PROSE FICTION: This passage is adapted from the novel Tropic of Orange: A Novel by Karen Tei Yamashita (©1997 by Karen Tei Yamashita).

This passage uses elements of a literary genre called magic realism to describe a mysterious thin line that is simultaneously real and imaginary.

The tree was a sorry one, and so was the orange. Rafaela knew it was an orange that should not have been. It was much too early. Everyone said the weather was changing. The rains came sooner this year. The tree had been fooled, and little pimples of budding flowers began to burst through its branches. And then came a sudden period of dry weather; the flowers withered away, except for this one. Perhaps it had been the industrious es of the African bees, their furry feet dusted heavily with yellow pollen, that had quickly mated the flower to its future, producing this aberrant orange-not to be picked, not expected and probably not very sweet.

But from the very beginning, Rafaela somehow felt this particular orange was special. Perhaps it was her desire to see a thing out of season struggle despite everything and become whole. As time went on, she found herself watching the orange, wandering out to the tree every day even in the rain, feeling great contentment in the transition of its small growing globe, first from green and then to its slow golden burnish.

But there was something else. Just where its tiny bud had broken through the tree's branch, Rafaela noticed a line-finer than the thread of a spiderweb- pulled with delicate tautness. It was most visible in the dewy mornings as the sun rose from the east; at other times, it was barely visible. But she had always sensed its presence. If she could not reach out and touch it she sensed its peculiar, very supple strength. Rafaela knew that it ran across the property. In fact, she sensed that it continued farther in both directions, east and west, east across the highway and west toward the ocean and beyond.

In the days when the orange was a blossom of soft petals, its fragrance surprised her. She had passed beneath the orange several times, drawn to its sweet scent before she had discovered it. The perfume could only be emanating from that curious flower. She came often then to secure the whiff that tingled her deep memory. It was then that she noticed the line. And when the baby orange appeared, it seemed to grasp that line as its parent, if a line could be a parent.  As expected, the orange did not grow to be very big or seem very succulent but it did begin to hang rather heavily. And when the salty wind blew west from the sea rocking it back and forth like a small cradle the curious line-now running through the growing orange- rocked back and forth with it like a lullaby.

Rafaela and her son Sol walked hand in hand past the orange tree, careful not to disturb the lizards and beetles waiting breathlessly beneath scattered leaves and brush. For three days now, it had not rained. And yet any cool surface bled the air's moisture. Rafaela felt this wetness; it gathered in tiny molecules over her skin. It was a little before noon, and the sun was particularly bright and oppressive that day. If Rafaela had bothered to look at the calendar, she would have noticed that it was Monday, June 22. She might have also noticed the lunar signs in the corner of the calendar and the small print that said summer solstice.

She glanced briefly at the orange with some satisfaction and hurried toward the house. "Come on Sol. It's much too hot out here today." His little quick steps patterned behind, dancing around the young trees, and then ran forward. She followed Sol who seemed to be following a path of his own, but upon closer inspection, he was tracing the path of a very thin but distinct shadow stretched in a perfectly straight line along the dirt and sand. There were no telephone cables or electric lines above, nothing to cast such a shadow and yet it was clearly there Rafaela glanced back toward the orange tree and the single orange, suddenly aware of the only possible and yet entirely impossible thing that could obstruct the intensity of the sun's light at this hour, slicing the heavy atmosphere with cruel precision. Indeed the sun was a great ball of fire directly above the orange tree. It seemed even to point at the tree, at the strange line, at the orange itself.

Rafaela ran after Sol into the cool shadows of the house. There was a sudden gust of tepid wind, and from the corner of her eye, she thought she saw the line's razor shadow dip away, south. Rafaela felt dizzy nausea. She did not realize that the orange had fallen irresistibly from a height of two meters, rolling in dusty turbulence down a small slope, under the barbed-wire fence, and just beyond the frontiers of the property to a neutral place between ownership and the highway.

SOCIAL SCIENCE: This passage is adapted from the article "The Green Monster" by James E. McWilliams (©2009 by Washington Post Newsweek Interactive Co. LLC).

GMO refers to "genetically modified organisms." A genetically modified crop results from the laboratory insertion of a gene from one organism into the DNA sequence of another in order to confer advantageous traits such as insect resistance, drought tolerance, or herbicide resistance. Today almost 90 percent of soy crops and 80 percent of corn crops in the United States sprout from genetically engineered seeds. Forty-five million acres of land worldwide contain genetically engineered crops. From the perspective of commercial agriculture, the technology has been seamlessly assimilated into traditional farming routines.

Not all consumers share the enthusiasm. It's as likely as not that you know GMOs by their stock term of derision: Frankenfoods. The moniker reflects a broad spectrum of concerns: Some anti-biotech activists argue that these organisms will contaminate their wild cousins with GM pollen and drive native plants extinct. Others suggest that they will foster the growth of "superweeds"-plants that develop a resistance to the herbicides many GMOs are engineered to tolerate. And yet others fear that genetic alterations will trigger allergic reactions in unsuspecting consumers. Whether or not these concerns collectively warrant a ban on GMOs-as many environmentalists would like to see is a hotly debated topic. The upshot to these potential pitfalls, however, is beyond dispute: A lot of people find this technology to be creepy.

Whatever the specific cause of discontent over GM crops, popular resistance came to a head in 2000, when the National Organic Program solicited public input on the issue of whether GM crops should be included in an organic food program. In response, sustainable-food activists deluged officials with a rain- forest's worth of letters-275,000, to be exact-beating the measure into oblivion. Today, in the same spirit, environmentalists instinctively deem GMOs the antithesis of environmental responsibility.

Many scientists, and even a few organic farmers, now believe the 2000 rejection was a fatal rush to judgment. Most recently, Pamela Ronald, a plant pathologist and chair of the Plant Genomics Program at the University of California-Davis, has declared herself one such critic. She argues that we should, in fact, be actively merging genetic engineering and organic farming to achieve a sustainable future for food production. Her research-which she conducts alongside her husband, an organic farmer-explores genetically engineered crops that, instead of serving the rapacity of agribusiness, foster the fundamentals of sustainability. Their endeavor, counterintuitive as it seems, points to an emerging green biotech frontier-a hidden realm of opportunity to feed the world's impending 9 billion a diet produced in an environmentally responsible way.

To appreciate how "responsible genetic modification" isn't an oxymoron, consider grass-fed beef. Cows that eat grass are commonly touted as the sustainable alternative to feedlot beef, a resource-intensive form of production that stuffs cows with a steady diet of grain fortified with antibiotics, growth hormones, steroids, and appetite enhancers that eventually pass through the animals into the soil and water. One overlooked drawback to grass-fed beef, however, is the fact that grass-fed cows emit four times more methane-a greenhouse gas that's more than 20 times as powerful as carbon dioxide-as regular, feedlot cows. That's because grass contains lignin, a substance that triggers a cow's digestive system to secrete a methane-producing enzyme. An Australian biotech company has recently produced genetically modified grass with lower amounts of lignin. Lower amounts of lignin mean less methane, less methane means curbed global warming emissions, and curbed emissions mean environmentalists can eat their beef without hanging up their green stripes.

When commercial farmers hear about GM grass, they're excited. And when they hear about other products in the works, they're also excited. And they're excited not only because these products have the potential to streamline production but also because GM technology allows them to play a meaningful role in reducing their carbon footprint.

Given the potential of these products to reduce the environmental impact of farming, it's ironic that traditional advocates for sustainable agriculture have led a successful campaign to blacklist GMOs irrespective of their applications. At the very least, they might treat them as legitimate ethical and scientific matters deserving of a fair public hearing.

HUMANITIES: This passage is adapted from the article "British Modernism's Many Manners ... and Its American Admirers" by Steve Moyer, which appeared in 2009 in Humanities: The Magazine of the National Endowment for the Humanities

Bloomsbury, the group of innovative writers and artists, came out of its embryonic phase around 1910 as the Victorian era finally expired with the funeral of Edward VII. Its young mix of writers, thinkers, and artists stood at the vanguard of a shift in manners away from nineteenth-century formality and reticence and toward twentieth-century candor and playfulness. Male and female, mostly in their twenties, the Bloomsbury lot addressed each other by their first names, and, till the wee hours of the morning, reflected on how to spend their lives.

Fascinated by the difference between the world of appearances and the world of reality, in the visual and literary arts, the Bloomsberries (as they were sometimes called) experimented with brush and pen to express above all the subjective qualities of their work. For the painters, who opened themselves up to the currents swirling around on the [European] Continent since the final days of Impressionism, this translated into an emphasis online, mass, contour, and the rhythms they create.

If anyone's work by the Bloomsbury painters sums up adequately the era's avant-garde break with London's Victorian taste in art, and the influence of the French Post-Impressionists on British artists, it would be Vanessa Bell's 1915 oil on canvas of Mary St. John Hutchinson. With arched eyebrows, lips slightly pursed, and cool self-assurance, Mrs. Hutchinson sits noticing something to her left, and the viewer, disarmed at first perhaps by the flatness of the composition and the coarse brushwork, feels as much as sees the various tones of the few colors in the portrait-ochre, green, and pink, and, where the whites of the eyes should be, teal. The work broke all the reigning conventions in British painting. Treatment of subject, use of line and color, lack of shadowing, and the solidness of the background in relation to the figure are all in sync with the modernist modes that had been in style on the Continent, most notably in France.

If Bloomsbury had been an art department, Roger Fry would have been faculty chairman. Painter, curator, and instigator, Fry studied the sciences at Cambridge University in the 1880s, developing a habit of skepticism that would serve him well as he guided painters Vanessa Bell and Duncan Grant toward modernism in the years leading up to World War I.

Influenced by paintings they had seen in France, Fry, Grant, and Bell experimented early on with cubism and abstraction, which helped the latter two immensely 50 in their designing and painting of objects. Fry had also convinced the traditionally trained Grant to lighten the colors of his palette and Bell to express her feelings more completely. The result was an outpouring of their creative energy. Bell wrote, "That autumn of 1910 is to me a time when everything seemed springing to new life- a time when all was a sizzle of excitement, new relationships, new ideas, different and intense emotions seemed to be crowding into one's life."

Bloomsbury's anti-Victorian revolt had, in fact, as much to do with getting back to Fry's perceptions of the great traditions in art as it did with youthful rebellion. In France, the painter Simon Bussy acted as cicerone for the group, introducing them to French artists and reaffirming the necessity to study the old masters.

A Victorian ideal the group chose to keep was the veneration of comfortable home life but with the subsequent Bloomsbury love of color, brightening what they saw as stuffy and stodgy in the homes of their youth. Fry felt, moreover, that nineteenth-century British artists in general, and Victorian painters in particular, had lost their way by becoming preoccupied with attempts at highly detailed and, in some cases, photo graphically accurate representations of reality.

The French painters Fry admired had been trending toward a new aesthetic for over two decades. But these artists, unlike the Impressionists, had little in common as a group except for the fact that they were all influenced in some way by Impressionism's ideals; they passed through the era, learning from it and reacting to it while continuing to develop their own visions. Gauguin had been vibrantly imbuing his work with desire and emotion; Matisse pared his down to a harmonious interplay of line and rhythm, and Cezanne had been looking back to the masterpieces of primitive and epic works in order to bring about a monumental effect. Fry's study of their painting taught him a new language of design, which he wanted to try out himself and convince other British painters to take up.

NATURAL SCIENCE: This passage is adapted from the article "What Causes Ice Ages?" by Traci Watson (©2002 by U.S. News & World Report).

The Cenozoic era, the most recent of the four major subdivisions of geologic history, began about sixty-five million years ago and continues to the present.

 Scientists have long known about the giant ice sheets that the Cenozoic Ice Age ushered in. Even in the mid-19th century, they knew that glaciers had repeatedly raked swaths of Europe and North America in the not-so-distant past. Yet despite the efforts of marine geologists, atmospheric chemists, oceanographers, and more, no one knows what caused the ice ages.

If they tried, scientists could hardly invent a more difficult mystery to crack. Most of the events in question took place tens or hundreds of millions of years ago. The shift in the Earth's climate was subtle: The planet is only 10 degrees cooler today than it was in the tropical period just before the Cenozoic.

Sixty million years ago, the planet started to cool in earnest. Twenty-five million years later, Antarctica was buried under a thick sheet of ice; 18 million years after that, glaciers overran Greenland. Last of all ice sheets invaded North America and Europe, retreated, advanced, retreated, and so on. Today, the planet is enjoying an "interglacial," one of the slightly warmer periods when the glaciers slink back to the poles.

The cause of the ice ages is a remarkably consensus-free scientific topic, but on one point most researchers agree: The cooling that started 60 million years ago was caused by a drop in carbon dioxide in the atmosphere. Carbon dioxide is a so-called greenhouse gas. It traps sunlight close to the Earth, raising the planet's temperature. Less carbon dioxide in the atmosphere means colder weather.

But why did carbon dioxide levels fall? The leading theory is that two of the Earth's tectonic plates collided, forming the Himalayas.

Marine geologist Maureen Raymo, now at the Massachusetts Institute of Technology, worked out a scenario that is widely cited in the scientific literature-both favorably and not. Raymo noted that the Himalayas are taller than any other mountain range on Earth and that they formed at nearly the same time as the start of the ice ages. Scientists realize that carbon dioxide from the atmosphere combines with rain to make an acid that erodes rock; in the process, minerals such as calcium silicate in the rocks react with carbon dioxide moving the gas from the atmosphere. Therefore, eros10n on slopes as vast as the Himalayas', says Raymo, could reduce carbon dioxide levels enough to give the ice ages a push.

Raymo acknowledges that her idea has holes. Weathering on the scale she theorizes would devour so much carbon dioxide that soon there wouldn't be any left at all. Other scientists point to an opposite problem: The kind of minerals in the Himalayan rocks rarely consume carbon dioxide when they erode. The mystery of Cenozoic cooling has encouraged researchers to propose many other candidate culprits. One recent scientific paper theorizes that the key factor is the tons of sediment shed by the mountains every year. The sediment runs into the Indian Ocean and buries large amounts of marine plankton and other plants. Entombed along with the plants is their carbon dioxide, meaning less carbon dioxide in the atmosphere and therefore less warming. Solutions championed by other scientists include the evolution of grasses, which happened at roughly the right time and would have stored large amounts of carbon dioxide in the soil; and weathering of the mountains in either New Guinea or Siberia.

There is equally great bafflement over the much more recent Northern Hemisphere glaciations. For most of the Cenozoic Ice Age, the polar regions were the only place to suffer heavy invasions of ice. But 2.5 million years ago, glaciers moved into Europe and North America and have paid regular visits since. Scientists can explain the timing of these local ice ages. As the Earth's orbit slowly changes, so does the pattern of the sunlight falling on a given spot on the globe, triggering the glaciers' advance and retreat. The problem is that the orbital changes are not big enough to make or melt ice sheets.

What ice age scholars need are cold, hard data. For example, there are no direct measurements of atmospheric carbon dioxide beyond 200,000 years ago. Carbon dioxide levels are revealed by long cylinders of ice extracted from Antarctica. But there is no ice old enough to reveal the composition of the atmosphere millions of years ago.

"Information is pouring in now, and it is not con verging on a simple explanation," says Isaac Winograd, a hydrologist at the U.S. Geological Survey.

Until scientists can explain changes in Earth's climate past, they cannot be sure they aren't overlooking factors that could either counteract human-made warming or amplify it.