The Elements of Life (Campbell Biology)
Of the 92 natural elements, about 20–25% are essential elements that an organism needs to live a healthy life and reproduce. The essential elements are similar among organisms, but there is some variation—for example, humans need 25 elements, but plants need only 17.
Just four elements—oxygen (O), carbon (C), hydrogen (H), and nitrogen (N)—make up approximately 96% of living matter. Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), and a few other elements account for most of the remaining 4% or so of an organism’s mass. Trace elements are required by an organism in only minute quantities. Some trace elements, such as iron (Fe), are needed by all forms of life; others are required only by certain species. For example, in vertebrates (animals with backbones), the element iodine (I) is an essential ingredient of a hormone produced by the thyroid gland. A daily intake of only 0.15 milligram (mg) of iodine is adequate for normal activity of the human thyroid. An iodine deficiency in the diet causes the thyroid gland to grow to abnormal size, a condition called goiter. Consuming seafood or iodized salt reduces the incidence of goiter. Relative amounts of all the elements in the human body are listed in Table 2.1.
Some naturally occurring elements are toxic to organisms. In humans, for instance, the element arsenic has been linked to numerous diseases and can be lethal. In some areas of the world, arsenic occurs naturally and can make its way into the groundwater. As a result of using water from drilled wells in southern Asia, millions of people have been inadvertently exposed to arsenic-laden water. Efforts are under way to reduce arsenic levels in their water supply.
Urry, Lisa A.. Campbell Biology. Pearson Education. Kindle Edition. https://www.pearson.com/us/higher-education/series/Campbell-Biology-Series/2244849.html
Date Published: December 23, 2015 Publisher: Public Library of Science Author(s): Debra Trampe, Jordi Quoidbach, Maxime Taquet, Alessio Avenanti. http://doi.org/10.1371/journal.pone.0145450 Abstract: Despite decades of research establishing the causes and consequences of emotions in the laboratory, we know surprisingly little about emotions in everyday life. We developed a smartphone application that monitored real-time emotions of an … Continue reading
Date Published: April 14, 2016 Publisher: Public Library of Science Author(s): W. Ford Doolittle, Tyler D. P. Brunet, Susan M. Rosenberg Abstract: A universal Tree of Life (TOL) has long been a goal of molecular phylogeneticists, but reticulation at the level of genes and possibly at the levels of cells and species renders any simple … Continue reading
Date Published: June 23, 2006 Publisher: Public Library of Science Author(s): Morgan N Price, Adam P Arkin, Eric J Alm, Ivan Matic Abstract: Operons are a major feature of all prokaryotic genomes, but how and why operon structures vary is not well understood. To elucidate the life-cycle of operons, we compared gene order between Escherichia … Continue reading
Date Published: November 14, 2006 Publisher: Public Library of Science Author(s): Antonis Rokas, Sean B Carroll Abstract: A discussion of how homoplasy (the frequency of independently evolved characters) and the spacing of cladogenetic events limit our ability to reconstruct the tree of life using existing phylogenetic methods. Partial Text: Genome analyses are delivering unprecedented amounts … Continue reading
Date Published: November 4, 2014 Publisher: Public Library of Science Author(s): Kalie Sacco, John H. Falk, James Bell Abstract: Informal Science Education: Lifelong, Life-Wide, Life-Deep Informal science education cultivates diverse opportunities for lifelong learning outside of formal K-16 classroom settings, from museums to online media, often with the help of practicing scientists. Partial Text: The … Continue reading