IELTSwithJurabek

You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2.

Australia's camouflaged creatures

Many species of animal in Australia protect themselves by using camouflage - a way of 'hiding' by blending into the surroundings.

A Most species use camouflage to some extent. If they are convincing, they survive to pass their genes on to future generations. After generations of natural selection, animals can develop astonishingly complex camouflage techniques, manipulating shape, colour and movement. 'The principle of camouflage is to make it economically unviable for a predator to pursue a particular species of prey,' explains Professor Mark Elgar, of the University of Melbourne. 'Camouflage increases the search time and, as a consequence, the predator will simply target another species, either because it doesn't see the camouflaged individual or it just finds something more obvious to do.'

B The easiest way for an animal to disguise itself is to be invisible in its surroundings; to that end, stick and leaf insects have evolved complex camouflage to hide themselves from predators. Many have the texture of sticks or dry leaves, while others imitate living foliage, even the veins in a leaf. Some insects develop blemishes to match the spots caused by disease. A convincing appearance only works if its owner also acts the part, so during the day the creature using this type of camouflage keeps motionless, or sways like a dead leaf in the breeze. If disturbed, it falls to the ground and stays still. Entomologist Paul Zborowski, who has spent decades photographing inconspicuous creatures, rates the desert insects of Central Australia as the most convincingly disguised creatures he's seen. "It's an incredibly old habitat so the creatures have had a long time to adapt," Zborowski explains. Most of them behave like stones and don't move all day, feeding only at night.

C A tawny frogmouth sitting motionless on a stump also illustrates the importance of pairing a persuasive costume with behaviour. Professor Gisela Kaplan of the University of New England, in Australia, says the frogmouth's skill at camouflaging is learned behaviour. While adopting a pose may be a reflex of the bird, and can be observed in a hatchling's first week, the ability to choose a backdrop which matches its colouration does not develop for 4-6 months. When the chicks land they are usually highly conspicuous, and their parents try to signal to them to move to a safe location.

D Fixed camouflage is only good against a relatively unchanging environment, so some animals, such as the cuttlefish, have evolved an adaptable disguise. The cuttlefish can almost instantly change its colour, pattern and texture to match its surroundings, using specialised cells and muscles. On Queensland's reefs, scientists have been studying another ocean dweller that uses colour change, although not to blend into the surroundings. Dr Karen Cheney, from the University of Queensland, says the bluestiped fangblenny alters its colouration to mimic other species of fish, allowing it to travel with them and benefit from safety in numbers.

Its most impressive impersonation is of the black-with-neon-blue striped cleaner wrasse which eats the parasites on larger fish. Not only does the fangblenny benefit from the reduced predation that comes with the wrasse's beneficial relationships with other fish, but the disguise also lets it get closer to prey. It darts out from the safety of the wrasse's cleaning station to nip at unsuspecting fish passing by but doesn't attack those coming to be cleaned.

E The most famous form of mimicry, however, is for defence, not attack. Batesian mimicry refers to animals that gain protection from predators by imitating a dangerous organism, often using conspicuous colours. The nineteenth-century naturalist Henry Bates first suggested this camouflage technique after noticing that several Amazonian butterfly species looked the same. The technique was later called after him.

In Australian waters, the harmless harlequin snake eel sports the same black and white bandings as the highly toxic, yellow-lipped sea krait, ensuring no predator will attack. However, the success of Batesian mimicry depends on the ratio of mimics to originals. If a predator encounters too many that are edible, it will just assume none of the animals with those markings are dangerous, explains Martyn Robinson, an educational naturalist with the Australian Museum.

F An imitation of a more dangerous creature needn't be exact, just enough to make potential predators hesitate. The hawk moth caterpillar has markings resembling a snake's eyes on its abdomen. When confronted, the caterpillar pulls its head in and the 'eyes' flash open. Whether the potential predator thinks it has seen a snake, or is simply startled is unclear, but the outcome is that the caterpillar lives to see another day.

G In Queensland's tablelands, the chameleon gecko has another way of making predators hesitate. Its body is brown, but its tail is banded in black and white. Robinson explains that if attacked, the chameleon gecko will drop off its tail, which will wriggle around on the ground. Many lizards do this, but in the case of the chameleon gecko the tail bones actually rub against one another, so it squeaks. 'The predator is, of course, thoroughly absorbed by this black-and-white-striped, wriggling, squeaking thing on the ground, and the gecko can sneak away,' Robinson says. 'It's a one-time-only trick: the regrown tail is brown, the same as the gecko's body.' Such precise disguise and elaborate trickery illustrate the limitless possibilities of nature. But, as Robinson points out, only the most successful illusionists are here to tell the tale.

You should spend about 20 minutes on Questions 27-40, which are based on Reading Passage 3 below.

Why Good Food Tastes Good

As a professional food developer, Barbara Stuckey has to understand the how and why of taste in order to create new palate-pleasing food products. Her book, Taste What You're Missing, is the latest release in a recent spate of books on the multisensory perception of flavor. This new volume, though, is certainly targeted at a somewhat different audience from the others. It is part memoir, detailing the author's many years working in a major North American company focused on developing novel food and beverage products, and part self-help book, offering advice on how we could all improve our ability to taste.

The author lays out her position at the start of the book when she states that she longed to read a straightforward book written for a lay person that could teach how to taste food without first having to teach the science. Consistent with this objective, complex terms that might prove difficult for a lay audience to understand, such as orthonasal and retronasal olfaction, are cleverly simplified as 'nose-smelling' and 'mouth-smelling', respectively. Stuckey also strenuously objects to the label 'supertaster'. This is the term used to describe those individuals (approximately one quarter to one third of the population) who exhibit an increased sensitivity to certain tastes (especially bitter tastes) and textures of food.

The thorough research Stuckey conducted for this book also deserves commendation. The text includes numerous quotes from the interviews that she conducted with many of the best-known international figures from the world of flavor research. But Stuckey also does a great job of extending beyond what most academics are normally willing to say in print, but which may well turn out, ultimately, to be true. For example, she puts forward the provocative suggestion that there may be as many as 25 different basic tastes. While most researchers who are happy with the notion of a basic taste would agree with the inclusion of sweet, sour, salty, bitter, and nowadays probably also umami as basic tastes, it is interesting to realize that there are many other substances for which receptor sensitivity on the tongue has now been demonstrated.

Stuckey includes a number of case studies in her book, including some fascinating material on the preparation, and consumption, of food and drink by those who have lost one of their senses, such as vision or hearing. Also, when she realized that there was a lack of relevant research regarding the question whether those who are deaf suffer from reduced flavor perception, she collected relevant data herself.

umami: a taste sensation that is meaty or savoury

Stuckey's book is strongest in the numerous industry examples she provides from her work with a large food product development company in North America. Many of the cases she describes seem to hinge on trying to find the right balance of the basic tastes, and the right 'mouth-feel' for a particular food or beverage product. Indeed, one of the major themes that came out throughout the book was the importance of food consistency, and the temporal dynamics of changes in mouth-feel as we eat and drink. However, it is certainly an area of food science that is tricky to work on in an academic research setting. It is just much easier to change the color or aroma of a foodstuff, for example. However, on numerous occasions we see just how important the tactile attributes of various foods and beverages are to their success amongst consumers.

In Taste What You're Missing, one certainly gets a real sense of the kinds of problems that she and her colleagues are faced with on a daily basis in a commercial setting. Many of the cases that are described in the book involve the use of one taste to mask, or unmask, another; for example, adding salt to a grapefruit or tonic water can, paradoxically, make it taste sweeter. However, where I thought that Stuckey was on weaker ground was when it came to the neuroscience of tasting. For example, in the brief section on 'The expert eater brain' she confidently asserts that, 'Not only do tasting experts use more areas of the brain, they can enjoy the process of tasting better than novices.' While the second part of the claim may be true, the former statement fails to do justice to the complexity of much of the widely acknowledged published data available.

There were a number of other claims in the book that, intuitively at least, seem hard to swallow. For example, Stuckey contends that the human ear is so sensitive that people can tell the difference between hot and cold coffee simply by listening to the two being poured. Although not performed under strict laboratory conditions, Stuckey tested this on more than 500 people and 99% of them found it easy to distinguish between hot and cold water poured from the same tea kettle, from the same height, into the same teacup.

What is striking about the quotes on the cover of Stuckey's book praising the contents is that they all come from people working in the food industry; that is, from chefs and those placed in cookery schools. Ultimately, I suspect this volume will have a much more enthusiastic reception there, and, as per the subtitle to her book, amongst 'passionate eaters' everywhere, than necessarily among those academics who conduct research on flavor perception and may be more critical.