As a researcher, I'm especially intrigued by fungus-growing ants, a group of 248 species that cultivate fungi as their main source of food. They include 79 species of leafcutter ants, which grow their fungal gardens with freshly cut leaves they carry into their enormous underground nests. I've excavated hundreds of leafcutter ant nests from Texas to Argentina as part of the scientific effort to understand how these ants coevolved with their fungal crops. Much like human farmers, each species of fungus-growing ant is very particular about the type, of crops they cultivate. Most varieties descend from a type of fungus that the ancestors of fungusgrowing ants began growing some 55 million to 65 million years ago. Ant farmers face many of the same challenges human farmers do, including the threat of pests. A parasite called Escovopsis can devastate ant gardens, causing the ants to starve. Likewise in human agriculture, pest outbreaks have contributed to disasters like the Irish Potato Famine, the 1970 corn blight, and the current threat to bananas. Since the 1950s, human agriculture has become industrialized and relies on monoculture, or growing large amounts of the same variety of crop in a single place. Yet monoculture makes crops more vulnerable to pests because it is easier to destroy an entire field of genetically identical plants than a more diverse one. Industrial agriculture has looked to chemical pesticides as a partial solution, turning agricultural pest management into a billion-dollar industry. The trouble with this approach is that pests can evolve new ways to get around pesticides faster than researchers can develop more effective chemicals. It's an arms race-and the pests have the upper hand. Ants also grow their crops in monoculture and at a similar scale-after all, a leafcutter ant nest can be home to 5 million ants, all of which feed on the fungi in their underground gardens. They, too, use a pesticide to control Escovopsis and other pests. Yet, their approach to pesticide use differs from humans' in one important way. Ant pesticides are produced by bacteria they allow to grow in their nests, and in some cases even on their bodies. Keeping bacteria as a living culture allows the microbes to adapt in real time to evolutionary changes in the pests. In the arms race between pests and farmers, farming ants have discovered·that live bacteria can serve as pharmaceutical factories that can keep up with ever-changing pests. Whereas recent developments in agricultural pest management have focused on genetically engineering crop plants to produce their own pesticides, the lesson from 55 million years of ant agriculture is to leverage living microorganisms to make useful products. Researchers are currently experimenting with applying live bacteria to crop plants to determine if they are effective at producing pesticides that can evolve in real time along with pests. Adapted from: https://theconversation.com/ants-with-their-wise-farming-practices-and-efficient-nauigation-techniques-could-lnspire-so/utions-for-somehuman-probl~ms-188939 8. What is the author's main purpose in writing the text? A. To discuss the benefits of natural pesticides as shown by ants. B. To report research on how ant-farmers can tackle down pests. C. To suggest an idea for agricultural researchers to pay more attention to ants D. To persuade readers to be more aware of the benefits of ants in their gardens E. To inform readers about the lesson on farming that humans can take from ants

Whether it's the melodic sound of an Eric Clapton solo or the growl of a heavy metal band, the electric guitar has influenced popular music and culture more than any other instrument. Rock's greatest musicians have always been closely identified with their guitars. But instruments being designed for tomorrow's pop stars may look and sound rather different from today's familiar electric and acoustic guitars. Since the time when the electric guitar was invented, there have been incredible changes to the technical design of the instrument. From what was once a rounded wooden box with a hole in the front, the guitar has evolved into the smooth solid body of the rock guitarist's 'axe'. The most modern guitars are really computercontrolled synthesizers. Adolph Rickebacker's Electro String Company produced the world's first electric guitar. It was made of wood and played on the user's lap. The first real breakthrough in design came in 1950 when Leo Fender, a Californian radio repairman, made the first solid-bodied electric guitar, the Fender Telecaster. Soon after the inventor Les Paul made the famous Gibson Les Paul. Fender launched its stylish Stratocaster two years later. The guitars became standard instruments against which newer guitar designs are measured. All sorts of dift:erent materials have been used to make guitars. Acoustic guitars are made from wood, which gives a soft tone. Wood is also a popular material in electric guitar manufacture, but more modern materials such as glass and carbon fiber are also used. There have also been guitars with metal bodies and necks though these were never popular with players, who claim metal feels cold in the hand. Plastics, on the other hand, have been more used in guitar bodies. A company that makes parts for the aerospace industry has begun to use a kind of fiberglass that was originally used in helicopter blades to make the bodies for its electric-acoustic instruments. As long as scientists and musicians work together harmoniously, the electric guitar will continue to benefit from technological innovations. But for all the efforts of the guitar companies' design engineers, production managers and quality controller, it's the musicians who finally make the instruments sing- and not necessarily in the way the guitar maker intended. From the text we may conclude that ... (A) wood remains the best material for making guitars (B) guitar materials control the type of music the musicians play (C) technology has played a significant role in the design and development of guitars (D) today's designs are not very much different from those of the past (E) the use of fiberglass in aeroplanes was inspired by guitar makers

18

0.0

Jawaban terverifikasi

Everyone likes to group things. Language students group word as verbs, nouns and so on; collections of words are classified as phrases, or clauses, or sentences, and these again are reclassified according to their function. In the same way, botanistsw classify plants as algae, or fungi, or gymnosperms, etc. Zoologysts classify animals as vertrebrates and investibrates. The vetrebrates can be further classified as mammals, reptiler, birds, fish, etc. Classification enables us to keep hold of more information and, if it is based on the right data, enables us to understand better the ideas we are studying. Chemists are no exception. The chemical classification of materials, if it is based on a good system, should enable us to understand better the many substances which exist in our word. What is to be the basis of our classification? Perhaps the most obvious one is appearance. Materials could be classified as solid, liquid or gas with some mixed types as, for example, mud being solid/liquid material and steam a liquid/gas material. Appearance could enable us to subdivide our main classification groups a little further; the solid may be green, or black, powdery or crystalline; the liquid may be colored, oily, thick, or free flowing; the gas may be colored. However, we soon realize that many probably quite different materials have the same appearance. Both air and the deadly carbon-monoxide gas, are colorless, odorless gases, but we would not like to group them as the same thing. Many different liquids are colorless, water-like materials. Paragraph 2 exemplifies the idea about classification that ... . A. chemicals may be solid, liquid, and gaseous. B. Appearance is not a useful basis in chemistry. C. The use of colors is better than that of appearance. D. Both colors and appearance should be considered E. Colors should be included for identifying appearance.

13

0.0

Jawaban terverifikasi

The bailout of the Chrysler Corporation by the federal government in 1979 was widely hailed as a success. Four years later Chrysler was profitable again, and proponents of the aimed that it had saved Chrysler from bankruptcy without costing the taxpayers one penny. But a closer examination of the facts of the case leads to a more complicated picture. In 1979 Chrysler was on the verge of bankruptcy. Thousands of workers had been laid off, creditors were unpaid and the senior management appealed to the administration of Jimmy Carter to provide more than 1 billion in tax rebates. The administration's proposal, however, was not for direct tax relief but rather for federal loan guarantees, which administration officials were initially estimating at a value of $750 million but which ultimately totaled more than $1.2 billion. When in 983 Chrysler was profitable again, supporters of the ballout claimed that the taxpayers had saved Crysler from bankruptcy without having spent a dime, since the federal government had not had to pay for any defaulted loans. Chrysler is supposed to pay the government the difference between the guaranteed rate the loans carry and the rate they would have carried had they been issued without the government guarantee. This is, however, not entirely the case. In the early 1980s Chrysler was allowed, under the terms of the bailout, to issue federally guaranteed bonds at a rate of 10.35 %. The Ford Motor Company, by contrast, was in better shape than Chrysler at the time, but was forced to issue bonds with a rate of %. It would seem then that Chrysler should have been paying the government a guarantee of at least 4%; in reality, however, Chrysler was only paying the government a guarantee of 1%. Further, he loss of jobs from cuts at Chrysler would have resulted in a reduction of payroll paxes to the federal government. 8. The author of the passage most likely considers the Chrysler bailout to be .... A. a model for future government interventions B. a warning to those who would support planned economies C. an example of an unsuccessful government bailout D. more costly than its supporters suggest E. a political decision that was unfair to the Ford Motor Company

1

0.0

Jawaban terverifikasi

The word gambut (peat) is taken from the name of a village, Desa Gambut (now Garnbut sub-district), which is located about 10 km east of Banjarmasin, South Kalimantan. It is at this place that for the first time, rice has been successfully cultivated in peat soiled rice fields. In the soil taxonomy system, peat soils are grouped into a separate soil order called hisiosols, which means that the land is predominantly composed of organic soil materials in the form of remains of plant tissues. The nature and the characteristics of peat soils can be determined based on their physical and chemical properties. Gambut has dark brown to blackish colors. Although its basic materials are gray, brown or reddish, after decomposition, the dark humid compounds will appear. Furthermore, based on the weight of the contents, peat soil or gambut, which has undergone further decomposition, has a content weight ranging from 0.2 to 0 3 g cm2. Due to the low content weight, peat has a large capacity-as water storage about 2-4 times its dry weight. In fact, moss peat that has not decomposed can store up to 12 or 15 even 20 times more water than its own weight. In addition, peat soil has a large absorption area, which is up to 4 times greater than montmorillonite clay. Next, peat soil has acidic reaction properties. Decomposition of organic matters will produce organic acids that accumulate in the bodv of the soil hence increasing the acidity of the peat soil. Generally, peat soil shows real resistance to changes in pH when compared to mineral soils. As a result, peat soil requires more limestone to increase the pH at the same level of the value of mineral soil. Thus, peat soil requires a higher dose of fertilizers than mineral soil. Furthermore, based on the nutrients contained in it, peal soil is a type of nutrient-poor soil. High levels of N and organic matters in peat soils are also accompanied by a high N nitrification process so that the activity of heterotrophic organisms is not well stimulated and the organisms active in the nitrification process can carry out (heir activities. Therefore, the levels of P (phosphorus) and K (potassium) of peat soils are generally lower than that of the mineral soils. Also, the plants cultivated on the peat soil are very responsive to the fertilization using P and K. (adapted fiom hilps://freelearningji.wordpress.com} The phrase * large capacity as water storage* in paragraph 2 can be replaced by ... A. Power to withstand heavy water currents B. Capacity to keep water flowing stable C. High quality and quantity of water D. Potential to make large water storage E. Ability to deposit a large amount of water

3

0.0

Jawaban terverifikasi

bagaimana cara kita supaya bisa menggunakan bahasa Inggris dengan waktu yg cepat??

10

5.0

Lihat jawaban (2)