Part I: Mendel and His Discoveries Answer each of the following questions and include at least one website for each question that pertains to the question. 1. Stands of aspen trees often are a series of genetically identical individuals, with each succeeding tree growing from the wavered shoot of another tree. Using what you’ve learned of genetics I this chapter, would you expect one aspen tree in a stand to differ greatly from another in its phenotype? Would you expect each to look exactly like the next in terms of phenotype?
Why or why not? http://treephys. oxfordjournals. rg/content/31/1/68. full http://forestry. about. com/od/hardwoods/ss/aspen_4. htm When discussing phenotypes, we are looking at the physical characteristics of the trees. Several variables could have an effect on the development of each aspen tree stand, causing them to have different characteristics. Because aspens thrive in sunny areas, those that grow in a brighter area could likely be taller and have healthier foliage than stands growing in shady areas. The overall appearance can also be affected by the quality and nutrition of the soil in which they are planted.
Aspen stands in California often thrive in areas that have been ravaged by forest fires that leave behind enriched soil and clear away any obstruction to sunlight. Aspen trees have the ability grow and proliferate from the root systems of other aspens, causing them to be a series of genetically identical individuals. Stands with extremely mature root systems and taller trees tend to have difficulty in water distribution, which has an adverse effect on the thickness of their leaves. Comparison between trees in younger stands would not be the same as in older stands.
We must also consider the health of the seed in which the stand was started from. If the initial aspen seed of a stand were somehow damaged, we would not expect its yield to be as phenotypical as the yield from a healthy seedling planted in the same area. Aspen seeds transplanted by a home owner for landscaping would likely vary in characteristics from aspens that have been growing wild from ancient root systems in West Virginia. In general, a person could look at any aspen tree and identify it’s phenotype by recognizing its’ bark, stems, and leaves.
However, if a closer look was taken, we would find that aspens of different sets would at least have minor differences caused by environmental and age factors. 2. If ,as the text states, the effects of genes can be expected to vary in accordance with the environment in which these genes work, would you expect this phenomenon to be applicable to human genes, such as those that help produce such traits as height, weight, or introversion and extroversion? Why or why not? http://www. answers. com/topic/gene-and-environment http://www. scientificamerican. com/article. cfm? id=how-much-of-human-height http://en. ikipedia. org/wiki/Extraversion_and_introversion#Eysenck. 27s_theory There are many environmental factors that can determine whether or not an unfavorable gene will express itself in a human. For example, a person’s height and weight could be affected by problems with their pituitary gland caused by elements of their environment. If the person were exposed to radiation or outside chemicals, it could lead to a tumor on their pituitary gland; in turn altering the function of the gland. The gland may begin to release irregular amounts of human growth hormone, causing greater or less height/weight than is typical.
Height and weight abnormalities could also be linked to lifestyle, cultural differences, and nutrition. Introversion and extroversion are greatly impacted by environment, but not entirely. Twin studies have found that there is a genetic component to personality and behavior related to introversion and extroversion. The studies have also shown that the way a human is nurtured and the culture in which they live can account for much of a person’s behavior. We could find examples of this in comparing twins who were reared in different settings that have similar traits to twins reared together who have remarkably different traits.