1. The numbers of nuclear divisions involved in a ciliate undergoing binary fission is





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MCQ->The numbers of nuclear divisions involved in a ciliate undergoing binary fission is....
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->An assertion and a reason are given below. Assertion: The phenomenon of nuclear fission generates great energy. Reason: The process in which a nucleus is broken into two parts is called nuclear fission. Choose the answer.....
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MCQ-> Please read the three reports (newspaper articles) on ranking of different players and products in smart phones industry and answer the questions that follow. Report 1: (Feb, 2013) Apple nabs crown as current top US mobile phone vendor Apple’s reign may not be long, as Samsung is poised to overtake Apple in April, 2013. For the first time since Apple entered the mobile phone market in 2007, it has been ranked the top mobile phone vendor in the US. For the latter quarter of 2012, sales of its iPhone accounted for 34 percent of all mobile phone sales in the US - including feature phones - according to the latest data from Strategy Analytics. While the iPhone has consistently been ranked the top smartphone sold in the US, market research firm NPD noted that feature phone sales have fallen off a cliff recently, to the point where 8 out of every 10 mobile phones sold in the US are now smartphones. That ratio is up considerably from the end of 2011, when smartphones had just cracked the 50 percent mark. Given this fact it’s no surprise that Apple, which only sells smartphones, has been able to reach the top of the overall mobile phone market domestically. For the fourth quarter of 2012, Apple ranked number one with 34 percent of the US mobile market, up from 25.6 percent year over year. Samsung grew similarly, up to 32.3 percent from 26.9 percent - but not enough to keep from slipping to second place. LG dropped to 9 percent from 13.7 percent, holding its third place spot. It should be noted that Samsung and LG both sell a variety of feature phones in addition to smartphones. Looking only at smartphones, the ranking is a little different according to NPD. Apple holds the top spot with 39 percent of the US smartphone market, while Samsung again sits at number two with 30 percent. Motorola manages to rank third with 7 percent, while HTC dropped to fourth with 6 percent. In the US smartphone market, LG is fifth with 6 percent. Note how the percentages aren’t all that different from overall mobile phone market share - for all intents and purposes, the smartphone market is the mobile phone market in the US going forward. Still, Samsung was the top mobile phone vendor overall for 2012, and Strategy Analytics expects Samsung to be back on top soon. “Samsung had been the number one mobile phone vendor in the US since 2008, and it will surely be keen to recapture that title in 2013 by launching improved new models such as the rumored Galaxy S4”. And while Apple is the top vendor overall among smartphones, its iOS platform is still second to the Android platform overall. Samsung is the largest vendor selling Android-based smartphones, but Motorola, HTC, LG, and others also sell Android devices, giving the platform a clear advantage over iOS both domestically and globally. Report 2: Reader’s Response (2013, Feb) I don’t actually believe the numbers for Samsung. Ever since the debacle in early 2011, when Lenovo called into question the numbers Samsung was touting for tablet shipments, stating that Samsung had only sold 20,000 of the 1.5 million tablets they shipped into the US the last quarter of 2010, Samsung (who had no response to Lenovo) has refused to supply quarterly sales numbers for smartphones or tablets. That’s an indication that their sales aren’t what analysts are saying. We can look to several things to help understand why. In the lawsuit between Apple and Samsung here last year, both were required to supply real sales numbers for devices under contention. The phones listed turned out to have sales between one third and one half of what had been guessed by IDC and others. Tablet sales were even worse. Of the 1.5 million tablets supposedly shipped to the US during that time, only 38,000 were sold. Then we have the usage numbers. Samsung tablets have only a 1.5% usage rate, where the iPad has over 90%. Not as much a difference with the phones but it’s still overwhelmingly in favor of iPhone. The problem is that with Apple’s sales, we have actual numbers to go by. The companies who estimate can calibrate what they do after those numbers come out. But with Samsung and many others, they can’t ever calibrate their methods, as there are no confirming numbers released from the firms. A few quarters ago, as a result, we saw iSupply estimate Samsung’s smartphone sales for the quarter at 32 million, with estimates from others all over the place up to 50 million. Each time some other company reported a higher number for that same quarter, the press dutifully used that higher number as THE ONE. But none of them was the one. Without accurate self-reporting of actual sales to the end users, none of these market share charts are worth a damn! Report 3: Contradictory survey (Feb, 2013) iPhone5 Ranks Fifth In U.S. Customer Satisfaction Survey inShare. The iPhone5 ranks fifth in customer satisfaction according to the results of a recent survey from OnDevice Research, a mobile device research group. In the poll, they asked 320,000 smartphone and tablet users from six different countries, how satisfied they were with their devices. According to 93,825 people from the US, Motorola Atrix HD is the most satisfying and Motorola’s Droid Razr took second spot. HTC Corp (TPE : 2498)’s Rezound 4G and Samsung Galaxy Note 2 took third and fourth spots, while Apple’s iPhone5 landed in fifth spot. It appears that Apple may be lagging in consumer interest. OnDevice Research, Sarah Quinn explained, “Although Apple created one of the most revolutionary devices of the past decade, other manufactures have caught up, with some Android powered devices now commanding higher levels of user satisfaction.” Despite the lower rankings, things aren’t looking too bad for Apple Inc. (NASDAQ:AAPL) elsewhere. In the United Kingdom, they ranked second place, right after HTC One X. Interesting enough, Apple did take top spot for overall satisfaction of mobile device, whereas Google Inc. (NASDAQ:GOOG) ranked second. Motorola Mobility Holdings Inc. (NYSE:NOK) took third, fourth, and fifth places respectively, while Sony Ericsson trailed behind at sixth place. The survey sampled mobile device users in the following countries: United States, United Kingdom, France, Germany, Japan, and Indonesia. Although OnDevice didn’t share the full list of devices mentioned in the survey, it does show some insight to what customers want. Unfortunately, there were still many questions regarding the survey that were left unanswered. Everyone wants to know why Google Inc. (NASDAQ:GOOG) was on the list when they are not an actual smartphone maker and why was Samsung Electronics Co., Ltd. (LON:BC94) on the bottom of the satisfaction list when the brand is leading elsewhere. Source: 92.825 US mobile users, July 2012 - January 2013 Fortunately, those questions were answered by OnDevice Research’s representative. He explained that the survey was conducted on mobile web where the survey software could detect the taker’s device and since user’s rate their satisfaction levels on a 1 to 10 scale, thanks to the Nexus device, Google was included.If you analyze the three reports above, which of the following statements would be the best inference?
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