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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A division (also known as Hemimetabola) of the subclass Pterygota, including those insects that show relatively slight change in body form with growth. They develop through a series of immature forms (nymphs) from hatchling to adult, so that wings grow as external pads and enlarge with each molt. The nymphs are often scaled-down copies of the adults, but in some cases, particularly in those orders with aquatic nymphs and aerial-terrestrial adults (such as in Ephemeroptera and Odonata), a considerable difference in body form exists between adults and their immature forms. This development, called incomplete metamorphosis, is characteristic of all Paleoptera and some members of the infraclass Neoptera (all ancestrally winged insects except Endopterygota). Most exopterygotan taxa have freely mobile nymphs with well-developed legs, although conspicuous exceptions occur in the form of the scale insects (Coccoidea) and some of their highly sedentary sap-feeding allies.
Industry:Science
A division (also known as Holometabola) of the subclass Pterygota, including those insects that undergo complete metamorphosis during their life cycle. That is, individual development goes through four distinct stages: egg, larva (trophic), pupa (reconstructive), and adult (reproductive). The larval and adult stages often live in very different adaptive zones and have very different life forms, necessitating a quiescent pupal stage in which extensive restructuring takes place. Typically growing through a sequence of immature forms (instars) punctuated by integumental molts, the larval instars correspond to those of nymphal Exopterygota in most ways, but are distinct in having wings, internalized as tiny wing buds. The buds are tucked out of the way of the larva, grow very rapidly in the pupal stage, and expand and quickly become functional in the newly hatched adult.
Industry:Science
A division of seed plants consisting of about 250,000 species, which form the bulk and most conspicuous element of the land plants. Often called flowering plants or angiosperms, they have several unique characteristics, the most prominent of which are their reproductive structure, flowers, and covered seeds. The other obvious woody land plants are the gymnosperms, which have cones instead of flowers and have naked seeds. Another trait distinguishing the angiosperms is the presence of double fertilization, which results in the production of stored food (starch or oils) within their seeds.
Industry:Science
A division of the animal kingdom sometimes ranked as intermediate between the Protozoa and the Metazoa. These animals are unassignable to any of the better-known phyla, as usually defined. In the absence of proof concerning their relationships, and in view of the disagreement among zoologists relative to their affinities and even with respect to the facts and interpretation of their structure and life cycle, they are treated as a small phylum somewhere between Protozoa and Platyhelminthes. No particular phylogenetic interpretation should be attached to this placement.
Industry:Science
A division of the Echinodermata made up of those forms which are anchored to the substrate during at least a part of the life history. Formerly treated as a formal unit of classification with the rank of subphylum, pelmatozoans are now realized to be a heterogeneous assemblage of forms with similar habits but dissimilar ancestry, their common features having arisen by convergent evolution. Most pelmatozoan echinoderms are members of the subphylum Crinozoa, but some echinozoans also exhibit a sedentary, anchored life, with modifications for such existence.
Industry:Science
A division of the plant kingdom (also known as Chlorophyta or Chlorophycophyta) comprising all algae that have chlorophyll <i>a</i> and <i>b</i> except the Euglenophyceae, and that in all other respects are so different as to suggest a separate origin of their photosynthetic pigments. Three classes, Charophyceae (charophytes), Chlorophyceae (green algae), and Prasinophyceae, are recognized.
Industry:Science
A division of the plant kingdom (also known as Chromophyta) comprising nine classes of algae: Bacillariophyceae (diatoms), Chrysophyceae (golden or golden-brown algae), Cryptophyceae, Dinophyceae (dinoflagellates), Eustigmatophyceae, Phaeophyceae (brown algae), Prymnesiophyceae, Raphidophyceae, and Xanthophyceae (yellow-green algae). Some of these classes are closely related, while others stand so far apart that they are sometimes assigned to their own divisions. The chief unifying character is the presence of chlorophyll <i>c</i> rather than chlorophyll <i>b</i> as a complement to chlorophyll <i>a</i> (although only chlorophyll <i>a</i> is present in Eustigmatophyceae). The chloroplasts are usually brown or yellowish because of large amounts of β-carotene and various xanthophylls, many of which are restricted to one or more classes. Storage products include lipids, starch, and glucans (glucose polymers with β-1,3 linkages). In all classes except Dinophyceae, the chloroplast is surrounded by chloroplast endoplasmic reticulum that is continuous with the nuclear envelope, and the deoxyribonucleic acid of the chloroplast forms an annular genophore. Except in Cryptophyceae, thylakoids are in groups of three. In most classes, motile cells bear two unequal flagella, one of which may be almost completely reduced and at least one of which bears two rows of hairlike appendages. Algae in this division range in size and complexity from unicellular flagellates to gigantic kelps.
Industry:Science
A division of the plant kingdom consisting of only two genera with three living species, <i>Psilotum nudum</i>, <i>P. complanatum</i>, and <i>Tmesipteris tannensis</i>. <i>Psilotum</i> is widespread in tropical and subtropical regions of both hemispheres, but <i>Tmesipteris</i> is confined to Australia and some of the Pacific islands.
Industry:Science
A division of the plant kingdom, commonly called the ferns, which is widely distributed throughout the world but is most abundant and varied in moist, tropical regions. The Polypodiophyta are sometimes treated as a class Polypodiopsida of a broadly defined division Tracheophyta (vascular plants). The group consists of five living orders (Ophioglossales, Marattiales, Polypodiales, Marsileales, and Salviniales), plus several orders represented only by Paleozoic fossils. The vast majority of the nearly 10,000 species belong to the single order Polypodiales, sometimes also called Filicales.
Industry:Science
A division that consists of some 23,000 species of small and relatively simple plants commonly known as mosses, granite mosses, peat mosses, liverworts, and hornworts (see <b>illus.</b>). The bryophytes display a distinct alternation of sexual and asexual generations; the sexual gametophyte, with a haploid chromosome number, is the more diversified. The sporebearing, diploid sporophyte is reduced in size and structure, attached to the gametophyte, and partially or almost completely dependent on it.
Industry:Science
