Force between the molecules of the same substance is called _________

1. Force between the molecules of the same substance is called __________ force.

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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 passages carefully and answer the questions given at the end of each passage.PASSAGE 3Typically women participate in the labour force at a very high rate in poor rural countries. The participation rate then falls as countries industrialise and move into the middle income class. Finally, if the country grows richer still, more families have the resources for higher education for women and from there they often enter the labour force in large numbers. Usually, economic growth goes hand in hand with emancipation of women. Among rich countries according to a 2015 study, female labour force participation ranges from nearly 80 percent in Switzerland to 70 percent in Germany and less than 60 Percent in the United States and Japan. Only 68 Percent of Canadian omen participated in the workforce in 1990; two decades later that increased to 74 Percent largely due to reforms including tax cuts for second earners and new childcare services. In Netherlands the female labour participation rate doubled since 1980 to 74 Percent as a result of expanded parental leave policies and the spread of flexible, part time working arrangements. In a 2014 survey of 143 emerging countries, the World Bank found that 90 Percent have at least one law that limits the economic opportunities available to women. These laws include bans or limitations on women owning property, opening a bank account, signing a contract, entering a courtroom, travelling alone, driving or controlling family finances. Such restrictions are particularly prevalent in the Middle East and South Asia with the world’s lowest female labour force participation, 26 and 35 percent respectively. According to date available with the International Labour Organisation (ILO), between 2004 and 2011, when the Indian economy grew at a healthy average of about 7 percent, there was a decline in female participation in the country’s labour force from over 35 percent to 25 percent. India also posted the lowest rate of female participation in the workforce among BRIC countries. India’s performance in female workforce participation stood at 27 percent, significantly behind China (64 percent), Brazil (59 percent), Russian Federation (57 percent), and South Africa (45 percent). The number of working women in India had climbed between 2000 and 2005, increasing from 34 percent to 37 percent, but since then the rate of women in the workforce has to fallen to 27 percent as of 2014, said the report citing data from the World Bank. The gap between male and female workforce participation in urban areas in 2011 stood at 40 percent, compared to rural areas where the gap was about 30 percent. However, in certain sectors like financial services, Indian women lead the charge. While only one in 10 Indian companies are led by women, more than half of them are in the financial sector. Today, women head both the top public and private banks in India. Another example is India’s aviation sector, 11.7 percent of India’s 5,100 pilots are women, versus 3 percent worldwide. But these successes only represent a small of women in the country. India does poorly in comparison to its neighbours despite a more robust economic growth. In comparison to India, women in Bangladesh have increased their participation in the labour market, which is due to the growth of the ready- made garment sector and a push to rural female employment. In 2015, women comprised of 43 percent of the labour force in Bangladesh. The rate has also increased in Pakistan, albeit from a very low starting point, while participation has remained relatively stable in Sri Lanka. Myanmar with 79 percent and Malaysia with 49 percent are also way ahead of India. Lack of access to higher education, fewer job opportunities, the lack of flexibility in working conditions, as well as domestic duties are cited as factors behind the low rates. Marriage significantly reduced the probability of women working by about 8 percent in rural areas and more than twice as much in urban areas, said an Assocham report. ILO attributes this to three factors: increasing educational enrolment, improvement in earning of male workers that discourage women’s economic participation, and lack of employment opportunities at certain levels of skills and qualifications discouraging women to seek work. The hurdles to working women often involve a combination of written laws and cultural norms. Cultures don’t change overnight but laws can. The IMF says that even a small step such as countries granting women the right to open a bank account can lead to substantial increase in female labour force participation over the next seven years. According to the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP), even a 10 percent increase in women participating in the workforce can boost gross domestic product (GDP) by 0.3 percent. The OECD recently estimated that eliminating the gender gap would lead to an overall increase in GDP of 12 percent in its member nations between 2015 and 2030. The GDP gains would peak close to 20 percent in both Japan and South Korea and more than 20 percent in Italy. A similar analysis by Booz and Company showed that closing gender gap in emerging countries could yield even larger gains in GDP by 2020, ranging from a 34 percent gain in Egypt to 27 percent in India and 9 percent in Brazil. According to the above passage, though there are many reasons for low female labour force participation, the most important focus of the passage is on
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MCQ-> Read the following passage and solve the questions based on it.Taking note of the day-long heavy queue in front of the Tarangabad Transport Department office everyday for obtaining transport permits, the City Administration comes out with a ‘Single Office-Five Windows’ system for facilitating the process. For simplicity, the windows are named as W1, W2, W3, W4 and W5 respectively. Office hours are from 8:00 AM to 5:30 PM, barring Saturday, when the office closes by 2.30 PM. To streamline the rush and reduce pressure on the employees, the working hours of the aforesaid windows are defined in the following manner:1. W1 is open between 9.30 AM and 2.30 PM on Monday and Wednesday, between 8.00 AM and 11.30 AM on Tuesday and Thursday and between 3.00 PM and 5.00 PM on Friday. 2. W2 is open between 8.30 AM and 11.30 AM on Wednesday and Thursday, between 8.00 AM and 10.00 AM on Friday, and between 12.30 PM and 2.30 PM on Monday and Saturday. 3. W3 is open between 10.00 AM and 12.30 PM on Wednesday and Saturday, between 10.00 AM and 12.00 Noon on Friday, and between 3.30 PM and 5.30 PM on Monday and Thursday. 4. W4 is open between 11.30 AM and 3.00 PM on Tuesday, between 12.30 PM and 3.00 PM on Thursday and Friday, between 8 AM and 10 AM on Saturday and Monday and between 3.30 PM to 5.30 PM on Wednesday. 5. W5 is open between 2.00 PM and 4.00 PM on Monday, 3.30 PM and 5.30 PM on Tuesday and Friday, between 8 AM and 10 AM on Wednesday and between 10.30 AM to 12.30 PM on Thursday.On which of the following days, maximum number of windows is simultaneously open at 9.45 AM?
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MCQ->Force between the molecules of the same substance is called __________ force.....

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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