A comparative review of the vascular system in seed plants and humans
In the evolutionary tree of life, all biotic organisms are believed to have derived from a common ancestor. The organisms falling under the eukaryotic kingdom of Plantae are known to have arisen in the same time period as those in the eukaryotic kingdom of Animalia—the Paleozoic era, about 500 million years ago (MYA) (Raven et al., 2008). Despite their chronological resemblance, their evolutionary diversity is especially great in their most advanced organisms—humans and seed plants. One key system that illustrates this diversity is the vascular system (or the cardiovascular system in humans). The vascular system of the respective lines of organisms show similarities in origin, food and water circulation, while at the same time showing differences in disease prevention and environmental dependency.
Genetic mapping has confirmed the origin of plants to be from an ancestral alga. Modern phylogenetics categorizes green algae and higher order plants into a new kingdom called Viridiplantae. As Viridiplantae organisms evolved, they eventually sprawled from freshwater and came to evade land. Horizontal gene transfer (HGT) and selective pressures caused a large diversification and thus gave rise to three types of land plants (Figure 1): bryophytes, tracheophytes, and seed plants (*Puigbò et al., 2009; Raven et al., 2008). Bryophytes, which include liverworts, hornworts, and mosses arose 450 MYA, and thus began the terrestrial colonization of plants. Tracheophytes first appeared about 420 MYA are plants specialized in vascularization—they were among the first plants to tissue that allowed for the distribution of material throughout their bo...
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...Life’ in the thicket of the phylogenetic forest. BMC Journal of Biology 8:59.
Raven, PH, Johnson, GB, Losos, JB, Mason, KA, Singer, SR (2008) Biology. Singapore: McGraw-Hill International.
*Stiller, V (2009) Soil salinity and drought alter wood density and vulnerability to xylem cavitation of baldcypress (Taxodium distichum) seedlings. Environmental and Experimental Botany 67: 164-171.
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Figures1-3 are courtesy of the McGraw-Hill Companies (Raven, 2008)
Figure 4 is courtesy of Journal of Obesity (Iacobellis, 2006)
Cain, M. L., Urry, L. A., & Reece, J. B. (2010). Campbell Biology. Benjamin Cummings.
2)Campbell, Neil A., and Jane B. Reece. Biology. San Francisco, CA: Benjamin Cummings, 2008. Print.
Miller, K. R., & Levine, J. S. (2010). Miller & Levine biology. Boston, Mass.: Pearson.
There are two basic theories on the evolution of epiphytes. The first theory indicates that epiphytes may have been shade adapted plants, struggling for light that moved into the canopy. The second theory suggests that plants preadapted to high sun exposure moved from dry savannahs and steppes into the canopy (Luttge 1989).
5 Jones, M. , Fosbery, R. , Taylor, Dennis. , (2007), Biology 1, Cambridge University Press, Cambridge
As a result of these factors, the flora has adapted to these conditions in a variety of ways including their shape, leaf type, root system, and color. One of the most prominent adapt...
Schulman, Joshua M., and David E. Fisher. "Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, 28 Aug. 0005. Web. 24 Apr. 2014.
The communities of various native plants have been significantly minimized as a result of ...
Jackson, R.D. 1986, Remote sensing of biotic and abiotic plant stress. Annual Review Phytopathology, 24, pp. 265-287.
Miller, K. R., & Levine, J. S. (2010). Miller & Levine biology. Boston, Mass: Pearson
3 Leicht B. G., McAllister B.F. 2014. Foundations of Biology 1411, 2nd edition. Southlake, TX: Fountainhead Press. Pp 137, 163-168, 177-180,
Wen, Chuck K., Pamela L. Hudak, and Stephen W. Hwang. "Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, 06 Apr. 2007. Web. 13 Apr. 2014.
Plant defences are those mechanisms employed by plants in response to herbivory and parasitism. According to Hanley et al. (2007), “the tissues of virtually all terrestrial, freshwater, and marine plants have qualities that to some degree reduce herbivory, including low nitrogen concentration, low moisture content, toxins or digestibility-reducing compounds”. The type of chemical defence may be species specific (Scott 2008). The defences that plants possess may be in the form of chemical production or in the form of physical defences such as thorns or spikes and even through reinforced, rigid leaves. “The compounds that are produced in response to herbivory can either have a direct effect on the attacker itself (e.g. toxins or digestibility reducers), or serve as indirect defenses by attracting the natural enemies of the herbivores” (Bezemer & van Dam 2005). This essay will focus on chemical plant defences and in particular the effects of terpenes, phenolics, nitrogen-based defences as well as allelopathy in plants.
How do plants resist being uprooted during typhoons? How do they absorb water? The answer lies on a particular plant structure, which is called the root. Basically, a monocot and a dicot root differ but also have common parts like the xylem and the phloem. Through examining the roots using the light microscope, the students would hopefully be able to understand how the root is designed to perform its vital functions. A root tip basically has 4 main regions, the root cap, the meristematic region, the region of cell elongation, and the region of cell differentiation. These parts are all essential for a root to function properly, thus further stressing its importance in t...
Campbell, N. A. & J. B. Reece, 8th eds. (2008). Biology. San Francisco: Pearson Benjamin Cummings.