Radioactivity is the emission of tiny, invisible radio signa…
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Rаdiоаctivity is the emissiоn оf tiny, invisible rаdio signals by the nuclei of certain atoms.
Pаrt IV: Underline the subject(s), highlight the mаin verb(s), аnd add a cоmma if necessary. NOTE: Cоpy the entire sentence. Use Ctrl and C tо copy; use Ctrl V to paste.People do not know how to pay the late fees so the instructions are on the website.
DIRECTIONS: Reаd the pаssаge and answer the questiоns. The War оn Allergies A Suppоse that 54.3 percent of your country’s population had cancer. That figure might set off a nationwide panic—a search for something wrong with people’s diet, the environment, activity levels. In fact, that’s the percentage of Americans who show a positive skin response to one or more allergens. B The manifestations of allergy—sneezing, itching, rashes—are signs of an immune system running amok, attacking foreign invaders—allergens— that mean no harm. Allergens include pollen, dust mites, mold, food, drugs, stinging insects, or any other substance to which the body can choose to react, or overreact. Allergies rarely kill. They just make the sufferer miserable—sometimes for brief periods, and sometimes for life. C Allergies are essentially an epidemic of modernity. As countries become more industrialized, the percentage of population affected by them tends to grow higher. There are remote areas of South America and Africa where allergies are virtually nonexistent. D In contrast, six percent of young children in the U.S. today have food allergies. Federal legislation requires manufacturers to clearly label whether major allergens—peanuts, soy, shellfish, eggs, wheat, milk, fish, and tree nuts—are ingredients in any product. Children who cannot tolerate these foods sit at special tables at lunchtime; there are websites and support groups for parents who homeschool their severely allergic children. E Here’s how an allergy develops: One day, a body is exposed to a protein in something that seems perfectly harmless—the wheat flour, say, in a home-baked muffin. But for some unclear reason, the body looks at the protein and sees trouble. There will be no symptoms at first, but the body is remembering—and planning. F That first exposure causes the immune system to produce an antibody called IgE (immunoglobulin E). Then IgE antibodies attach to certain cells, called mast cells, in tissue throughout the body. There they stay like wary soldiers waiting for war. With a second exposure, even months later, some of the allergen binds with the IgE on the mast cell. This time, the mast cell releases a flood of irritating chemicals, which cause inflammation and itching. G A minor or isolated reaction can become more serious with repeated exposure to an allergen, or when other cells involved in the immune system, the T cells, come into play. Certain T cells remember the “insult” of the allergen and ensure that some part of the body keeps becoming inflamed. Often the allergen and the immune system become increasingly antagonistic, and the reaction worsens. H There is, unquestionably, a hereditary component to allergies. In some cases, people with allergies show signs of asthma. A child with one asthmatic parent has a good chance of developing the condition. If both parents have asthma, the chance of occurrence increases. I Still, the rise in allergies is too rapid to be explained solely by genetics. “The genetic pool can’t change that much in such a short time,” says Donald Leung, director of an allergy-immunology program in the U.S. “There have to be environmental and behavioral factors as well.” Dozens of theories have blamed everyone from urban landscapers for favoring male plants (the ones that produce pollen), to women who don’t breastfeed. Breastfeeding, the theory goes, confers greater protection against allergies. J Another probable factor: diet. “Reduced fresh fruit and vegetable intake, more processed food, fewer antioxidants, and low intake of some minerals—these are all shown to be a risk,” says professor of medicine Harold Nelson, considered one of the foremost experts on allergies in the U.S. K The use of antibiotics may also be an underlying cause of rising allergy rates. Certain bacteria in the intestine are associated with greater or lesser chances of having allergies. Researchers believe, as Donald Leung says, “Overuse of antibiotics may be disrupting certain gut flora that suppress allergy.” L Another prime culprit: environmental pollutants. Exactly what pollutants and in what quantities are a source of heated debate. One of dozens of examples: Children who are raised near major highways and are exposed to diesel fumes from trucks register an increased sensitivity to allergens they already react to. M Ironically, it’s not just the pollutants that are affecting us. It may be too much cleanliness. A prevalent theory among allergists is known as the hygiene hypothesis. While it’s true that industrialization brings with it better health care and fewer serious childhood infections, it also brings an obsession with cleanliness. We are not exposed to dirt at a young enough age to give our immune systems a good workout. Also, because of the high cost of energy, more homes are built with better insulation—insulation that seals in mold and dust. N “The hygiene hypothesis has been on the scene since people first started looking at allergies,” says associate professor Andrew Liu. “John Bostock, the guy who first identified hay fever in 1819, noted that it was a condition of the educated. He couldn’t report any cases among poor people.” O But if dirt is a good thing, why are allergies and asthma so prevalent today in poor, inner-city neighborhoods? “It’s not just a question of exposure to dirt that reduces allergies—it has to be the right kind of dirt,” says Liu. “We’re talking about exposure to endotoxin and good microbes in soil and animal waste.” Research supports the hygiene hypothesis. “There was a famous study,” says Harold Nelson, “where one of the protective factors for asthma was having a pig in the house.” P Since most of us are unable to room with a pig, we have to come up with a plan. Can we avoid allergies altogether? Can we get rid of allergies we already have? Can we desensitize our immune systems? “We still don’t know exactly how to prevent allergies,” says Andrew Liu. “We know the immune response is supposed to be a helpful one, that it’s not supposed to be the cause of disease. We know that the immune system of someone with allergies needs to be reeducated. But how? It’s not always clear.” Leung agrees, adding, “If you are exposed to . . . microbial products early in life, it may prevent allergies. But later in life, the early exposure may actually make things worse.” Q There are those who argue that to prevent allergies, we should reduce exposure to harmful allergens early on. Others believe allergens should be administered in large quantities at a young age. Many believe it depends on the specific allergen. And food allergies may work on an altogether different principle. Confused? So are the allergists. R But there is hope that allergy sufferers may one day live in a world that’s far more comfortable. Suddenly there’s a booming market for products and services that were unimaginable 30 years ago. Hotels offer allergy sufferers rooms with special ventilation systems and linens washed with nontoxic products. Scientists are finding ways to get rid of the allergenic proteins in common offenders. Researchers at the University of Melbourne in Australia also claim to have developed the first hypoallergenic rye grass: It doesn’t cause hay fever. S But the questions remain: Are allergies truly preventable? How much genetic engineering is feasible? And even if we can eliminate the allergens we fight today, what will our immune systems decide are the enemies tomorrow? Choose the best answer.In Paragraph D, which of the following are major allergens?