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Eubacteria (Bacteria): true bacteria, cyanobacteria, spirochetes, purple and green bacteria, pathogens
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Prokaryotes; the most metabolically diverse—organisms: autotrophs (photosynthetic and chemosynthetic), hetertophs; anaerobes, and aerobes
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The most abundant, smallest, and oldest organisms; present 2 billion years before eukaryotes appeared; modified the environment and made possible eukaryotic life
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Recycle organic matter; fix atmospheric nitrogen; significant cause of diseases; used in industry to make cheese, alcohol, antibiotics, and in genetic engineering
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Archaebacteria: extremophiles, methanogens, halophiles, thermophiles
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Prokaryotes of extreme environments, i.e. very: hot, cold, acid, salty; structurally different from eubacteria and more closely related to the eukaryotes; appeared later than eubacteria
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The endosymbiosis theory suggests some prokaryotes were engulfed by others and lived symbiotically within them; over time, these became the organelles of eukaryote cells
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Extremophiles responsible for: natural gas reserves, colors in hot-springs, salt flats; live in hydrothermal vents on the ocean floor in high pressures and temperatures
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Viruses (Not Organisms): bacteriophage, retrovirus, HIV, polio virus, tobacco mosaic cell; virus, rhinovirus, Ebola virus
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Non-cellular, not alive; are molecules of DNA or RNA surrounded by like their own, need specific protein; need energy from a host cell to replicate; non-motile; don't grow nor metabolize
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No fossil record; may have caused malformations seen in some fossils of early organisms; probably arose as bits of DNA broken from genomes of cells
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Attack hosts with genomes most protein receptors to enter a presence triggers response, i.e. disease in plants, animals, bacteria, protists
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Fungi: mushrooms, truffles, rusts, smuts, molds, yeasts, rots. Divided into four or five groups on basis of their sexual reproductive structures: Zygomycota, Ascomycota, Basidiomycota, Deuteromycetes, Fungi Imperfecti. Chytridiomycota often included with Fungi
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Not plants; eukaryotic body called mycelium consists of masses of hyphae (filaments); cell walls of chitin; glycogen stored as reserve food; are heterotrophic; obtain food by spores and sexually by zygotic meiosis
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Oldest filaments appear in a Lower Cambrian; also some mycorrhizae in stems of an early Devonian plant; mycorrhizae may have facilitated the move of plants from water to land—with fungi substituting for roots of the first land plants
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The principal decomposers together with the bacteria; most are saprotrophs (saprobes); some are causal agents of plant, animal, human diseases; many form important symbioses with roots of vascular plants (mycorrhizae); others are symbiotic with algae forming
lichens; some edible, others used commercially in brewing, baking, medicine
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Protista (Protoctista): algae, amoebae, flagellates, sporozoans, ciliates, water molds, diatoms, slime molds, etc. No completely satisfactory way to classify this extremely diverse group
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Not plants; eukaryotes many with plant-like features (chlorophyll, photosynthetic, cellulose in walls), others like fungi (filamentous), some animal-like (ingest food); unicellular, multicellular, colonial; mostly aquatic, both marine and freshwater
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Oldest eukaryote may be a brown-alga-like fossil 1.7 billion years old; or another presumed photosynthetic eukaryote found in 2.1-billion-year-old rocks; acritarchs (fossilized shells of shelled amoebas) first found in rocks 1.5 billion years old
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Importantance: plants, animals, and fungi all derived from ancient protists; plant ancestor a green alga very much like green algae of today
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Plantae– Bryophytes: mosses, liverworts, hornworts. Divided into three groups: Bryophyta (mosses), Hepaticophyta (liverworts), Anthocerotophyta (hornworts)
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Small, nonvascular plants; body a thallus; gametophyte is free-living and the prominent plant; the sporophyte small, dependent upon the gametophyte; both sexual and asexual reproduction present; motile (flagellated) sperm require water in which to reach the egg
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Ancestors of bryophytes probably derived from a green alga ancestor; oldest fossil bryophytes in 350 million years old rocks (younger than first vascular plant fossils, but probably because bryophytes lack resistant tissues for preservation)
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Three groups are of different lineages, liverworts the oldest; mosses important in the ecology of the arctic and subarctic; some commercial use—peat for fuel,
Sphagnum as packing material
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Plantae–Seedless Vascular Plants: ferns, fern allies, and horsetails. Divided into four groups: Psilotophyta (whisk ferns), Lycophyta (club mosses), Sphenopsida (horsetails), Pterophyta (ferns)
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Xylem and phloem present; sporophyte dominant; asexual spores produced in sporangia; some taxa homosporous, others heterosporous
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Earliest vascular plants were small, simple, and dominated mid-Silurian to mid-Devonian landscapes (425–370 million years ago); by late Devonian through the Carboniferous (the Coal Age), plants formed swamp forests of large trees; major groups died out by end of the Permian (250 million years ago)
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Most living taxa are depauperate remnants of large tree species of the Coal Age flora
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Plantae–Gymnosperms: conifers, cycads, gnetophytes, pines, junipers, yews, sequoia; divided into four groups: Cycadophyta (cycads), Ginkgophyta (
Ginkgo), Coniferophyta (conifers), and Gnetophyta (gnetophytes)
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Ovules and seeds exposed and not covered by sporophyte tissue at time of pollination; wood lacks fibers and contains only tracheids (except in gnetophytes, which have vessels in addition); some have flagellated sperm carried in a pollen tube toovule; female gametophyte produces several archegonia and embryos, but usually only one embryo survives/ovule
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Seed plants probably evolved from seed-bearing progymno-sperms sometime during the Devonian (370 million years ago); current gymnosperms represent a series of separate lineages
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Trees and shrubs with no herbaceous representatives (some vine-like
Gnetum species are present); distributed world-wide from boreal conifer forests to tropics, some taxa mixed with Angiosperm trees, others in pure stands of Gymnosperms
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Plantae–Anthophyta: angiosperms, flowering plants
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Ovules enclosed in a carpel and seeds produced in fruits; both gemetophytes highly reduced (female a seven-celled structure, male the germinated pollen grain); sporophyte the dominant plant
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First fossil flowers appear in Cretaceous beds 130 million years old; in next 35 million years (Upper Cretaceous), angiosperms spread and became dominant plants in the Northern Hemisphere and, in next 10 million years, in the Southern Hemisphere also
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Most successful of all the plant groups; insect-pollinated flowers basic; seeds with embryos enclosed in a resistant seed coat enabled plants to be widely dispersed; physiological adaptations and production of secondary metabolites of importance in their success
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Themes of Plant Biology
A Synopsis of the Living World
