Answer to Question 1
The Toxic Substances Control Act (TSCA) . . . requires that, before manufacturing a new chemical in bulk, manufacturers must submit a pre-manufacturing report' to the EPA in which the environmental and human health impacts of the substance are assessed (including those that may derive from the ultimate disposal of the chemical). Depending on the results of the assessment, the manufacturer may be required to test the effects of the product on living things. Following the results of the testing, a product's uses may be restricted or a product may be kept off the market altogether.
Answer to Question 2
The promise of genetically modified crops has beenlike the Green Revolutionto increase food production. Among other aims, the objectives of genomics (genetically modified food) are (1) to incorporate resistance to diseases and pests that attack important tropical plants, (2) to increase tolerance to environmental conditions, such as drought and high salt levels, which stress most plants, (3) to improve the nutritional value of commonly eaten crops (like the work with golden rice), and (4) to produce pharmaceutical products in ordinary plants (pharma' crops'). . . . Among the important environmental benefits of bioengineered crops are reductions in the use of pesticides, because the crops are already resistant to pests; less erosion, because no till cropping is facilitated by the use of herbicide-resistant crops; and less environmental damage associated with bringing more land into production, because the existing agricultural lands will produce more food.
Concerns about genetic engineering technology involve three considerations: environmental problems, food safety, and access to the new techniques. A major environmental concern focuses on the pest-resistant properties of the transgenic crops. With such broad exposure to the toxin or some other resistance incorporated into the plant, it is possible that the pest will develop its own resistance to the toxin more rapidly and thus render it ineffective as an independent pesticide. Another concern is the ecological impact of the crops. For example, pollen from Bt corn (resistant to the corn borer) disperses in the wind and can spread to adjacent natural areas where beneficial insects may pick it up and be killed by the toxin. A third environmental concern arises because genes for herbicide resistance or for tolerance to drought and other environmental conditions can also spread by pollen to wild relatives of crop plants, possibly creating new or super' weeds. Food safety issues arise because transgenic crops contain proteins from different organisms and might trigger an unexpected allergic response in people who consume the food. The problems concerning access to the new technologies relate to the developing world. For the first few years, almost all genetically modified organisms were developed by large agricultural-industrial firms, with profit as the primary motive. Accordingly, farmers have been forbidden by contract from simply propagating the seeds themselves and must purchase seeds annually. Farmers in the developing countries are far less able to afford the higher costs of the new seeds, which must be paid up front each year.
The role of leptin in regulating appetite and metabolic rate.
Infection prevention and control
Examples of waste and hazard containers.
Hormonal control over male and female reproductive hormones.
Homeostasis and negative feedback as related to control of body temperature.
Gate control theory. A. open gate, B. closed gate