Carbon cycles through the ecosystem between the atmosphere, organisms (such as producers, herbivores, and carnivores) and decomposers. This natural cycle maintains a somewhat constant level of carbon in the atmosphere. The burning of fossil fuels releases carbon into the cycle that has been trapped inside the earth. How does this affect the cycle and what problems can this cause?
The two main processes of the carbon cycle are photosynthesis and metabolism. Plants and animals consume and express carbon dioxide in relatively equal measure. Human beings affect this fragile process by releasing fossil fuels into the atmosphere which produces surplus carbon. Those who support the concept of global warming argue that these surplus carbons, along with other greenhouse gases, are increasing the temperature of the planet (Kasting 1998).
Carbon naturally is in balance between released and stored materials. As carbon is released by the burning of fossil fuels, the locations for storage are being used up and thus higher percentages of carbon are being released into the atmosphere. Scientists argue that if fossil fuels are burned, the potentially consequences include tripling the current amounts of carbon dioxide in the atmosphere (Kasting 1998). This could potentially create an atmosphere which is no longer breathable by human beings and other mammals. Other potential consequences of the burning of fossil fuels could include the melting of glaciers and the elevation of sea level. This could lead directly to draughts which would then destroy crops and diminish food supplies.
2. Using Darwin's reasoning, explain how four species of lizards, all closely related, came to be separate species on a Caribbean island.
Darwin's theory was that mutation occurs every so often in a species. If this variation proves to be beneficial to the creature, then subsequent generations will be born with this adaptation. Subsequent generations will increase the strength of this differentiation, leading to a complete change in the species. Usually those with unsuccessful adaptations will not survive. Sometimes the adaptations lead to a division between two creatures. They will have slightly dissimilar mutations, both of which are successful. Their descendants will have more obvious versions of these adaptations until the two creatures, once a part of the same species have diverged and become completely different from their common ancestor.
The process of divergent adaptation, what is commonly called evolution, takes millions of years. Darwin believed that some species were closely related but still separate entities. The explanation for this could only be that they descended from a common ancestor (Postlethwait 2009). As the environment of a location changes, the creature must adapt or be unable to survive in the new climate. On one Caribbean island, several different species of lizards exist. This is explained by the unique adaptation which begins to separate similar creatures within the same generation. On the Galapagos Islands, Darwin discovered several variations of finches. Each different type had adaptation which better equipped them for certain tasks and determined how they fed and where they nested. All the birds, he determined, were descended from the same ancestral creature but became new types through millions of years of adaptation and change (Losos 2011).
3. During interphase the DNA is not visible through a microscope; it only becomes visible as chromosomes during mitosis. Why isn't the DNA visible during interphase and why would this be the case?
During interphase, the DNA is not visible because during this phase, the DNA is not condensed. DNA by itself is not visible, even with the use of a high-powered microscope. The only times that DNA can be seen are when the DNA is compacted and condensed (Herreid 2004). Scientists never see a single piece of DNA. Rather, they can see groupings of DNA when they are condensed.
It is during this phase that the DNA is being used in the process of protein synthesis by transcribing mRNA. This phase is important because the DNA is performing many processes which are necessary for the continuance of life (Herreid 2004). Since it is constantly in motion, the DNA is never still for a long enough period to condense and become visible.
4. How is it that, in meiosis, you can end up with four "daughter cells" that are all genetically different from one another?
During meiosis, there is a process called independent assortment. This means that at the end of meiosis, the cells produced can...
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