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BEST IELTS Academic Reading Test 498
IELTS ACADEMIC READING TEST 498 – PASSAGE – 2
IELTS ACADEMIC READING TEST – 498
READING PASSAGE – 2
The Pearl Nature’s rarest gem
A. Pearls are calcium deposits found inside the shells of molluscs. Most molluscs create chalky, brittle pearls, but the ones that are valuable are those from the small number of species whose pearls are covered in shiny mother-of-pearl or nacre. The majority of commercial pearls come from freshwater mussels and marine pearl oysters, though some other species (such as abalone) are also able to produce pearls covered in nacre. Most molluscs live in shell structures made of calcium carbonate that contain a matrix of proteins, fats and sugars.
The shell forms externally, against an organ called the mantle. The mantle is the wall of muscle which covers the fleshy organs of digestion, reproduction and movement and it secretes calcium carbonate through its skin to create the shell. The word mantle means cloak, like the cape that superheroes wear. The edges of the mantle often extend far away from the main part of the body, in the form of loose flaps.
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It secretes organic materials from its outer layer that dictate the shape, colour and pattern of the shell, and means there is an amazing diversity in types of mollusc shells. This organic mixture also controls the type of calcium carbonate that is deposited in the shell in multiple layers.
B. We are often told that natural pearls are formed by a grain of sand becoming lodged within the oyster. Many natural pearls do contain a foreign body in the centre, but the real reason that pearls are formed is that skin cells from the mantle are transported to another location within the shell. This usually happens after some kind of injury such as a break in the shell or an invasion by a parasite.
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These disturbed mantle cells grow a kind of sac that internally secretes the material that will create the pearl. Nacre pearls are essentially inside-out shells, with an inner core that resembles the rough outside of a shell and a surface that is like the mother-of-pearl layer that is usually found on the interior surface of a shell.
C. It seems that humans have always considered pearls beautiful. There is evidence of their use in decoration as far back as the Babylonian era, and early writing in most cultures makes mention of these precious gems, the only ones that are created by animals. The fourth century Chronicle of Mahavamsa refers to a thriving pearl industry in Sri Lanka 5,000 years before. It seems seawater pearls have been retrieved by divers since prehistoric times in the Red Sea, the Persian Gulf and the Gulf of Mannar in Sri Lanka, and the Chinese have been hunting for seawater pearls in the South China Sea since at least 200 CE.
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D. Fewer than one in every 10,000 wild oysters contains a pearl. Due to their rarity in nature, pearls have historically been a symbol of wealth and status, but in the 1920s a technique called culturing became available to mass-produce them and pearls became more affordable as the industry expanded. In gemology, the word ‘pearl’ only means natural pearls, and pearls that are created through culturing or other artificial techniques need to be clearly designated. Natural pearls can be differentiated from cultured pearls under X-ray, although this requires specialist knowledge and otherwise they are identical.
Cultured pearls are produced by injecting mantle cells – called the saibo – from a donor oyster, with a circular bead called a nucleus. The mantle cells grow around the bead to make a pearl. The saibo and nucleus technique seems to have been first developed in Australia by biologist William Saville-Kent but was taken by two of his workers to Japan. Kokichi Mikimoto, who had already been culturing half sphere or hemispherical pearls by inserting pearls with a piece of mother-of-pearl, acquired patents to the method in 1916. This technology enabled the mass production of cultured pearls.
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E. Pearls are found in freshwater and saltwater and they differ depending on what mollusc they have originated from. China increasingly commercially produces most of the world’s freshwater pearls and as they are abundant they are more affordable than the saltwater variety. White saltwater pearls come from Japan and other Pacific nations, which also cultivate pearls of multiple colours, ranging from black and grey to cream and gold, depending on the variety of oyster.
F. At the beginning of the twentieth century, the population of oyster beds in the ocean’s waters became severely depleted from overfishing and the population still has not completely recovered. Natural pearls are now only found in the seas of Bahrain and Australia. This rarity can be observed in the prices they reach at auction, with new finds and antique pearl jewellery selling for enormous amounts. Unlike the virtually indestructible diamond, the creation of natural pearls requires stable temperatures and clean seas, both of which have been disrupted by global warming and pollution. Virtually all pearls available today have been cultivated and farmed.
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Questions 14-19
Reading Passage 2 has six paragraphs, A-F.
Which paragraph contains the following information?
Write the correct letter, A-F.
14. a stolen idea
15. the places natural pearls can be found now
16. a part of the mollusc that is named after an item of clothing
17. the pearls that cost the least
18. what the mantle does to make a pearl
19. why pearls are such unique gems
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Questions 20-21
Choose TWO letters, A-E.
Which TWO points are mentioned in the text as showing growth?
A. the variety of mollusc shell forms
B. the number of pearls found in wild oysters
C. the sale of pearls in the 1920s
D. the price of cultured pearls
E. Chinese production of freshwater pearls
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Questions 22-23
Choose TWO letters, A-E.
Which TWO differences between cultured and natural pearls are mentioned in the text?
A. their shape
B. the type of oysters they come from
C. their value
D. their availability
E. their size
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Questions 24-26
Choose NO MORE THAN ONE WORD from the passage for each answer.
24. Pearls usually occur naturally when the shell has been damaged and a part of the …………….. has broken away.
25. Pearls are cultured by implanting …………….. and a nucleus into an oyster shell.
26. They are so rare now, when natural pearls come up at …………….. they are sold for huge sums of money.
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ANSWERS
14. D
15. F
16. A
17. E
18. B
19. D
20. C
21. E
22. C
23. D
24. MANTLE
25. SAIBO
26. AUCTION
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