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¶ … Environment Influences the Body Plan of Organisms
The distinction between Radiata and Bilateria, or organisms with a radial or bilateral symmetry, is that the latter have a dorsal/ventral polarity resulting in bilateral body axes (reviewed by Martindale and Henry, 1998). By comparison, species with radial symmetry, the Radiata, have a single anterior/posterior axis in their body plan and no dorsal/ventral polarity. Another general distinction is the presence of three germ layers in the Bilateria, which are the endoderm, ectoderm, and mesoderm. These three pluripotent cell types will give rise to organs and internal epithelial layers, skin and nervous tissues, and muscle and connective tissues, respectively.
Role of Environment
Radiata contain a digestive tract that is perpendicular to radial structures (reviewed by Martindale and Henry, 1998). For example, the cnidarians have a mouth that is surrounded by radial pattern of tentacles. After the food enters the mouth, it collects in a gastric cavity shaped like a bowl. The Radiata ctenophores have a complete digestive system...
The evolution of Bilateria is believed to represent a less passive method for finding food, one that depends on a nervous system capable of sensing and reacting to environmental cues through motor commands (reviewed by Yoshimura and Motokawa, 2010). Bilateria are therefore capable of actively moving toward food sources, whereas Radiata are generally forced to wait for the food to come within range of their tentacles. The evolution of bilateral symmetry has allowed exploitation of environmental niches normally out of reach for organisms with a radial symmetry.
Case Study in Bilateral Symmetry Evolution
Sea urchins are members of Radiata; however, sea urchins with bilateral symmetry have emerged at least twice during evolutionary history (reviewed by Yoshimura and Motokawa, 2010). The bilateral…
References
Martindale, Mark Q. And Henry, Jonathan Q. (1998). The development of radial and biradial symmetry: The evolution of bilaterality. American Zoologist, 38, 672-684.
Yoshimura, Kazuya and Motokawa, Tatsuo. (2010). Bilaterality in the regular sea urchin Anthocidaris crassispina is related to efficient defense not to efficient locomotion. Marine Biology, 157, 2475-2488.
Of the top 150 medications that are sold by prescription in the U.S. 118 of these are medications that are either "derived from or modeled on naturally occurring substances." (SEAM Global, 2005) Some of the medications that count on habitat presently being destroyed are "aspirin, morphine, vincristine, taxol, digitalis, and most antibiotics."(SEAM Global, 2005) VI. Internet/Networking: Role Played in Preservation Through global and subglobal assessments of the ecosystem and monitoring of
Formation Organizations Factors Influencing the Formation of the Organizations Organization formation is a tentative figure that has led to the establishment of many human interactive features in the world. There are different approaches through which organization formation takes place. The developmental strategies that led to the establishment if the present societies is accrued to the fact that the existence of the societal structures is a basic feature that promotes organizational formation.
Technology Learning Environ New technology has become an integral part of the learning environment, and not just an adjunct to it. This article demonstrates the limitations of using technology in the educational profession. First, technology depends on human input and guidance in order to be properly and relevantly developed. Second, technology must be fully integrated with the learning environment; it can't and shouldn't float on top of it. Rather, technology needs
This can contribute directly to human health and development (AgBio). Borlaug (1999), who won the Nobel Prize in 1970 for his work in developing high-yield wheat and other grains in third-world countries, stresses that genetic engineering is essential due to the worldwide population growth. Other organizations supporting genetically modified foods are the American Medical Association, the International Association of African Scientists, the Organization for Economic Cooperation and Development, and
Wound Care Chronic wounds represent a devastating health care problem with significant clinical, physical and social implications. Evidence suggests that consistent, meticulous and skilled care provides the primary means by which successful wound care and healing is promoted. The occurrence of wounds has plagued humankind throughout recorded history and remains a major source of morbidity and mortality in several disciplines of clinical medicine. Within this thesis, an effort will be made
Huntington's disease (HD) was the first autonomic dominant disorder for which genetic prediction became possible" (Harper, et al., 2000, Journal of Medical Genetics, p. 567). HD is a disease that occurs due to an inherited disorder leading to the death of brain cells. A diagnosis of HD is accomplished through genetic testing which can be implemented at any age regardless of whether the symptoms manifest or not. Although, the specific