An individual nerve cell may be up to ........... long. ?->(Show Answer!)

1. An individual nerve cell may be up to ........... long.

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MCQ-> The membrane-bound nucleus is the most prominent feature of the eukaryotic cell. Schleiden and Schwann, when setting forth the cell doctrine in the 1830s, considered that it had a central role in growth and development. Their belief has been fully supported even though they had only vague notions as to what that role might be, and how the role was to be expressed in some cellular action. The membraneless nuclear area of the prokaryotic cell, with its tangle of fine threads, is now known to play a similar role.Some cells, like the sieve tubes of vascular plants and the red blood cells of mammals, do not possess nuclei during the greater part of their existence, although they had nuclei when in a less differentiated state. Such cells can no longer divide and their life span is limited Other cells are regularly multinucleate. Some, like the cells of striated muscles or the latex vessels of higher plants, become so through cell fusion. Some, like the unicellular protozoan paramecium, are normally binucleate, one of the nuclei serving as a source of hereditary information for the next generation, the other governing the day-to-day metabolic activities of the cell. Still other organisms, such as some fungi, are multinucleate because cross walls, dividing the mycelium into specific cells, are absent or irregularly present. The uninucleate situation, however, is typical for the vast majority of cells, and it would appear that this is the most efficient and most economical manner of partitioning living substance into manageable units. This point of view is given credence not only by the prevalence of uninucleate cells, but because for each kind of cell there is a ratio maintained between the volume of the nucleus and that of the cytoplasm. If we think of the nucleus as the control centre of the cell, this would suggest that for a given kind of cell performing a given kind of work, one nucleus can ‘take care of’ a specific volume of cytoplasm and keep it in functioning order. In terms of material and energy, this must mean providing the kind of information needed to keep flow of materials and energy moving at the correct rate and in the proper channels. With the multitude of enzymes in the cell, materials and energy can of course be channelled in a multitude of ways; it is the function of some information molecules to make channels of use more preferred than others at any given time. How this regulatory control is exercised is not entirely clear.The nucleus is generally a rounded body. In plant cells, however, where the centre of the cell is often occupied by a large vacuole, the nucleus may be pushed against the cell wall, causing it to assume a lens shape. In some white blood cells, such as polymorphonucleated leukocytes, and in cells of the spinning gland of some insects and spiders, the nucleus is very much lobed The reason for this is not clear, but it may relate to the fact that for a given volume of nucleus, a lobate form provides a much greater surface area for nuclear-cytoplasmic exchanges, possibly affecting both the rate and the amount of metabolic reactions. The nucleus, whatever its shape, is segregated from the cytoplasm by a double membrane, the nuclear envelope, with the two membranes separated from each other by a perinuclear space of varying width. The envelope is absent only during the time of cell division, and then just for a brief period The outer membrane is often continuous with the membranes of the endoplasmic reticulum, a possible retention of an earlier relationship, since the envelope, at least in part, is formed at the end cell division by coalescing fragments of the endoplasmic reticulum. The cytoplasmic side of the nucleus is frequently coated with ribosomes, another fact that stresses the similarity and relation of the nuclear envelope to the endoplasmic reticulum. The inner membrane seems to posses a crystalline layer where it abuts the nucleoplasm, but its function remains to be determined.Everything that passes between the cytoplasm and the nucleus in the eukaryotic cell must transverse the nuclear envelope. This includes some fairly large molecules as well as bodies such as ribosomes, which measure about 25 mm in diameter. Some passageway is, therefore, obviously necessary since there is no indication of dissolution of the nuclear envelope in order to make such movement possible. The nuclear pores appear to be reasonable candidates for such passageways. In plant cells these are irregularly, rather sparsely distributed over the surface of the nucleus, but in the amphibian oocyte, for example, the pores are numerous, regularly arranged, and octagonal and are formed by the fusion of the outer and inner membrane.Which of the following kinds of cells never have a nuclei?
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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-> Question Numbers: (55 to 58)In a square layout of site 5m ~ 5m 25 equal-sized square platforms of different heights are built. The heights (in metre) of individual platforms are as shown below:

Individuals (all of same height) are seated on these platforms. We say an individual A can reach individual B, if all the three following conditions are met; (i) A and B are In the same row or column (ii) A is at a lower height than B (iii) If there is/are any individuals (s) between A and B, such individual(s) must be at a height lower than that of A. Thus in the table given above, consider the Individual seated at height 8 on 3rd row and 2nd column. He can be reached by four individuals. He can be reached by the individual on his left at height 7, by the two individuals on his right at heights of 4 and 6 and by the individual above at height 5. How many individuals in this layout can be reached by just one individual?
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MCQ-> Answer questions based on the following information: An automobiles company’s annual sales of its small cars depends on the state of the economy as well as on whether the company uses some high profile individual as its brand ambassador in advertisements of its product. The state of the economy is “good”, “okay” and “bad” with probabilities 0.3, 0.4 and 0.3 respectively. The company may choose a high profile individual as its brand ambassador in TV ads or may go for the TV ads without a high profile brand ambassador. If the company fixes price at Rs. 3.5 lakh, the annual sales of its small cars for different states of the economy and for different kinds of TV ads are summarized in table 1. The figures in the first row are annual sales of the small cars when the company uses a high profile individual as its brand ambassador in its TV ads and the ones in the second row are that when the company does not use any brand ambassador in TV ads, for different states of the economy. Table 1:

Without knowing what exactly will be the state of the company in the coming one year, the company will either have to sign a TV ad contract with some high profile individual, who will be the company’s brand ambassador for its small car for the next one year, or go for a TV ad without featuring any high profile individual. It incurs a cost of Rs. 3.45 lakh (excluding the payment to the brand ambassador) to put a car on the road. When the company’s profit is uncertain, the company makes decisions on basis of its expected profit. If the company can earn a profit xi with probability pi (the probability depends on the state of economy), then the expected profit of the company is $$\sum_1XiPi$$The maximum that the company can afford to pay its brand ambassador is
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MCQ-> Read the following passage carefully and answer the questions given below it. Certain words/phrases have been printed in bold tohelp you locate them while answering some of the questions. During the last few years, a lot of hype has been heaped on the BRICS (Brazil, Russia, India, China, and South Africa). With their large populations and rapid growth, these countries, so the argument goes, will soon become some of the largest economies in the world and, in the case of China, the largest of all by as early as 2020. But the BRICS, as well as many other emerging-market economieshave recently experienced a sharp economic slowdown. So, is the honeymoon over? Brazil’s GDP grew by only 1% last year, and may not grow by more than 2% this year, with its potential growth barely above 3%. Russia’s economy may grow by barely 2% this year, with potential growth also at around 3%, despite oil prices being around $100 a barrel. India had a couple of years of strong growth recently (11.2% in 2010 and 7.7% in 2011) but slowed to 4% in 2012. China’s economy grew by 10% a year for the last three decades, but slowed to 7.8% last year and risks a hard landing. And South Africa grew by only 2.5% last year and may not grow faster than 2% this year. Many other previously fast-growing emerging-market economies – for example, Turkey, Argentina, Poland, Hungary, and many in Central and Eastern Europe are experiencing a similar slowdown. So, what is ailing the BRICS and other emerging markets? First, most emerging-market economies were overheating in 2010-2011, with growth above potential and inflation rising and exceeding targets. Many of them thus tightened monetary policy in 2011, with consequences for growth in 2012 that have carried over into this year. Second, the idea that emerging-market economies could fully decouple from economic weakness in advanced economies was farfetched : recession in the eurozone, near-recession in the United Kingdom and Japan in 2011-2012, and slow economic growth in the United States were always likely to affect emerging market performance negatively – via trade, financial links, and investor confidence. For example, the ongoing euro zone downturn has hurt Turkey and emergingmarket economies in Central and Eastern Europe, owing to trade links. Third, most BRICS and a few other emerging markets have moved toward a variant of state capitalism. This implies a slowdown in reforms that increase the private sector’s productivity and economic share, together with a greater economic role for state-owned enterprises (and for state-owned banks in the allocation of credit and savings), as well as resource nationalism, trade protectionism, import substitution industrialization policies, and imposition of capital controls. This approach may have worked at earlier stages of development and when the global financial crisis caused private spending to fall; but it is now distorting economic activity and depressing potential growth. Indeed, China’s slowdown reflects an economic model that is, as former Premier Wen Jiabao put it, “unstable, unbalanced, uncoordinated, and unsustainable,” and that now is adversely affecting growth in emerging Asia and in commodity-exporting emerging markets from Asia to Latin America and Africa. The risk that China will experience a hard landing in the next two years may further hurt many emerging economies. Fourth, the commodity super-cycle that helped Brazil, Russia, South Africa, and many other commodity-exporting emerging markets may be over. Indeed, a boom would be difficult to sustain, given China’s slowdown, higher investment in energysaving technologies, less emphasis on capital-and resource-oriented growth models around the world, and the delayed increase in supply that high prices induced. The fifth, and most recent, factor is the US Federal Reserve’s signals that it might end its policy of quantitative easing earlier than expected, and its hints of an even tual exit from zero interest rates. both of which have caused turbulence in emerging economies’ financial markets. Even before the Fed’s signals, emergingmarket equities and commodities had underperformed this year, owing to China’s slowdown. Since then, emerging-market currencies and fixed-income securities (government and corporate bonds) have taken a hit. The era of cheap or zerointerest money that led to a wall of liquidity chasing high yields and assets equities, bonds, currencies, and commodities – in emerging markets is drawing to a close. Finally, while many emerging-market economies tend to run current-account surpluses, a growing number of them – including Turkey, South Africa, Brazil, and India – are running deficits. And these deficits are now being financed in riskier ways: more debt than equity; more short-term debt than longterm debt; more foreign-currency debt than local-currency debt; and more financing from fickle cross-border interbank flows. These countries share other weaknesses as well: excessive fiscal deficits, abovetarget inflation, and stability risk (reflected not only in the recent political turmoil in Brazil and Turkey, but also in South Africa’s labour strife and India’s political and electoral uncertainties). The need to finance the external deficit and to avoid excessive depreciation (and even higher inflation) calls for raising policy rates or keeping them on hold at high levels. But monetary tightening would weaken already-slow growth. Thus, emerging economies with large twin deficits and other macroeconomic fragilities may experience further downward pressure on their financial markets and growth rates. These factors explain why growth in most BRICS and many other emerging markets has slowed sharply. Some factors are cyclical, but others – state capitalism, the risk of a hard landing in China, the end of the commodity supercycle -are more structural. Thus, many emerging markets’ growth rates in the next decade may be lower than in the last – as may the outsize returns that investors realised from these economies’ financial assets (currencies, equities. bonds, and commodities). Of course, some of the better-managed emerging-market economies will continue to experitnce rapid growth and asset outperformance. But many of the BRICS, along with some other emerging economies, may hit a thick wall, with growth and financial markets taking a serious beating.Which of the following statement(s) is/are true as per the given information in the passage ? A. Brazil’s GDP grew by only 1% last year, and is expected to grow by approximately 2% this year. B. China’s economy grew by 10% a year for the last three decades but slowed to 7.8% last year. C. BRICS is a group of nations — Barzil, Russia, India China and South Africa.....