All animals have the ability to regenerate tissue and repair their body after it has been damaged or a part of the body has been lost—to varying degrees. Higher vertebrates, including mammals, are able to regenerate only very small parts of their bodies, such as portions of skin or muscle, while lower animals can regenerate entire body parts. Dugesia tigrina, or brown planaria, can regenerate a whole body from a piece one-eighth the size of its original body.
Regeneration consists of three basic processes, that sometimes occur simultaneously and at other times sequentially at the site of the injury:
- Loss of differentiation in tissues near the injury and migration of new cells to the injury, resulting in a mass of undifferentiated tissue at the site.
- Redifferentiation of cells into various tissues.
- Reorganization of tissue into the original form by differential growth (the growth of newly generated tissues at different rates than the rest of the body’s tissues.)
Continue reading ‘Introduction to Planaria Regeneration’
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Barn Owls (Tyto alba) are found throughout the temperate regions of the world. This worldwide range categorizes the Barn Owl as a cosmopolitan species. The Barn Owl traditionally lived and hunted in open grasslands and nested in large, hollow trees or caves. This still holds true today, but as man cleared land for agricultural use the Barn Owl has been able to adapt and expand its territory, taking advantage of the millions of acres now used for raising crops and grazing cattle. Even the man-made structures in these areas are often exploited by Barn Owls as nesting sites. These include lofted barns, silos, grain bins, fire towers, duct work in abandoned gins and factories, culverts, and occasionally even wells.
As with most other raptors (a collective term for all hawks, falcons, eagles, and owls), the Barn Owl feeds primarily on mammals and other birds. The types of mammals and birds that Barn Owls choose make their pellets ideal for classroom study. Favored among Barn Owl prey are the insectivores (shrews and moles), small rodents (mice, voles, and rats), and small birds (sparrows, blackbirds, and starlings). These prey animals all commonly thrive in the areas where Barn Owls live. This is because insectivores, small rodents, and many birds feed on the naturally occurring vegetation, as well as agricultural crops and insects that feed on these crops. Continue reading ‘Introduction to Owl Pellets’
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Anthropogenic (human generated) waste materials are a source of great concern. The amount of space on the planet is finite, and as the human population expands, available space decreases. There are few truly wild regions left in the world due to the growth of the human race. With this growth comes serious problems. Where do we live? Where can we grow food? What about the by-products of human existence? The latter represents perhaps the greatest dilemma. Everyday human life produces a staggering amount of waste material. Much of this waste is carted off to landfills, where it can be left to decompose over a period of years.
Certain human waste products, such as plastics and metals, do not decompose readily, and must be left in the landfill for hundreds or thousands of years. Others decompose rapidly, breaking down in just a few weeks. Most often, these short-lived wastes are organic in nature, mostly leftovers from your dinner and grass clippings, weeds and sticks from your yard. That’s right, food and grass. Continue reading ‘Composting’
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The way animals perform and evolve over time can be attributed to their surrounding environments. The responses to such environments in some species can be modified through experience, whether it occurs internally or externally. An animal will use its nervous system to detect and process information from its surrounding environment. The nervous system, along with the endocrine system, helps contribute to an animal’s behavior. When this occurs, genes influence the coordinated responses to stimuli. This is known as animal behavior.
Animal behavior can be broken down into different categories: taxis, reflex, cyclic behavior, territorial behavior, migration, communication, learning, and social behavior. Everything that an animal does on any given day, whether it is simple or complex, can be considered animal behavior. These behaviors include any activity that occurs in response to stimuli. Continue reading ‘Animal Behavior’
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Sexual reproduction provides a mechanism to produce genetic variation, as the genes of two different individuals are arranged in various ways. This requires a reduction in the chromosome number of the parent cell, normally diploid, to half that, or haploid, in somatic cells. The type of cell division resulting in half the chromosome number of the parent cell is called meiosis.
In meiosis, a germ cell divides into four haploid gametes. When two gametes, typically an egg and sperm for most animals, combine during fertilization to form a zygote, the diploid chromosome number is restored. Meiosis consists of one DNA replication and two nuclear divisions, meiosis I and II. This results in the formation of four daughter cells, each with only half the number of chromosomes of the
parent. Continue reading ‘Sordaria Genetics Background’
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Photosynthesis, essential for life on Earth, is the biological process whereby green plants, algae, and certain protists and bacteria convert light energy into chemical energy. Green pigments, called chlorophylls, absorb the light energy, which is incorporated into the molecular structure of simple sugars. This process produces a wide range of organic compounds, mostly simple sugars, known as monosaccharides,
such as glucose. The simple sugars provide the basic materials for the synthesis of more complex carbohydrates, fats, and amino acids. Amino acids can, in turn, be synthesized into proteins. Continue reading ‘Photosynthesis and Cell Respiration’
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For many centuries, people believed that the increase in the size of a plant was caused by the intake of material from the soil. It was not until a Belgian physician, Jan Baptista van Helmont (circa 1577-1644), performed an experiment that demonstrated conclusively what we accept today: the increase in the size of a plant is not due simply to the plant obtaining a mystery substance from the soil; plants gain what they require through the process of photosynthesis.
Photosynthesis uses energy from light captured by photosynthetic pigments, and splits water molecules in the process. The plants fix carbon from carbon dioxide into glucose and fructose chains and oxygen is released as a byproduct. In many plants the sugars then combine to form long chains known as starches. Many plants store their photosynthetic products this way. Continue reading ‘Chromatography of Spinach’
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