages on the tree of life).

Are a paraphyletic groupthey represent some, but not all, of the descendantsof a single common ancestor.

Morphological diversity over time: nuclear envelope, multicellularity, variedsupport and protection structures, forms of sexual reproduction andmulticellularity

Mitochondrion and chloroplast arose by endosymbiosis

Origin of nuclear envelope and ER: infolding of plasma membrane

The endosymbiosis theory proposes that mitochondria originated when abacterial cell took up residence inside a eukaryote about 2 billion years ago.

Steps of the endosymbiosis theory:1. Eukaryotic cell engulfs bacterium2. Bacterium survives3. Endosymbiosis: Both benefit from higher mitochondrial ATP yield

Secondary endosymbiosis occurs when an organism engulfs a photosyntheticeukaryotic cell and retains its chloroplasts as intracellular symbionts.

Symbiosis occurs when individuals of two different species live in physicalcontact.

Endosymbiosis occurs when an organism of one species lives inside anorganism of another species.

Can produce sexually and asexually: fertilizationthe fusion of two gametes toform a diploid zygote

Sporophytes: produces spores via meiosisGameophytes: produce gametes via mitosis

Common feature: often live in environments surrounded by water

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How do protists move? Amoeboid motion (sliding movement via pseudopodia),locomotion, cilia, flagella

Protists vary in terms of how they find food. Some are photosynthetic, othersingest food packets, others absorb food from their environments

Feeding by engulfing is possible in protists that lack a cell wall.A flexible membrane and dynamic cytoskeleton give these species theability to surround and swallow prey with long, fingerlike projections calledpseudopodia.

Some protists also feed by sweeping food particles into their mouth withcilia.

Absorptive feeding: nutrients are taken up directly from the environment,across the plasma membrane.

Could Protists fix global warming?

Yes; protists act as carbon sinks that could help reduce global warming.A carbon sink is a long-lived carbon reservoir. Carbon sinks produced by protistscan be either:

Sedimentary rocks.Petroleum.

Microscopy: a method used to study cell structures in protists; allows researchersto identify characteristics of specific lineages. These characteristic classes arecalled Synapomorphiesshared, derived traits that are used to distinguishmajor monophyletic groups.

7 Eukaryotic Lineages ex: PlantaeMolecular phylogenies in protists have come about b/c of change over time (ex:bikonta (2 flagellum) and unikonta (1 flagella)

Species of Protists:

Stramenopila (Heterokonta): Flagella with distinctive hollow hairs

Species: Distinguishing Factors:Oomycota Water molds

Absorb nutrition from living or deadhostsDecomposers in aquatic ecosystemsCaused Irish potato famine

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Diatoms Glass-like cell wall!Live near surface of waterways thatdrift/swim short distances (plankton)Plankton in cold, nutrient-rich waters**most important producer of carbon

compounds in the water**

phytoplankton -- base of aquatic foodchain**

Phaeophyta Brown algae; lives in marine habitatsBlade, stipe, holdfast

Alveolata: small sacs, alvaeoli (located under plasma membranes) that stiffen thecell!!

Species: Distinguishing Factors:

Ciliata Locomotion12,000 speciesLive in guts of grazing animalsmutualisticallyEx: paramecium

Dinoflagellata Cell wall made up of cellulose plates!

Ocean-dwelling planktonBIOLUMINESCENCEToxin-producing protists

Can cause RED TIDES: when d.f.reach high densities in an aquaticenvironment

Red tides can be harmful to humansbecause these toxins build up inshellfish, which humans consume, andpoisoning can result

Apicomplexa All parasiticMalaria-causing (worlds most chronichealth problem)

Rhizaria: single-celled amoebae, lack cell walls, make shells, pseudopodia

Species: Distinguishing Factors:Foraminifera Shell form chalk, limestone, etc.

Calcium carbonate shell or cover inpebbles!

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Plantae: red algae, green algae, land plants, etc.

Species: Distinguishing Factors:Rodophyta Red algae

6,000 species

Live in DEEP water

Excavata: excavated feeding groove found on one side of the cell; lackmitochondria

Species: Distinguishing Factors:Parabasalida unique internal support rods!!

Live in animalsEx: disease-causing Trichomonas

Diplomonadida Live in low-oxygen environmentsStagnant water env.

Euglenida **protein strips under plasmamembrane!!**FreshwaterCarb: paramylon

Amoebozoa: lack cell walls and take in food by engulfing it, produce large lobe-like pseudopodia, ex: slime molds

Species: Distinguishing Factors:Myxogastrida Plasmodial Slime Mold

supercell

Decomposers in forest ecosystems

Chapter 31: Fungi

Fungi in a Large-Scale Perspective:

Mostly multicellular euaryotes

Benefits of Fungi:Many live in close association with land plants. They supply plants with key

nutrients and decompose dead wood. They are the master recyclers of nutrientsin terrestrial environments. The roots of virtually every land plant are colonized bymutualistic fungi. In exchange for sugars synthesized by the plant, the fungiprovide the plant with water and key nutrients without which the host plants growmore slowly or even starve.

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Because they recycle key elements such as carbon, nitrogen, and phosphorusand because they transfer key nutrients to plants, fungi have a profoundinfluence on productivity and biodiversity.

Source of many antibiotics, source of yeast, which has aided human food

production

Mycorrhizal associations between fungi and plant roots allow faster plantgrowth.

Saprophytes are fungi that make their living by digesting dead plant material.

How does Fungi speed the Carbon cycle on land?

The carboncycle on land has two basic components:1.The fixation of carbon by land plants.

2.The release of CO2 from plants, animals, and fungi as the result of cellularrespiration.

For most carbon atoms, fungi connect the two components, as they are theorganisms that break down the complex molecules in wood into reusable organiccompounds.

How Fungi Feed:Absorb nutrients from living or dead organisms. Fungi secrete enzymes so thatdigestion takes place outside their cells. Their morphology provides a largeamount of surface area for efficient absorption.

unique ability to absorb the cellulose and lignin that comprise wood

How Fungi Reproduce:It is common for species to have a long-lived heterokaryotic stage, in which cellscontain haploid nuclei from two different individuals.