Unit 5

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Prokaryotes

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An organism of the kingdom Monera (or Prokaryotae), comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes. Also called moneran.

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bacteria

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ubiquitous one-celled organisms, spherical, spiral, or rod-shaped and appearing singly or in chains, comprising the Schizomycota, a phylum of the kingdom Monera (in some classification systems the plant class Schizomycetes), various species of which are involved in fermentation, putrefaction, infectious diseases, or nitrogen fixation

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spirochetes

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Any of various slender, spiral, motile bacteria of the order Spirochaetales, many of which are pathogenic, causing syphilis, relapsing fever, yaws, and other diseases.

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Monera

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a taxonomic kingdom of prokaryotic organisms that typically reproduce by asexual budding or fission and have a nutritional mode of absorption, photosynthesis, or chemosynthesis, comprising the bacteria, blue-green algae, and various primitive pathogens.

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thermopiles

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A device consisting of a number of thermocouples connected in series or parallel, used for measuring temperature or generating current.

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Eukaryotes

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. A single-celled or multicellular organism whose cells contain a distinct membrane-bound nucleus.

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Protists

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A unicellular protoctist in taxonomic systems in which the protoctists are considered to form a kingdom.

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Algae

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any of numerous groups of chlorophyll-containing, mainly aquatic eukaryotic organisms ranging from microscopic single-celled forms to multicellular forms 100 ft. (30 m) or more long, distinguished from plants by the absence of true roots, stems, and leaves and by a lack of nonreproductive cells in the reproductive structures: classified into the six phyla Euglenophyta, Crysophyta, Pyrrophyta, Chlorophyta, Phaeophyta, and Rhodophyta.

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Bryophytes

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A member of a large group of seedless green plants including the mosses, liverworts, and hornworts. Bryophytes lack the specialized tissues xylem and phloem that circulate water and dissolved nutrients in the vascular plants. Bryophytes generally live on land but are mostly found in moist environments, for they have free-swimming sperm that require water for transport. In contrast to the vascular plants, the gametophyte (haploid) generation of bryophytes constitutes the larger plant form, while the small sporophyte (diploid) generation grows on or within the gametophyte and depends upon it for nutrition.

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Ferns

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Any of numerous flowerless, seedless vascular plants having roots, stems, and fronds and reproducing by spores.

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Gymnosperm

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a vascular plant having seeds that are not enclosed in an ovary; a conifer or cycad.

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Angiosperm

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a plant having its seeds enclosed in an ovary; a flowering plant.

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Porifera

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an animal phylum comprising the sponges.

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Sponges

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Porous plastics, rubber, cellulose, or other material, similar in absorbency to this skeleton and used for the same purposes.

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Radials

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Having or characterized by parts so arranged or so radiating.

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Cnidarians

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Any of various invertebrate animals of the phylum Cnidaria, characterized by a radially symmetrical body with a saclike internal cavity, and including the jellyfishes, hydras, sea anemones, and corals. Also called coelenterate.

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Gastro vascular

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Having the structure, or performing the functions, both of digestive and circulatory organs; as, the gastrovascular cavity of lenterates

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Bilateral

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Having two sides or pertaining to both sides

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Protostome

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Any of a major group of animals defined by its embryonic development, in which the first opening in the embryo becomes the mouth. At this stage of development, the later specialization of any given embryonic cell has already been determined. Protostomes are one of the two groups of animals having a true body cavity (coelom) and are believed to share a common ancestor. They include the mollusks, annelids, and arthropods.

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Flatworms

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Any of various parasitic and nonparasitic worms of the phylum Platyhelminthes, characteristically having a soft, flat, bilaterally symmetrical body. Flatworms lack a coelom (body cavity), respiratory system, and circulatory system, but are the most primitive invertebrates to have a brain. The evolutionary history of flatworms is uncertain, but they share some basic characteristics with rotifers, nematodes, and a few other invertebrate phyla. Cestodes (tapeworms), planarians, and trematodes (flukes) are flatworms

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Annelids

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Any of various worms or wormlike animals of the phylum Annelida, characterized by an elongated, cylindrical body divided into ringlike segments. Most annelids have movable bristles called setae, and include earthworms, leeches, and polychetes (marine worms).

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Mollusks

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Any of numerous chiefly marine invertebrates of the phylum Mollusca, typically having a soft unsegmented body, a mantle, and a protective calcareous shell and including the edible shellfish and the snails.

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Brachiopods

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Any of various marine invertebrate animals of the phylum Brachiopoda that resemble clams. Brachiopods have paired upper and lower shells attached to a usually stationary stalk and hollow tentacles covered with cilia that sweep food particles into the mouth. Brachiopods are probably related to the phoronids and bryozoans, and were extremely abundant throughout the Paleozoic Era.

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Arthropods

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Any of numerous invertebrate animals of the phylum Arthopoda, characterized by an exoskeleton made of chitin and a segmented body with pairs of jointed appendages. Arthropods share many features with annelids and may have evolved from them in the Precambrian Era. Arthropods include the insects, crustaceans, arachnids, myriapods, and extinct trilobites, and are the largest phylum in the animal kingdom.

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Nematodes

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Any of several slender, cylindrical worms of the group Nematoda, which some scientists consider to be a class of the aschelminths and others to be a separate phylum. Most nematodes are tiny and live in enormous numbers in water, soil, plants, and animals. They have a simple structure, with a long hollow gut separated from the body wall by a fluid-filled space. Several nematodes, such as pinworm, roundworm, filaria, and hookworm, are parasites on animals and humans and cause disease. One species, Caenorhabditis elegans (usually called C. elegans), was one of the first animals to have its entire genome sequenced and is important in biological research as a model organism.

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Invertebrates

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An animal that has no backbone or spinal column and therefore does not belong to the subphylum Vertebrata of the phylum Chordata. Most animals are invertebrates. Corals, insects, worms, jellyfish, starfish, and snails are invertebrates

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Echinoderms

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Any of various marine invertebrates of the phylum Echinodermata, having a latticelike internal skeleton composed of calcite and usually a hard, spiny outer covering. The body plans of adult echinoderms show radial symmetry, typically in the pattern of a five-pointed star, while the larvae show bilateral symmetry. Echinoderms probably share a common ancestor with the hemichordates and chordates, and were already quite diversified by the Cambrian Era. They include the starfish, sea urchins, sand dollars, holothurians (sea cucumbers), and crinoids, as well as thousands of extinct forms.

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coelomes

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The cavity within the body of all animals higher than the coelenterates and certain primitive worms, formed by the splitting of the embryonic mesoderm into two layers. In mammals it forms the peritoneal, pleural, and pericardial cavities

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Pseudocoelomate

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have a pseudocoel (literally “false cavity”). Tissue derived from mesoderm only partly lines the fluid filled body cavity of these animals. Thus, although organs are held in place loosely, they are not as well organized as in a coelomate. All pseudocoelomates are protostomes; however, not all protostomes are pseudocoelomates. Also referred to as Hemocoel and Blastocoelomate.