IELTSwithJurabek

PASSAGE 2

Read the text and answer questions 14-26

Coins - the first form of money

14A Few people pay much attention to coins; we take them for granted. Since the advent of paper currency and the abandonment of a monetary system based on intrinsic of actual value, they have been demoted to the status of change: what is left when you have paid for something with "paper" money. There is even a belief that they will one day be obsolete, as will paper or plastic notes, and money will at last have achieved the pure status of a mathematical formulation, a system of electronic credits and debits.

15B In the modern media environment, the sheer number of visual images is overwhelming, but it makes one stop to think that coins are among the most durable of our artefacts, and future archaeologists will scrutinise coins in order to learn about their distant ancestors. This is exactly the way ancient coins have informed us for over four millennia. There are thousands of different coins, each designed to carry meaning as well as value, tiny but rich sources of documentary evidence about events and cultural attitudes, frequently produced with exquisite craftsmanship.

16C Coins in Europe date from 2,500 to 2,700 years ago, and seem to have originated in the ancient kingdom of Lydia, in what is now Turkey. Before coins, trade was based on barter: the direct trade of commodities. Barter required the physical presence of both commodities that were being traded. Metal coins were far more portable, and not subject to the same spoilage on long sea journeys as a commodity like grain might be if it became wet. However, they could also be accumulated, and these hoards could be stolen. Coins were therefore a temptation to criminals. The Greeks, however, were the first to realise the full potential of the new invention. They were a trading people of seafarers. Their civilisation, which was composed of dozens of city-states, was highly decentralised. Despite the potential for theft, the Greeks realised that they could benefit enormously from a system that used coins, because it meant that they no longer had to carry goods with them to barter.

17D The value of coins was generally based on the intrinsic value of the metal they were made of. At first this was mostly silver, and this meant that the discovery of silver mines on Greek territory actually increased the quantity of money they could produce. Had the Greek mining been on a larger scale, it could have caused problems similar to those faced by the Spanish centuries later, when so much gold from the New World was brought into their economy that it resulted in serious inflation. One advantage of intrinsic value was that coins could be weighed to determine the amount of metal they contained, so that the only thing an issuing state had to guarantee was the purity of the metal to prevent accusations of fraud and cheating, which could cause fighting and unrest. This was quite difficult to do, especially with coins made of gold, until Archimedes realised that different metals have different weight-volume ratios, and that by measuring the amount of displacement when coins were immersed in water, it was possible to establish whether gold was alloyed with silver.

18E All ancient coins were made by hand using engraved metal moulds. Many hundreds of coins were made, and as a result the moulds often cracked and new ones had to be engraved. This explains the endless variety encountered in coins with the same designs because the moulds had to be remade repeatedly, by many different artisans. One of the distinctive features of coins, in fact, is that they are the work of anonymous craftsmen, and yet each coin is an intimate reflection of the character of its city of origin. It was the Greeks who realised that coins could have a double function, as a unit of value and as a symbol of the identity of the city that issued them. The Greek view of life was deeply motivated by a spirit of competition, and coins, which circulated around the trading world, were a way of advertising the qualities of each particular city-state.

19F Interestingly, Greek coins from the city of Athens, which was the home of the greatest sculptors of the classical period, seem to have been completely disconnected from the high sculptural tradition. The beautiful features of the city's patron, Athena (with her owl on the reverse of the coin), seem to have been repeated virtually unaltered for many years. Perhaps this was because the Athenian currency had grown increasingly to be the international standard and, like the US dollar today, a uniform design implied integrity.

20G One side of a coin was always occupied by the head of a divinity, so it was a relatively small step, at around 323 BC, for Greek coins to replace that head with the portrait of the reigning monarch, a tradition that has continued in monarchies to the present day. Republics may have either symbolic heads - going back to the older tradition of divinities - or the features of a distinguished past head of state. The Romans adopted the Greek practice of coin design and as a result, the features of many great Romans have survived and are known to modern generations, despite the fact that the art of portrait painting was completely lost for more than a millennium following the fall of the Roman Empire.

PASSAGE 3

Read the text and answer questions 27-40

Creating a Better Grapefruit

By blocking the right taste receptors, biotech researchers turn bitter into sweet.

A There is a reason why grapefruit juice is served in little glasses. Most people don't want to drink more than a few ounces at a time. This is because a natural chemical compound found in grapefruit, naringin, has a bitter taste. Some people like that bitterness in small doses and believe it enhances the general flavour, but others would rather avoid it altogether. So juice packagers often select grapefruit with low naringin content, even though the compound has antioxidant properties that some nutritionists contend may help prevent many serious diseases.

B It is possible, however, to get the goodness of grapefruit without the bitter taste. In a test conducted by a biotechnology company, sets of two miniature white paper cups, labelled 304 and 305, were placed before five people seated around a conference table. Each person drank from one cup and then the other, cleansing their palates between tastes with water and a cracker. Even the smallest sip of 304 had grapefruit's unmistakeable bite. But 305 was smoother; there was the sour taste of citrus but none of the bitterness of naringin. This juice had been treated with AMP, a compound that blocks the bitterness in foods without making them less nutritious.

C Taste research is a booming business these days, with scientists delving into all five basics: sweet, bitter, sour, salty, and umami (the savory taste of protein). However, bitterness is of special interest to the food industry because it is present in so many different types of food. There are thousands of bitter-tasting compounds in nature. They defend plants by warning animals away and protect animals by letting them know when a plant may be poisonous. But the system isn't foolproof. Grapefruit and bitter green vegetables like Brussels sprouts and kale are nutritious despite - and sometimes because of - their bitter-tasting components.

D "Humans are the only species that enjoys a bitter taste," says Charles Zuker, a neuroscientist at the University of California School of Medicine at San Diego. "Every other species is averse to bitter because it means bad news. But we have learned to enjoy it. We drink coffee, which is bitter, and quinine (in tonic water) too. We enjoy having that spice in our lives." Because bitterness can be pleasant in small quantities but repellent when intense, bitter blockers like AMP could make a whole range of foods, drinks and medicines more palatable.

E People have varying capacities for tasting bitterness and the differences appear to be genetic. About 75% of people are sensitive to the taste of some well-identified bitter compounds. Those who are sensitive seem to be less likely than others to eat bitter vegetables, according to Stephen Wooding, a geneticist at the University of Utah. Some people who have an unusually high number of taste buds, and are known as "supertasters", are especially sensitive to these compounds. Supertasters tend to shun all kinds of bitter-tasting things, including vegetables, coffee, and dark chocolate.

F The tongue is covered with taste buds. Under the microscope each one looks like an onion, consisting of 50 to 100 elongated cells running from the top of the taste buds to the bottom. At the top is a group of receptors that captures the taste molecules, known as tastants, in food and drink. The receptors function much like those for sight and smell. Once a bitter signal has been received, it is relayed via proteins known as G proteins. The G protein involved in the perception of bitterness, sweetness and umami was identified in the early 1990s by Robert Margolskee, at Mount Sinai School of Medicine in New York. The protein triggers a cascade of chemical reactions that lead to ion concentrations within the cell. Ultimately, this delivers a signal to the brain that registers as bitter.

G Once they understood the taste mechanism, scientists began to think of ways to interfere with it. They tried AMP, an organic compound found in breast milk and other substances, that is created as cells break down food. AMP has no bitterness of its own, but when put in foods, as Margolskee and his colleagues discovered, it attaches to bitter-taste receptors. As effective as it is, AMP may not be able to dampen every type of bitter taste because it probably doesn't attach to all 30 bitter-taste receptors.

H Some taste researchers believe that, in time, compounds like AMP will help make processed foods less unhealthy. Consider, for example, that a single cup of canned chicken noodle soup contains 850 milligrams of sodium chloride, or table salt - more than a third of the recommended daily allowance. The salt masks the bitterness created by the high temperatures used in the canning process, which cause sugars and amino acids to react. Part of the table salt could be replaced by another type of salt, potassium chloride, which tends to be scarce in some people's diets because of its bitter taste. But that bitter taste could be eliminated with a dose of AMP. Bitter blockers could also be used in place of sugary cherry and grape flavourings in children's cough syrups, and they could dampen the bitterness of drugs like antihistamines, antibiotics and other similar products.

I A number of foodmakers have already begun to experiment with AMP in their products, and other bitter blockers are being developed. In a few years, perhaps, after food companies have taken the bitterness from canned soup and improved the taste of medicines, they can set their sights on something more useful: a bitter blocker in a bottle that any of us can sprinkle on our Brussels sprouts or stir into our grapefruit juice.