LITERARY NARRATIVE: This passage is adapted from the article "Trading Stories" by Jhumpa Lahiri {©2011 by Conde Nast).

Books, and the stories they contained, were the only things 1 felt I was able to possess as a child. Even then, the possession was not literal; my father is a librarian, and perhaps because he believed in the collective's property, I had almost no books to call my own.

Our house was not devoid of things to read, but the offerings felt scant. There were books about China and Russia. My mother owned novels and short stories and stacks of a literary magazine called Desh, but they were in Bengali, I craved a house where books were a solid presence, piled on every surface and cheerfully lining the walls. 

What I really sought was a better-marked trail of my parents' intellectual lives: bound and printed evidence of what had inspired and shaped their minds. A connection, via books, between them and me. But my parents did not read me or tell me stories; my father did not read any fiction, and the stories my mother may have loved as a young girl in Calcutta were not passed down.

Bengali was my first language, what I spoke and heard at home. Bo1 the books of my childhood were in English, and their subjects for the most part, were either English or American lives. I was aware of a feeling of trespassing; I was aware that I did not belong to the worlds I was reading about: that different food graced our table, that different holidays were celebrated. And yet when a book was in my possession, this didn't matter.

As a young girl, I was afraid to participate in social activities. I was worried about what others might make of me. But when l read I was free of this worry. I learned what my fictional companions ate and wore, about the toys scattered in their rooms, the vacations they took, the jams their mothers stirred on the stove. For me, the act of reading was one of discovery in the most basic sense-the discovery of a culture that was foreign to my parents.

When I began to make friends, writing was the vehicle to write not alone but with another student in my class. We would sit together, dreaming up characters and plots, taking turns writing sections of the story. The stories were transparent riffs on what I was reading at the time: families living on prairies, orphaned girls sent off to boarding schools, children with supernatural powers.

As I grew into adolescence and beyond, however, my writing shrank. Though the compulsion to invent stories remained, self-doubt began to undermine   it. What I loved at seven becao1e, by seventeen, the form of self -expression that most intimidated me. Al twenty one, the writer in me was like a fly in the room- alive but insignificant, aimless, something that unsettled me whenever I grew aware of it.

After I graduated from college, I moved to Boston and formed a close friendship with a young woman whose father is a poet named Bill Corbett. I began to visit the Corbetts' home, which was filled with books and art. I saw the desk where Bill wrote, obscured by manuscripts, letters, and proofs. J saw that the work taking place on this desk was obliged to no one, connected to no institution; that this desk was an island. I spent a summer pecking out sketches and fragments on a typewriter.

I began to want to be a writer. Secretly at first, exchanging pages with one other person, our pre scheduled meetings forced me to sit down and produce something.

I worked up the nerve to apply for a formal spot in a creative-writing program. When I told my parents that I'd been accepted, with a fellow’s hip, they neither encouraged nor discouraged me. Like so many aspects of my American life, the idea that one could get a degree in creative writing, that it could be a legitimate course of study, seemed perhaps frivolous to them.

As a child, I had written to connect with my peers. But when I started writing stories again, in my twenties, my parents were the people I was struggling to reach. In 1992, just before starting the writing program, l went to Calcutta with my family. I remember coming back at the end of summer and almost immediately writing the first of the stories I submitted that year in a workshop. It was set in the building where my mother had grown up, and where I spent much of my time when I was in India. I see now that my impulse to write this story was to prove something to my parents: that I understood, in a limited but precise way, the world they came from.

For much of my life, I was warned to belong to a place, either the one my parents came from or to America. When I became a writer my desk became home; there was no need for another. I belong to my work, to my characters.

SOCIAL SCIENCE: This passage is adapted from the book Brave Companions: Portraits In History by David McCullough (01992 by David McCullough).

It was not long after the completion of the Panama Railroad in 1855 that Bedford Clapperton Pim declared with perfect composure that of all the world's wonders none could surpass this one as a demonstration of s man's capacity to do great things against impossible odds.

"I have seen the greatest engineering works of the day," he wrote, ". . . but I must confess that when passing backward and forwards on the Panama Railway, I have never been more struck than with me evidence, apparent on every side, of the wonderful skill, endurance, and perseverance, which must have been exercised in its construction."

Bedford Clappercon Pim was a British naval officer and of no particular historical significance. He had, however, seen a great deal of the world, he was a recognized authority on Cemrill America, and his opinion was not lightly arrived at.

It should be kept in mind that the first railroads , all very primitive, had been built in Europe and the United States only some twenty years before. France was still virtually without railroads; not a rail had been put down west of the Mississippi as yet. Moreover, such awesome technological strides as the Suez Canal, the Union Pacific, and the Brooklyn Bridge were still well in to the future. And so the vision of locomotives highballing through the green half-light of some distant rain forest, of the world's two greatest oceans joined by good English-made rails, could stir the blood to an exceptional degree.

The Panama Railroad was begun in J 850, at the height of the California gold craze. And by anyone's standards it was a stunning demonstration of man's "wonderful skill, endurance, and perseverance” just as Pim said, even though its full length was only forty seven and a half miles. It was, for example, the first ocean-to-ocean railroad, Mile for mile it also appears to have cost more in dollars and in human life than any railroad ever built.

The surveys made by its builders produced important geographic revelations that had a direct bearing on the decision to build a Panama Canal along the same route. In addition, the diplomatic agreement upon which the whole venture rested, the so-called Bidlack Treaty of 1846, was the basis of all subsequent involvement of the United States in Panama.

Still, the simple fact that it was built remains the overriding wonder, given the astonishing difficulties that had to be overcome and the means at band in the 1850s. Present-day engineers   who have had experience in jungle construction wonder how in the world it was ever managed. I think in particular of David S. Parker, an eminent army engineer whom I interviewed at the time he was governor of the Canal Zone. Through a great sweep of glass behind him, as we talked, were the distant bills of Panama, no different in appearance than they ever were. It is almost inconceivable, be said, that the railroad survey- just the survey- could have been made by a comparative handful of men who bad no proper equipment for topographic reconnaissance (no helicopters, no recourse to aerial photography), no modern medicines, nor the least understanding of the causes of malaria or yellow fever. There was no such thing as an insect repellent, no bulldozers, no chain saws, no canned goods, not one reliable map.

A Panama railroad still crosses from the Atlantic to the Pacific, from Colon lo Panama City. Much of the ride- especially if you are in one of the older cars (without air conditioning, windows open wide) - looks and feels as it must have originally. The full trip takes one hour and thirty minutes. But except for a few miles at either end, the present line is altogether different from the original. It takes a different route on higher ground. The old road has vanished beneath Gatun Lake, the enormous body of freshwater that comprises most of the canal and that can be seen close by on the right much of the way as you head toward the Pacific.

The original line was built as hurriedly and cheaply as circumstances would allow, to take advantage of the bonanza in California traffic. The route was always along the line of least resistance. Anything formidable in the way-a hill, a bend in the Cbagres River-was bypassed if possible. No tunnels were attempted (there is one on the present line), and the winding right of way chopped through the jungle was just wide enough to let a train pass. Still this one little stretch of  track took nearly five years to build and cost $8 million, which averages out to a little less than ten miles a year and a then unheard-of $168,000 per mile.

Passage III

HUMANITIES: Passage A is adapted from the essay' Henry D. Thoreau" by John Burroughs (@1882 by The Century Co.). Passage B Is adapted from tile essay "Qualified Homage 10 Thoreau• b9 Wallace Stegner (©1892 by the Estala of Wallace Stegner). 

Passage A by John Burroughs

Thoreau’s fame has steadily increased since his death, in I862, as it was bound to do. It was little more than in the bud at that time, and its fall leaf and flowering are not yet, perhaps not in many years yet. He improves with age; in fact, requires age to take off a little of his asperity and fully ripen him. The generation he lectured so sharply will not give the same heed to his words as will the next and the next. The first effect of the reading of his books, upon many minds, is irritation and disapproval; the perception of their beauty and wisdom comes later. He was a man devoid of compassion, devoid of sympathy, devoid of generosity, devoid of patriotism, as 'these words are usually understood, yet his life showed a devotion to principle such as one life in millions does not show; and matching his there rush through his works a vein of the purest and rarest poetry and the finest wisdom for both these reasons time will enhance rather than lessen the value of his contributions. The world likes a good hater and refuser almost as well as it likes a good lover and acceptor, only it likes him farther off.

In writing of Thoreau, I am not conscious of having any criticism to make of him, l would fain accept him just as he was, and make the most of him, defining and discriminating him as I  would a flower or a bird or any other product of nature- perhaps exaggerating some features the better to bring cbcm out. I suppose there were greater men among his contemporaries, but I doubt if there were any more genuine and sincere, or more devoted to ideal ends. If he was not this, that, or the other great man, he was Thoreau, and he fills his own niche well, and has left a positive and distinct impression upon the literature of his country. He was, perhaps, a little too near his friend and master, Emerson, and brought too directly under his influence. But the contour of his moral nature was just as firm and resisting. He was no more a soft-shelled egg, to be dented by every straw in the nest, than was his distinguished neighbor.

Passage B by Wallace Stegner

Walden Woods is the 2,680-acre area outside Boston, Massachusetts that inspired Thoreau's book Walden.

Before I get around to saying why I think that Walden Woods absolutely must be preserved from subdivision   and   development, let me confess that, much as I admire Thoreau's bard-mouthed intellectual integrity and his knotty grappler's mind, I have some reservations about him. There are writings of his that I admire more than Walden-the essay "Walking," for example, which is superb from first line to last, and "Civil Disobedience," though this latter is as explosive as dynamite caps, and should not be left around where children might find ii and play with it Reading Walden., I am alternately exhilarated and exasperated, as some of the author's contemporaries were with the man himself. In one paragraph he may say something that has been waiting a thousand years to be said so well; in the next he is capable of something so outrageous that it sets my teeth on edge.

With the Thoreau who observed and participated in nature, the Thoreau who loved wildness, and the Thoreau who trusted physical labor so long as it was not a compulsion, and who mistrusted material ambition, I am completely in accord. lt is Thoreau the moralizing enemy of the tradition to which he owes all his own authority who puts me off.

Like any zealot, he is intemperate. All times be 65 sounds perilously like his spiritual descendants of the 1960s, who trusted no one over thirty and believed that they existed outside of, and were exempt from, the society they were protesting. What  I miss in him,  as  I missed it in the more extreme rebels of the J 960s, is the acknowledgment that their society shaped them, that without it every individual of them would be a sort of Sasquatch, a solitary animal without language, thought, tradition, obligation, or commitment. It is culture, tradition, that teaches us to be human, teaches us almost everything, including how I protest and what to protest about.

I never hear Thoreau admitting this- in fact, he often specifically denies ii, and his denials raise my temperature. "How about a little well-deserved humility?" I feel like asking him. It is like arguing with a television screen, but it eases the mind.

The fact is, it is precisely Thoreau's repudiation of the dead band of the past that makes him so excruciatingly American. He pretends to believe that all experience is not merely fruitless, but damaging. "Men think they are wiser by experience, that is, by failure," he remarks in Walden. “l have always been regretting Until was not as wise as the day I was born."

NATURAL SCIENCE: This passage is adapted from the article "Molecular Evolution" by Tina Hesman Saey (©2009 by Society for Science & the Public).

Richard Lenski, an evolutionary biologist,is among the scientists hitting the rewind button on evolution. Meter-high letters taped to the window of his lab spell out the lab's motto: EVOLVE.

Inside the lab, a dozen glass flasks containing clear liquid swirl in a temperature-controlled incubator. Although the naked eye can’t see them, millions of C. coli bacteria grow in the flasks, doing what the window exhorts. Lenski started the cultures in 1988, intending to follow the course of natural selection for several hundred generations. Now, two decades later, the cultures are still growing and have produced more than 45,000 generations of bacteria each.

These flasks "represent the stripped-down bare essentials of evolution," says Zachary Blount, a graduate student in Lenski's lab. The environment never changes. No new genes enter the system from migrating microorganisms.   And the scientists take no action to affect the course of evolution within the flasks. Only the intrinsic, core processes of evolution influence the outcome, Blount says.

Lenski and his colleagues have watched the gameplay out, occasionally analyzing DNA to peer over the players' shoulders and find out what cards they hold. On the surface, the populations in the 12 flasks seem to have traveled similar paths- all now grow larger cells and have become more efficient at using glucose than their ancestors. And many of the strains have accumulated mutations in the same genes. Notably, though, none of the strains developed exactly the same genetic changes.

Randomness is an important part of the evolutionary equation, as the experiment illustrates. During the first 2,000 generations, all of the populations rapidly increased in size and fitness. But then these changes began to slow down, biting the evolutionary equivalent of a dieter's plateau.

After 10,000 generations, it became apparent that not all the flasks were on the same trajectory. Though cells in all the flasks became larger, each population differed in the maximum size the cells reached. The populations also differed in how much finer they were than their ancestors, when grown in direct competition. Several of the flasks now contain mutator strains, bacteria that have defects in their DNA replication system. Such defects make mistakes more likely to happen every time those bacterial strains copy their DNA 10 divide. Sometimes a mistake can have lethal consequences, damaging a gene crucial for survival. But other times coloring a bit outside the lines creates opportunity for advancement

Even within a given flask, some bacteria take slightly different paths. One flask now contains two separate strains-one that makes large colonies when grown on petri dishes, and one that makes small colonies. The large- and small-colony strains have coexisted for more than 12,000 generations.

The large colony producers are much better at using glucose so they grow quickly, but they make by-products that the small-colony producers can eat. 'Both strains have increased in fitness over the generations. Still, though the details were different, replaying evolution in a dozen flasks produced very similar outcomes in each.

But then something completely unexpected happened. After about 31, 5 00 generations, glucose-eating bacteria in one flask suddenly developed the ability to eat a chemical called citrate, something no other E.coli do. .

The switch was clearly a radical change of destination for the bacteria. The inability to eat citrate is a biochemical hallmark of the E. coli species, so by some definitions, the citrate eaters in that flask are no longer E.coli.

But a single change did not a citrate eater make. The researchers found that the bacteria went through a series of steps before evolving the ability to use citrate. One initial mutation happened at least 11,000 generations before the citrate eaters appeared. Lenski doesn’t yet know which specific DNA changes led to citrate use, but it's clear that the ability to use citrate is contingent upon those earlier changes. And even bacteria that have undergone those initial changes are still not guaranteed to eat citrate. Blount tested 40 trillion bacteria from earlier generations to see if any could evolve the ability to eat citrate. Fewer than one in a trillion could.

The profound difference between the citrate caters and the other 11 strains, as well as the dependence of the citrate change on earlier mutations, is to suggest that replaying evolution will result in some surprise endings.