Trunk of tree increases in grith due to cell division in which tissue? ?->(Show Answer!)

1. Trunk of tree increases in grith due to cell division in which tissue?

Answer: Meristematic tissue

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MCQ-> Read the passage carefully and answer the questions given below it. Certain words/phrases have been given in bold to help you locate them while answering some of the questions. Long time ago, in a forest, there lived a young antelope. He was fond of the fruits of a particular tree. In a village bordering the forest, there lived a hunter who captured and killed antelopes for various reasons. He used to set traps for animals under fruitbearing trees. When the animal came to eat the fruit, it would be caught in the trap. He would then take it away and kill it for its meat. One day, while visiting the forest in search of game, the hunter happened to see the antelope under its favourite tree, eating fruit. He was delighted. ‘What a big, plump antelope!’ he thought. ‘I must catch him. I will get a lot of money from selling his meat.’ Thereafter, for many days, the hunter kept track of the antelope’s movements. He realised that the antelope was remarkably vigilant and fleet footed animal that it would be virtually impossible for him to track him down. However, he had a weakness for that particular tree. The crafty concluded that he could use this weakness to capture him. Early one morning, the hunter entered the forest with some logs of wood. He climbed the tree and put up a machan (platform used by hunters) on one of its branches by tying the logs together. Having set his trap at the foot of the tree, he then took up position on the machan and waited for the antelope. He strewed a lot of iy ,ovef mrui bts eo rn2thoeig6round beneath the 11.004.3, tree to conceal the trap and lure the antelope. Soon, the antelope came strolling along. He was very hungry and was eagerly looking forward to his usual breakfast of delicious ripe fruits. On the treetop, the hunter, having sighted him, sat with bated breath, willing him to come closer and step into his trap. However, the antelope was no fool. As he neared the tree he stopped short. The number of fruits lying under the tree seemed considerably more than usual. Surely, something was amiss, decided the antelope. He paused just out of reach of the tree and carefully began examining the ground. Now, he saw what distinctly looked like a human footprint. Without going closer, he looked suspiciously at the tree. The hunter was well hidden in its thick foliage, nevertheless the antelope, on close scrutiny, was now sure that his suspicions had not been unfounded. He could see a corner of the machan peeping out of the leaves. Meanwhile the hunter was getting desperate. Suddenly, he had a brainwave. Let me try throwing some fruit at him,’ he thought. So the hunter plucked some choice fruits and hurled them in the direction of the antelope. Alas, instead of luring him closer, it only confirmed his fears! Raising his voice, he spoke in the direction of the tree —”Listen, my dear tree, until now you have always dropped your fruits on the earth. Today, you have started throwing them at me! This is the most unlikely action of yours and I’m not sure I like the change! Since you have changed your habits, I too will change mine. I will get my fruits from a different tree from now onone that still acts like a tree!’ The hunter realised that the antelope had outsmarted him with his cleverness. Parting the leaves to reveal himself, he I grabbed his javelin and flung it wildly at the antelope. But the clever antelope was well prepared for any such action on his part. Giving a saucy chuckle, he leapt nimbly out of the harm’s way.As mentioned in the story, which of the following can be said about the hunter ?
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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->What will be the output of the program? class Tree { } class Pine extends Tree { } class Oak extends Tree { } public class Forest1 { public static void main (String [] args) { Tree tree = new Pine(); if( tree instanceof Pine ) System.out.println ("Pine"); else if( tree instanceof Tree ) System.out.println ("Tree"); else if( tree instanceof Oak ) System.out.println ( "Oak" ); else System.out.println ("Oops "); } }...

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 below it. Certain words/phrases have been printed in bold to help you locate them while answering some of the questions. Once upon a time there was a King of Benaras who was very rich. He had many servants and a beautiful palace with wonderful gardens; he had chariots and a stable full of horses. But his most prized possession was a magnificent elephant called Mahaghiri. She was as tall as two men, and her skin was of the colour of thunder clouds. She had large flapping ears and small, bright eyes and she was very clever. Mahaghiri lived in her own special elephant house and had her own keeper, Rajinder. The King would often visit Mahaghiri to take her some special tit-bit to eat and check that Rajinder was looking after her properly. But Rajinder needed no reminding, for he also loved the elephant dearly, and trusted her completely. Every morning, he would take her down to the river for her bath. Then he would bring her freshly cut grass, leaves and the finest fruits he could find in the market for her breakfast. During the day, he would talk to her and, in the evening, he would play his flute to send her to sleep. One morning, Rajinder arrived as usual with fruit for Mahaghiri’s breakfast. Suddenly, before he knew what was happening, she picked him up with her trunk and threw him out of the stall, breaking his arm. She began to stamp on the ground and trumpet so loudly that it took several strong men all morning to bind her with ropes and chains, When the king heard about what had happened, he was very upset and sent for the doctor to help Rajinder. Then he called for his chief minister. “You must go and see Mahaghiri at once,” he said. “She used to be so kind and gentle, but this morning she threw her keeper out of her stall. I can’t understand it. She must be ill or in pain. Spare no expense in finding a cure.” So the chief minister went to see Mahaghiri. who was still bound firmly with ropes. First he looked at her eyes – they were as clear and bright as usual. Then he felt behind her ears – her temperature was normal. Next he listened to her heart that was fine too – and checked all over for cuts or sores. He could find nothing wrong with her. “Strange,” he thought. “I can find no explanation for her bad behaviour.”But then his eye was caught by something gleaming in the straw. It was a sharp, curved knife, like the ones used by robbers. Could there be a connection? That night, when everyone else had gone to bed, the chief minister returned to the elephant house. There, in the stall next to Mahaghiri’s, sat a band of robbers. “Tonight we’ll burgle the palace,” said the chief. “First, we’ll make a hole in the wall, then we’ll steal the treasure. “But what about the guards?” someone asked. “Don’t tell me you’re still afraid to kill! When will you learn to be a real robber?” From the shadows, the minister could see the elephant, her ears pinned back, listening to every hateful and violent word.”Just as I suspected,” thought the minister. Then he slipped out, bolted the door on the outside so the robbers could not escape, and went immediately to the king.”Your majesty,” he said, “I think I have found the cause of your elephant’s bad behaviour.” As soon as the king heard what the minister had to say, he sent for his guards and had the robbers arrested. “But what about the elephant? How can she be cured?’ he asked. “Well, your majesty, if Mahaghiri became dangerous through being.in the company of those wicked robbers, perhaps she could be cured by being in the company of good people.” “What a brilliant idea!” exclaimed the king. “Let us invite the friendliest, happiest and kindest people in the city to meet in the stall next to the elephant.” “Mahaghiri, the king’s most prized elephant, has been in bad company and has become violent and dangerous,” the minister told his friends. “Will you help her to become her old self again?””Of course,” they replied. “What do you want us to do?” “Just meet in the elephant house every day for the next week. Let her hear how kindly and thoughtfully you speak to each other, and how helpful you are.” So the minister’s friends met in the elephant house as planned. They talked together and enjoyed each other’s company. Sometimes they brought cakes and sweets to share; sometimes their children came and played happily in the straw. All the while, Mahaghiri watched and listened. Gradually, she became calmer. “I think it’s working,” said the minister. “Soon we’ll be able to remove the ropes.” Everyone felt a bit nervous when the day came for Mahaghiri to be untied. The king ordered everyone to wait outside as, very carefully, brave Rajinder began to undo the ropes around her ears and trunk. Next he removed the ropes holding her head. Finally, he loosened the thick chains holding her great feet. Everyone held their breath. What if she was still wild?Mahaghiri looked round shuffling her feet to stretch them. Then she slowly curled her trunk around her keeper’s waist and lifted him high into the air before placing him gently on her back. A great cheer went up. The king was delighted. “Let’s have a picnic to celebrate,” he announced. “Mahaghiri can come too.” What a great afternoon they all had! Mahaghiri bathed in the lake and gave the children rides. It seemed as though she had now become kinder, gentler and even more trustworthy than ever. But Rajinder never forgot what had happened and was always careful to set Mahaghiri a good example by being kind and friendly himself.As per the context of passage, what was the most prized possession of the king of Benaras ?
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