BEST IELTS General Reading Test 458

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BEST IELTS General Reading Test 458

IELTS GENERAL READING TEST 458 – PASSAGE – 3

IELTS GENERAL READING TEST – 458

READING PASSAGE – 3

Glue bones

A Torn flesh is usually easy to put back together with stitches, but when bone breaks, repairs are nowhere near as simple. Fractures that run in a straight line can often be placed back in their proper alignment and set in a cast for a period of time that allows the break to heal. Complex fractures, though, those that involve bones shattered into fragments, are more challenging.

Large fragments can, with the aid of metal screws and pins, be reattached and set in place for healing. Small fragments cannot be treated in the same way, as they are often too tiny to be connected with metal hardware. Medics have long sought a glue to do this work, and now Russell Stewart of the University of Utah may have found one in the secretions of a marine worm.

IELTS General Reading Test

B The sandcastle worm, as the beast is known, lives in a mineral shell. It does not, however, secrete this shell directly in the way that, for example, a mollusc would. Instead, it secretes a glue and uses this to stick bits of sand together to form its casing, in the way that a freshwater caddis fly larva does. The glue does not dissolve in water. Indeed, it is able to displace water and thus adhere to surfaces in aqueous solutions. It also solidifies soon after being secreted. It, or something like it, therefore sounds ideal for repairing bones.

C Dr Stewart and his team began by analysing sandcastle-worm glue to see how it works. What they found was a mixture of proteins, some positively charged and some negatively charged, and also a lot of calcium and magnesium ions. The combination produces a material that can, when circumstances are right, bind the protein molecules so tightly together that any water molecules between them are expelled.

IELTS General Reading Test

D The trigger for this to happen is a change in acidity. The gland in which the glue is generated is mildly acidic. In these circumstances the glue remains liquid. Seawater, however, is alkaline. This alkalinity causes the glue to set. It solidifies into a foam within 30 seconds and becomes a flexible, leathery substance over the course of several hours.

E Having understood how the sandcastle worm performs its trick, Dr Stewart was in a position to replicate it. Instead of proteins, he and his team used two synthetic polymers. These, however, had the same crucial chemical groups as their natural counterparts, and also similar electric charges.

IELTS General Reading Test

F The result, as the team reported to a recent meeting of the American Chemical Society, was a substance even better, from a medical point of view, than the natural glue. Not only did it solidify in response to changes in acidity, it also did so in response to changes in temperature, being liquid at room temperature and solid at body temperature.

G The resulting glue not only sticks bits of bone together in watery environments, but also does so with twice the strength of the glue used by the worm. In addition, although it is still early days, preliminary tests suggest it is both non-toxic and biodegradable. If further testing confirms this, it means that, as the broken bone heals, the glue will disappear naturally. Complex fractures will thus heal more easily.

IELTS General Reading Test

Questions 28 and 29

Write TRUE, FALSE or NOT GIVEN.

28. The topic of the text is broken bones.

29. Repairing smaller breakages with metal parts is harder than repairing larger ones.

Questions 30 – 34

Which paragraph contains the following statements

30. the man-made version of the sandcastle-worm glue is body-friendly

32. examples of how broken bones can be mended

33. how the sandcastle worm produces its shell

33. an explanation of how the sandcastle-worm glue adheres molecules together

34. how a man-made version of the sandcastle-worm glue was produced

IELTS General Reading Test

Questions 35 – 40

Complete the summary with ONE WORD from the text.

In order for the sandcastle worm to form its 35…………………. it produces a glue which it uses to stick together bits of sand. Because this glue is able to stick to surfaces even when they are in 36…………………. solutions, it is a useful substance in the process of bone repair. Dr Stewart, from the University of Utah, and his team have managed to produce a man-made version of the glue using artificial 37…………………. . If early 38…………………. prove correct, this man-made version seems to have added benefits over the natural version being 39…………………. as strong, and able to vanish from the repaired area 40…………………. .

IELTS General Reading Test

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