Thursday, April 14, 2011

Blog #10 Why is dissection an important part of a biology curriculum? Which animals and/or plants should be included in biological studies?

Dissection is usually applied to the examination of plants and animals. The term is also used in relation to mechanisms, computer programs, written materials, etc., as a synonym for terms such as reverse engineering or literary deconstruction. Dissection is usually performed by students in courses of biology, botany and anatomy and in association with medical and arts studies. Vivisection refers to the dissection of a living animal, often for the purposes of physiological investigation and nowadays always under heavy sedation. However, the term is no longer widely used, in part because more sophisticated techniques have superseded it for many applications. The term is now almost entirely used in a pejorative sense by those who oppose animal testing of any sort. Dissection is often performed as a part of determining a cause of death in autopsy (on humans) and necropsy (on animals) and is an intrinsic part of forensic medicine, such as would be practiced by a coroner. Dissection is important because we learn the insides of animals and plants. I think the kind of animals and/or plants that should be included in biological studies is wild animals and plants. The kind of animals and plants that live in the wild and forests. Dissection teaches us about animals and plants by checking their insides.



Thursday, April 7, 2011

Blog 1 Why is evolution a theory and not a law?

The statement "evolution is both a theory and a fact" is often seen in biological literature. Evolution is a "theory" in the scientific sense of the term "theory"; it is an established scientific model of a portion of the universe that generates propositions with observational consequences. Such a model both helps generate new research and helps us understand observed phenomena. When scientists say "evolution is a fact", they are using one of two meanings of the word "fact". One meaning is empirical: evolution can be observed through changes in allele frequencies or traits of a population over successive generations. Another way "fact" is used is to refer to a certain kind of theory, one that has been so powerful and productive for such a long time that it is universally accepted by scientists. When scientists say evolution is a fact in this sense, they mean it is a fact that all living organisms have descended from a common ancestor (or ancestral gene pool) even though this cannot be directly observed. This implies more tangibly that it is a fact that humans share a common ancestor with all living organisms. Evolution is usually defined simply as changes in trait or gene frequency in a population of organisms from one generation to the next. However, "evolution" is often used to include the following additional claims:
  1. Differences in trait composition between isolated populations over many generations may result in the origin of new species.
  2. All living organisms alive today have descended from a common ancestor (or ancestral gene pool).
 

Blog # 9 Define the different forms of community interaction: competition, commensalism, mutualism, predation, parasitism Give an example and a picture for each

Competition is a contest between individuals, groups, animals, etc. for territory, a niche, or a location of resources. It arises whenever two or more parties strive for a goal which cannot be shared. Competition occurs naturally between living organisms which co-exist in the same environment. For example, animals compete over water supplies, food, and mates, etc. Humans compete for water, food, and mates, though when these needs are met deep rivalries often arise over the pursuit of wealth, prestige, and fame. Business is often associated with competition as most companies are in competition with at least one other firm over the same group of customers. Commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped. Mutualism is any relationship between individuals of different species where both individuals derive a benefit. An example of mutual symbiosis is the relationship between the ocellaris clownfish that dwell among the tentacles of Ritteri sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the clownfish from its predators. A special mucus on the clownfish protects it from the stinging tentacles. Predation describes a biological interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked). Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption. A parasitic relationship is one in which one member of the association benefits while the other is harmed. Parasitic symbioses take many forms, from endoparasites that live within the host's body to ectoparasites that live on its surface. In addition, parasites may be necrotrophic, which is to say they kill their host, or biotrophic, meaning they rely on their host's surviving. Biotrophic parasitism is an extremely successful mode of life. Depending on the definition used, as many as half of all animals have at least one parasitic phase in their life cycles, and it is also frequent in plants and fungi. Moreover, almost all free-living animals are host to one or more parasite taxa. An example of a biotrophic relationship would be a tick feeding on the blood of its host.