1. Fire : Burn : : Water : ?





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MCQ-> Cells are the ultimate multi-taskers: they can switch on genes and carry out their orders, talk to each other, divide in two, and much more, all at the same time. But they couldn’t do any of these tricks without a power source to generate movement. The inside of a cell bustles with more traffic than Delhi roads, and, like all vehicles, the cell’s moving parts need engines. Physicists and biologists have looked ‘under the hood’ of the cell and laid out the nuts and bolts of molecular engines.The ability of such engines to convert chemical energy into motion is the envy nanotechnology researchers looking for ways to power molecule-sized devices. Medical researchers also want to understand how these engines work. Because these molecules are essential for cell division, scientists hope to shut down the rampant growth of cancer cells by deactivating certain motors. Improving motor-driven transport in nerve cells may also be helpful for treating diseases such as Alzheimer’s, Parkinson’s or ALS, also known as Lou Gehrig’s disease.We wouldn’t make it far in life without motor proteins. Our muscles wouldn’t contract. We couldn’t grow, because the growth process requires cells to duplicate their machinery and pull the copies apart. And our genes would be silent without the services of messenger RNA, which carries genetic instructions over to the cell’s protein-making factories. The movements that make these cellular activities possible occur along a complex network of threadlike fibers, or polymers, along which bundles of molecules travel like trams. The engines that power the cell’s freight are three families of proteins, called myosin, kinesin and dynein. For fuel, these proteins burn molecules of ATP, which cells make when they break down the carbohydrates and fats from the foods we eat. The energy from burning ATP causes changes in the proteins’ shape that allow them to heave themselves along the polymer track. The results are impressive: In one second, these molecules can travel between 50 and 100 times their own diameter. If a car with a five-foot-wide engine were as efficient, it would travel 170 to 340 kilometres per hour.Ronald Vale, a researcher at the Howard Hughes Medical Institute and the University of California at San Francisco, and Ronald Milligan of the Scripps Research Institute have realized a long-awaited goal by reconstructing the process by which myosin and kinesin move, almost down to the atom. The dynein motor, on the other hand, is still poorly understood. Myosin molecules, best known for their role in muscle contraction, form chains that lie between filaments of another protein called actin. Each myosin molecule has a tiny head that pokes out from the chain like oars from a canoe. Just as rowers propel their boat by stroking their oars through the water, the myosin molecules stick their heads into the actin and hoist themselves forward along the filament. While myosin moves along in short strokes, its cousin kinesin walks steadily along a different type of filament called a microtubule. Instead of using a projecting head as a lever, kinesin walks on two ‘legs’. Based on these differences, researchers used to think that myosin and kinesin were virtually unrelated. But newly discovered similarities in the motors’ ATP-processing machinery now suggest that they share a common ancestor — molecule. At this point, scientists can only speculate as to what type of primitive cell-like structure this ancestor occupied as it learned to burn ATP and use the energy to change shape. “We’ll never really know, because we can’t dig up the remains of ancient proteins, but that was probably a big evolutionary leap,” says Vale.On a slightly larger scale, loner cells like sperm or infectious bacteria are prime movers that resolutely push their way through to other cells. As L. Mahadevan and Paul Matsudaira of the Massachusetts Institute of Technology explain, the engines in this case are springs or ratchets that are clusters of molecules, rather than single proteins like myosin and kinesin. Researchers don’t yet fully understand these engines’ fueling process or the details of how they move, but the result is a force to be reckoned with. For example, one such engine is a spring-like stalk connecting a single-celled organism called a vorticellid to the leaf fragment it calls home. When exposed to calcium, the spring contracts, yanking the vorticellid down at speeds approaching three inches (eight centimetres) per second.Springs like this are coiled bundles of filaments that expand or contract in response to chemical cues. A wave of positively charged calcium ions, for example, neutralizes the negative charges that keep the filaments extended. Some sperm use spring-like engines made of actin filaments to shoot out a barb that penetrates the layers that surround an egg. And certain viruses use a similar apparatus to shoot their DNA into the host’s cell. Ratchets are also useful for moving whole cells, including some other sperm and pathogens. These engines are filaments that simply grow at one end, attracting chemical building blocks from nearby. Because the other end is anchored in place, the growing end pushes against any barrier that gets in its way.Both springs and ratchets are made up of small units that each move just slightly, but collectively produce a powerful movement. Ultimately, Mahadevan and Matsudaira hope to better understand just how these particles create an effect that seems to be so much more than the sum of its parts. Might such an understanding provide inspiration for ways to power artificial nano-sized devices in the future? “The short answer is absolutely,” says Mahadevan. “Biology has had a lot more time to evolve enormous richness in design for different organisms. Hopefully, studying these structures will not only improve our understanding of the biological world, it will also enable us to copy them, take apart their components and recreate them for other purpose.”According to the author, research on the power source of movement in cells can contribute to
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MCQ-> Read the following passage carefully and answer the questions given at the end.The tight calendar had calmed him, as did the constant exertion of his authority as a judge. How he relished his power over the classes that had kept his family pinned under their heels for centuries - like the stenographer, for example, who was a Brahmin. There he was, now crawling into a tiny tent to the side, and there was Jemubhai reclining like a king in a bed carved out of teak, hung with mosquito netting."Bed tea", the cook would shout "Baaad tee". He would sit up to drink.6:30: he'd bathe in water that had been heated over the fire so it was redolent with the smell of wood smoke and flecked with ash. With a dusting of powder he graced his newly washed face, with a daub of pomade, his hair. Crunched up toast like charcoal from having been toasted upon the flame, with marmalade over the burn.8:30: he rode into the fields with the local officials and everyone else in the village going along for fun. Followed by an orderly holding an umbrella over his head to shield him from the glare, he measured the fields and checked to make sure his yield estimate matched the headman's statement. Farms were growing less than ten maunds an acre of rice or wheat, and at two rupees a maund, every single man in a village, sometimes, was in debt to the bania. (Nobody knew that Jemubhai himself was noosed, of course, that long ago in the little town of Piphit in Gujarat, money-lenders had sniffed out in him a winning combination of ambition and poverty ... that they still sat waiting cross-legged on a soiled mat in the market, snapping their toes, cracking their knuckles in anticipation of repayment .... ) 2.00: after lunch, the judge sat at his desk under a tree to try cases, usually in a cross mood, for he disliked the informality, hated the splotch of leaf shadow on him imparting an untidy mongrel look. Also, there was a worse aspect of contamination and corruption: he heard cases in Hindi, but they were recorded in Urdu by the stenographer and translated by the judge into a second record in English, although his own command of Hindi and Urdu was tenuous; the witnesses who couldn't read at all put their thumbprints at the bottom of "Read Over and Acknowledged Correct", as instructed. Nobody could be sure how much of the truth had fallen between languages, between languages and illiteracy; the clarity that justice demanded was nonexistent. Still, despite the leaf shadow and language confusion, he acquired a fearsome reputation for his speech that seemed to belong to no language at all, and for his face like a mask that conveyed something beyond human fallibility. The expression and manner honed here would carry him, eventually, all the way to the high court in Lucknow where, annoyed by lawless pigeons shuttlecocking about those tall, shadowy halls, he would preside, white powdered wig over white powdered face, hammer in hand.His photograph, thus attired, thus annoyed, was still up on the wall, in a parade of history glorifying the progress of Indian law and order. 4:30: tea had to be perfect, drop scones made in the frying pan. He would embark on them with forehead wrinkled, as if angrily mulling over something important, and then, as it would into his retirement, the draw of the sweet took over, and his stern work face would hatch an expression of tranquillity.5:30: out he went into the countryside with his fishing rod or gun. The countryside was full of game; lariats of migratory birds lassoed the sky in October; quail and partridge with lines of babies strung out behind whirred by like nursery toys that emit sound with movement; pheasant - fat foolish creatures, made to be shot - went scurrying through the bushes. The thunder of gunshot roiled away, the leaves shivered, and he experienced the profound silence that could come only after violence. One thing was always missing, though, the proof of the pudding, the prize of the action. the manliness in manhood, the partridge for the pot. because he returned with - Nothing!He was a terrible shot.8:00: the cook saved his reputation, cooked a chicken, brought it forth, proclaimed it "roast bastard", just as in the Englishman's favourite joke book of natives using incorrect English. But sometimes, eating that roast bustard, the judge felt the joke might also be on him, and he called for another rum, took a big gulp, and kept eating feeling as if he were eating himself, since he, too, was (was he?) part of the fun ....9:00: sipping Ovaltine, he filled out the registers with the day's gleanings. The Petromax lantern would be lit - what a noise it made - insects fording the black to dive - bomb him with soft flowers (moths), with iridescence (beetles). Lines, columns, and squares. He realized truth was best looked at in tiny aggregates, for many baby truths could yet add up to one big size unsavory lie. Last, in his diary also to be submitted to his superiors, he recorded the random observations of a cultured man, someone who was observant, schooled in literature as well as economics; and he made up hunting triumphs: two partridge ... one deer with thirty- inch horns....11:00: he had a hot water bottle in winter, and, in all seasons, to the sound of the wind buffeting the trees and the cook's snoring, he fell asleep.Which of the following statements is incorrect?
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MCQ->Which of the following statement(s) is/are INCORRECT ? I. Alkenes are fairly unreactive. II. Alkenes burn with blue flame. III. Alkanes burn with yellow flame.....
MCQ-> Read the following caselet and choose the best alternative: Head of a nation in the Nordic region was struggling with the slowing economy on one hand and restless citizens on the other. In addition, his opponents were doing everything possible to discredit his government. As a famous saying goes, "There is no smoke without a fire", it cannot be said that the incumbent government was doing all the right things. There were reports of acts of omission and commission coming out every other day. Distribution of public resources for private businesses and for private consumption had created a lot of problems for the government. It was being alleged that the government has given the right to exploit these public resources at throw-away prices to some private companies. Some of the citizens were questioning the government policies in the Supreme Court of the country as well as in the media. In the midst of all this, the head of the nation called his cabinet colleagues for a meeting on the recent happenings in the country. He asked his minister of water resources about the bidding process for allocation of rights to setup mini-hydel power plants. To this, the minister replied that his ministry had followed the laid out policies of the government. Water resources were allocated to those private companies that bid the highest and were technically competent. The minister continued that later on some new companies had shown interest and they were allowed to enter the sector as per the guidelines of the Government. This, the minister added, would facilitate proper utilization of water resources and provide better services to the citizens. The new companies were allocated the rights at the price set by the highest bidders in the previous round of bidding. After hearing this, the head of the nation that one would expect the later allocations to be done after a fresh round of bidding. The minister of water resources replied that his ministry had taken permissions from the concerned ministries before allocating the resources to the new companies.Media reports suggested that the minister of water resources had deliberately allocated the water resources at old prices to the new companies, and in return some received kickbacks. However, the minister denied these charges. His counter argument was that he followed the stated policies of the Government and it is very difficult to price a scarce resource. He also said that the loss that the media is talking about is notional and in reality the Government and the citizens have gained by the entry of new players. Which of the following is the most appropriate inference?
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MCQ->Fire : Burn : : Water : ?....
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