The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
All plants and animals require certain chemicals for growth and survival. These chemicals are called biogenic salts or nutrients (from the Latin word nutrio meaning to feed, rear, or nourish). They can be categorized as those needed in large amounts called macronutrients, and those needed in minute amounts called micronutrients or trace elements. Macronutrients include nitrogen (an essential building block of chlorophyll and protein), phosphorus (used to make DNA and ATP), calcium (a component of cell walls and bones), sulfur (a component of amino acids), and magnesium (a component of bones and chlorophyll). Micronutrients, although needed only in trace amounts, are still essential for survival. Examples include cobalt (used in the synthesis of vitamin B12), iron (essential for photosynthesis and blood respiratory pigment), and sodium (used in the maintenance of proper acid-based balance called osmoregulation, nerve transmission, and several other functions). Some micronutrients, such as copper and zinc, can be harmful in large amounts. The borderline between necessary and excessive is often narrow and varies among species.