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define homeostasis and explain its significance

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Question:Explain "Standardized achievement tests" in terms of its significance in the context of psychological testing. 1k

Answers:Achievement tests very often have a psychological dimension or assess psychological parameters, such as sociability. In order for the results of an achievement test to be considered valid and useful, the test has to meet the requirements of the APA. These requirements are spelled out in - Standards for Educational and Psychological Testing, ADRA, APA, NCME Also see: A Handbook of Psychological Assessment in Business, Hansen and Conrad, eds. I hope this is helpful.

Question:Describe the concept of stoichiometric homeostasis. How does one test for its existence? Which types of organisms tend to exhibit stoichiometric homeostasis, and which do not. Finally, how the presence of lack of stoichiometric homeostasis in soil bacteria and plants affect the response of terrestrial nutrient cycles to additions of a limiting nutrient.

Answers:A dry topic. Not given to light replies - or in your case, any replies. So I'll tackle: Stoichiometric homeostasis: One of the most significant themes in ecology. This is the concept that compares the elemental makeup of the tissues in living organisms with their environment. Quoting biologist J. Persson at University of Oslo, and fellow scientists in their report, "To be or not to be what you eat: Regulation of stoichiometric homeostasis among autotrophs and heterotrophs": "Homeostasis is the resistance to change of consumer body composition in response to the chemical composition of consumer's food." Until recently, autotrophs were assumed to be flexible. In contrast, heterotrophs, which were "confined to a constant (strictly homeostatic) body composition," were not. Now there's evidence to challenge that. So these guys tested it. "We examined the degree to which autotrophs and heterotrophs regulate stoichiometric homeostasis (P:C, N:C, N:P, or % P and %N). ... There was a wide range of responses from strictly homeostatic to non-homeostatic. Even within heterotrophic organisms, varying levels of homeostasis were observed... [as well as] significant differences between groups. For example, aquatic macroinvertebrates were significantly more homeostatic in terms of P:C than terrestrial invertebrates." And "with regard to N:P, heterotrophs are significantly more homeostatic than autotrophs. ..." Studying stoichiometric homeostasis helps to clarify many soil food-web relationships, "commonly driven by elemental imbalances between consumers and their resources." In stoichiometrics, organisms become molecules and ecosystems are organisms. The link is referenced below. I highly recommend one of the greatest texts on this subject: "Ecological Stoichiometry: Biology of Elements from Molecules to the Biosphere" by Sterner and Elser. There is one chapter posted online, and some of it is worth posting here: "Redfield's congruence in nutrient ratios between plankton and their aquatic medium indicated a balanced flow of C, N, and P in and out of the biota. The 'Redfield ocean' is a biological circulatory system with constant C:N:P stoichiometry moving vast quantities of constant proportions of these three elements vertically over thousands of meters. A second congruence was that the line describing the N and P data had a zero intercept, indicating that these two elements would be depleted from ocean waters simultaneously. The same was not true for carbon: there was a surplus of carbonate when N and P were depleted." They continue: "Simultaneous depletion of N and P was surprising. There is no a priori reason to expect ocean water to contain N and P in proportions identical to biological demand. Why then should this measure of the chemistry of the ocean--such a vast proportion of the Earth's surface and subjected to major influences from geology, meteorology, and others--have an N:P ratio that matches biological demand? Redfield's (1958) answer was that the biota itself determined the relative concentrations of N and P in the deep sea. He suggested that it was P that ultimately determined the biological productivity of the world's oceans, and that biological feedbacks adjusted the level of N so that its availability matched the availability of P (Fal-kowski et al. 1998). Similar arguments were later applied to soils (Walker and Adams 1958, 1959). Redfield's findings were important in a very broad context: his work was instrumental in fostering a view that the ocean's biota has a major influence on the chemistry of even this vast volume of water. In their abstract, "Soil Nutrient Stoichiometry as Influenced by Fire Return Intervals in Ponderosa Pine Forests," researcher Joss Mckinnon and colleagues declared, "Nitrogen deficiency is the primary form of nutrient limitation experienced by vegitation in western Montana. However, an examination of the quantity of available N in soil will not provide a comprehensive view of nutrient limitation status due to the complex nutrient requirements of plant species. Rather an analysis of the ratio of plant available N to plant available phosphorus (P) provides a more precise characterization of the nutrient status of the soil. Limited research has examined the role of natural fire intervals on the stoichiometric relationship between these nutrients in this system. We identified seven clustered sites in wilderness areas that represent stands that have been exposed to fire 0, 1, 2, or 3 or more times in the last 120 years across three wilderness areas in the Inland Northwest. The sites with three or more fires represent a fire return interval similar to what is thought to be natural. Mineral soil samples were collected from each of the seven sites and analyzed for total C, N and P, potentially mineralizable N (PMN), NH4+, NO3- and PO43-. Forest litter and foliage samples were also collected and analyzed for total C, N and P. Discussion of the relati

Question:I have to take some summer notes for AP Chem this fall, and I have done some research own my own, but it is still really confusing. I need to be able to understand the following: 1. The rules for zeros (mainly when they count and a simple explanation of why) 2. Multiplying and Dividing 3. Addition and Subtraction 4. Exact numbers and when I should use them Please say it as simply as possible, because I have no experience with significant figures at all. Thank you so much!

Answers:1. Zeroes placed after the decimal point are significant figures. Hence, 3.00 has three significant figures. Zeroes before the decimal point are not significant figures. Hence, 300 has one significant figure. If a number ends in a decimal, then the units digit is significant. "300." has three significant figures. What if you want to show that 300 has two significant figures? The best way to do this is to write it in scientific notation: 3.0 10^2. This is applicable to all cases. 2. When you multiply or divide two inexact numbers, the number of significant figures is the smaller of the numbers of significant figures in the two operands. For example, multiplying a number with 5 significant figures by a number with 2 significant figures, gives a result with 2 significant figures. 3. When you add or subtract two inexact numbers, compare the least significant digits of the two numbers. The one with the greater place value determines the number of significant figures in the answer. For example, adding 123 to 0.45678 yields 123 as your answer. The first number has 3 in the units position; the second has 4 in the tenths position. The extra precision of 0.45678 is wasted. If we were adding 1234+0.56789, we would round 0.56789 up to 1 first, giving the answer 1235. 4. An exact number is one with an infinite number of significant figures. For example, in the equation d = 2r, the number "2" is exact. The diameter of any circle is _exactly_ two times the radius. The number 2 behaves as 2.00000000000000...... Generally, literal constants appearing in equations are exact numbers. Certain numbers have also become exact by definition; for example, c = 299792458 m/s _exactly_, because the meter was defined to make this true. IMPORTANT: Perform all calculations with as many significant figures as your calculator will allow, and only perform rounding off to the correct number of significant digits when you are _reporting_ the results. Why is this important? If you evaluate 1.0 + 0.2 + 0.2 + 0.2 + 0.2 + 0.2 + 0.2, and after adding each 0.2 you remove the tenths digit, your final answer will be 1.0. Instead what you should be doing is the calculation as precisely as possible to give 2.2, and round this down to 2.0 at the end.

Question:I am working on an experiment: How does temperature affect the haemoglobin level of brine shrimps? Since oxygen solubility is low in warm waters, we expect haemoglobin level to rise. I need to know the significance of this question. I was planning to link it to global warming, like how warm water affects marine life. But it is not a bad thing to have higher haemoglobin levels, so lthe link to global warming is rendered useless. Maybe I thought acclimatization could be an area of investigation. Increasing haemoglobin level is acclimatization which is also observed in humans at high altitude. So, is acclimatization a form of homeostasis? Is is also a result of evolution? Besides that, I can't think of any topic of significance to my experimental question. Please help, thanks.

Answers:I believe it is. Homeostasis is the central reason for many of our biological functions. However, is it a result of evolution.. to answer that one would have to believe in it, and I don't. This world required intelligent design my friend, just look at it.

From Youtube

Homeostasis :Betty is concerned about her husband, Bob, and his homeostasis. Bob does not like wearing a helmet while he rides his motorcycle. After warning Bob about one of the risks of disrupting homeostasis from a head-impact, she has a long discussion with her friend Meredith about homeostasis, she learns about Bob's accident. After the funeral, Betty has a chat with Natalie explaining what happened to Bob and how his homeostasis failed. Homeostasis is your body's physiological way of maintaining balance through its many complex systems. Extreme injurys such as head injuries can distrupt homeostasis.