IELTS Secrets

READING PASSAGE 1

You should spend about 20 minutes on Questions 1–13, which are based on Reading Passage 1 on the following pages.

BIOLUMINESCENCE

Bioluminescence is light created by a living organism; it is a chemical reaction that takes place inside the plant or animal. In order for a plant or animal to be bioluminescent, two things must be present. Luciferin, the compound that makes the light, is produced inside the bodies of some animals and plants. Others get this from bacteria which live inside their bodies, and which produce light all the time. It is necessary for the organism to have some way of hiding this light when it is not wanted or needed, and this may be done by pulling the light-emitting organs inside the body, or by covering them with pieces of skin. Other bioluminescent creatures get luciferin from the food that they eat. When activated by an enzyme called luciferase, the resulting chemical reaction creates light, and this is what makes the plant or animal glow.

The colour of the light emitted by bioluminescent organisms varies greatly, depending on the habitat of the organism producing the light. Researchers have found that bioluminescence in the ocean is most commonly blue-green, because blue wavelengths from sunlight filtering down from the surface are the strongest. There are some exceptions; for example, the light produced by the dragonfish, known as 'dragonlight', is red. One use of this red glow is to create a means of private communication between male and female dragonfish that goes unnoticed by other fish. Land-based organisms that glow exhibit a greater variety of colours, and a small number glow in more than one colour. One example of this is the railroad worm, thus named because of its appearance after dark. It is, in fact, the larva of a beetle, not a worm, which glows red from its head with green bioluminescent spots down its body. Most often, however, land-based creatures use blue-green bioluminescence as in the ocean, but in the yellow spectrum. Fireflies are an excellent example of creatures which emit this kind of colour, with their flashing amber bottoms.

Having the ability to produce light serves multiple purposes. The angler fish is an excellent example of a deep-sea fish that uses bioluminescence to lure its prey; if smaller creatures come too close to the glowing fleshy growth which dangles just in front of the sharp-toothed predator's mouth, they are caught off-guard and eaten. Click beetles crowd on termite mounds after sunset, and anything that is lured by their glowing light will soon become sustenance. Having an inbuilt flashlight is an advantage when hunting for food in the dark. Dragonfish, for example, use their red light to see what is in their immediate environment and locate their next meal. Unlike the previous two examples, their red light is like a stealth light that allows them to act as if under an invisibility cloak; thus they can hunt, producing light to see by, but they remain undetected by their prey.

Defending yourself against predators can be the difference between life and death in the natural world. Invisibility is an asset; if an animal is not seen then it stands a better chance of not being eaten. Camouflage in shallow waters can be a challenge, since the sun's rays penetrate the water and anything swimming in the shallows creates a dark silhouette. Some species, such as hatchet fish, have developed bioluminescence to eliminate this tell-tale, using a technique known as 'counterillumination'. They project light from the underside of their form so that they appear to be sunlight travelling through the water, effectively disappearing from the gaze of predators looking up from below. Some fish can even adjust the amount of light they emit to perfectly balance with the rays penetrating the water.

Other defensive techniques are used underwater. For example, when under attack the sea cucumber attaches a sticky glowing packet of bioluminescence onto a passing fish so that the predator chases the fish while the sea cucumber gets away. Some bioluminescent squid flash brightly to startle any fish that come too close, buying the necessary time to swim to safety. The vampire squid lives in the dark depths of the ocean, so squirting black ink as other squid do would be ineffective. Instead, this particular species squirts out thick, glowing mucus to startle attackers and slow them down. Some insect larvae, commonly referred to as glow-worms, light up to tell other animals that they are toxic and to be avoided. Bioluminescence is also a useful way to attract attention from potential mates and to communicate. Fireflies flash to indicate that they are looking for a mate, while the less subtle male lantern shark entices female sharks by lighting up its reproductive organs. Fungi such as some toadstools or mushrooms use bioluminescence to disperse their spores, glowing to attract insects with the ultimate goal of broadcasting their colonies far and wide.

READING PASSAGE 2

You should spend about 20 minutes on Questions 14–27, which are based on Reading Passage 2 on the following pages.

ANCIENT EGYPTIANS – FOUNDING FATHERS OF PHARMACOLOGY?

The Greeks have been credited with being the earliest practitioners of modern Western medicine. Recent evidence has emerged, however, that suggests that ancient Egyptian studies of science-based medicine and pharmacology preceded the Greeks and, in particular, the Greek 'De Materia Medica', a written list of 600 drugs and their uses which has been dated to 50 CE, and which has historically been regarded as the first pharmacopoeia. The ancient Egyptians may have blamed disease on supernatural forces such as demonic attacks, gods or ghosts, and recited spells as cures, but their medical system also used scientific rigour in the development of drug-based remedies, and they recorded their pharmaceuticals at the time.

A plethora of Egyptian artefacts, including surgical instruments such as scalpels and pliers, prosthetic great toes on at least two mummies, and mummified remains revealing the successful treatment of serious injuries, all point to the substantial medical knowledge of these ancient people. Debate continues over the existence of a dental profession, as no evidence for this has yet been collected from mummified remains.

Twelve medical documents written on papyrus (ancient Egyptian paper made from the papyrus plant) have provided strong evidence that, as well as surgical knowledge, the Egyptians had a systematic approach to diagnosis and treatment.

Despite the fact that translators have been working on ancient Egyptian written records since the early nineteenth century, some meanings are still not exact, and pharmacological records are a particular challenge. Rosalie David, director of the KNH Centre for Biomedical Egyptology, explains that translators need to be able to cross-reference the meaning of a particular word in different contexts in order to exactly clarify its meaning. Some of the words in the medical papyrus texts appear only in lists and not in complete sentences, and often in one document only. Over the past 200 years, translators have been forced to make educated linguistic guesses at many words, followed by consultation of a current pharmacopeia to identify which commonly used pharmaceuticals of their own time had the same medicinal use as those stated in the papyrus. Until recently, however, about a third of the references to pharmaceutical constituents remained unclear.

Dr Jackie Campbell at the University of Manchester in Great Britain set out to conduct a meticulous five-year study of the papyrus texts to establish firmer identification of the constituent elements of Egyptian pharmacology, in order to determine the depth and efficacy of Egyptian pharmaceutical knowledge. Not being a linguist, Campbell employed scientific methods to validate the papyrus prescriptions.

As with artefacts and ruins, Egyptian flora is well-documented and verified and can be reconstructed in detail. Campbell began by cross-checking that the plants in the prescriptions actually grew or were traded in Egypt when the parchments were written; any that couldn't be verified at that time were ruled out. She then set out to study four vital parchments covering prescriptions dating from circa 1850 BCE to 1200 BCE, when precise measurement was introduced. These medical records all contained instructions which followed a systematic recording of the list of constituents and the means by which these were assembled and mixed for use, how they were dispensed, and the appropriate dosage. Comparing each prescription with current standards and scientific protocols, Campbell was able to verify or, in some cases, invalidate the medical efficacy of the remedy. Some constituents, such as aniseed, were included in the translations but would not have worked as prescribed, nor were they found in the region at that time.

Scientists are now able to clearly identify the constituents of over half of the original one thousand prescriptions and specify if each one would indeed have worked for its intended purpose. For a further 156 prescriptions, there were only minor constituents which could not be identified. Over sixty per cent of the prescriptions would have been of therapeutic value, at least to some extent, including those where not every constituent was verifiable. There are still over two hundred unaccounted for items; Campbell says it may never be possible to identify some of them.

After consulting a 1977 pharmacopoeia, Campbell found that sixty-two per cent of the verified constituents were still in use in the 70s; in fact, many are common today, albeit in synthetic form. The preparation of the ancient remedies also had parallels with techniques used by pharmacists today: boiling to concentrate a chemical, diluting when necessary, or grinding to release the active constituent from its surrounding plant matter. Seemingly without any knowledge of modern chemistry, Egyptians were able to use appropriate extraction techniques, such as soaking plants in either water or mild alcohol, depending on the solubility of the active compound. Some remedies required a two-phase extraction. Campbell found that over sixty per cent of the ancient remedies complied with the 1973 British Pharmaceutical Codex in all but one area; Egyptians did not know of the need for sterility protocols, although they did value cleanliness in their medical professionals.

The final test of Egyptian pharmacology was to discover the efficacy of the remedies for the problems they were prescribed for. Once again, Campbell was surprised by her findings. Despite the fact that Egyptians were primarily treating symptoms, lacking precise knowledge of the root cause of most medical ailments, she found that even down to the exact dosage, sixty-four per cent of those prescriptions had curative value comparable to contemporary prescriptions.

READING PASSAGE 3

You should spend about 20 minutes on Questions 28–40, which are based on Reading Passage 3 on the following pages.

HAPPINESS – IT'S ALL IN YOUR HEAD

Section A

The need to survive and procreate is at the root of adaptive behaviours for all life forms. However, humans may be distinct in their ability to respond consciously to a pleasurable stimulus, to recall this afterwards, and thus to anticipate another period of happiness and actively plan actions that may bring this about. This facility of abstract consciousness confers an evolutionary advantage on humankind, but at the price of an appreciation of our own potential unhappiness and inevitable mortality. Nonetheless, most humans are engaged in a constant struggle to achieve, and the urge to maximise and prolong happiness is one of our primary motivations for doing so.

Section B

To search for the specific areas of the brain responsible for happiness, more than a hundred students from the University of Wisconsin were recruited for an experiment. Each was sent 25 text messages a day, asking them to rank their positive and negative emotions throughout the day, both during ordinary activities and when playing a game which offered $15 rewards. In another part of the experiment, the research team used Magnetic Resonance Imaging scans to search for those parts of the brain that lit up in response to feelings of happiness. The team are wondering whether the information they collected will allow us to train our brains to extend and even multiply our happy moments. The experiment found that one small area of the brain appears to be the source of the prolongation of positive feelings. Repeated neuron firings in this area are associated with an extended duration of happy feelings. A team psychologist, Aaron Heller, believes that it is important to recognise that the duration of enjoyable emotions is as valuable as their strength. He is keen to learn more about the difference between someone who can richly enjoy a sunset and another who responds little to this event, and for whom happy emotions quickly diminish.

Section C

Following on from these initial findings, it appears that there are many parts of the brain that offer reward systems that respond to pleasurable stimuli, or that give us pleasure: three can be found deep within the brain and four others in the cerebral cortex (the outer layer of brain tissue). However, there are very few mechanisms that cause pleasure reactions in the form of a response we usually label as 'liking' – that is, a promotion and continuation of the pleasurable feeling. Of these, there are two or three tiny hotspots in the sub-cortex and some in the brainstem region. In experiments, these hotspots can be stimulated with tiny injections of drugs to produce a doubling or tripling of the sensation of liking. A further discovery is the motivational process we might describe as 'wanting', which responds to an attractive stimulus and desires the reward of repeated exposure to it. Drawing from these conclusions, we can perceive different areas of brain activity which correspond to 'pleasure', as a short-lived impact on the individual, to 'liking', as a more longterm response to that pleasure that can lead to improved mood, and to 'wanting', that operates as a motivational force to repeat pleasurable experiences.

Section D

The fact that these responses are different and occur in different parts of the brain may help to explain why addicts of all kinds may crave a reward without necessarily liking that reward. In extreme circumstances, an addict may want something that is fully recognised consciously as being undesirable – the dissociation occurs because of the lack of integration of the mental faculties and may be expected to lead to unhappiness. Similarly, the situation is bleak for someone whose pleasure regions of the brain do not function normally. The lack of a sensation of pleasure is an important symptom of mental illnesses, including depression. Damage to one area has proved to be a direct cause of 'anhedonia', or lack of pleasure. In animals with such damage, even the delight in sugary tastes can be lost so that they react as if the substance is bitter or otherwise foul-tasting. In humans, anecdotal evidence tells us that Parkinson's Disease patients who have been treated with tiny electrical probes to destroy a small group of cells in the brain may show a reduction in emotional expression, while stimulation of this area appears to help with depression. Changes in the structure of the brain here, caused by injury or disease, have been found to produce a complete absence of pleasurable sensations. This is not the full story about depression; however, in some cases there may be a kind of automatic appreciation of fundamental pleasures, but the more developed thought processes that normally arise, such as reflection on the enjoyment or anticipation of renewed pleasure, may no longer be available to some people.

Section E

This identification of brain regions related to enjoyment brings some confidence in understanding the mind's reception of sensory pleasures, but there are still significant gaps in our appreciation of the processes behind more sophisticated levels of enjoyment which might come from the arts, or from joyful play. Further, there are the broader pleasures that come from social interactions which are essential to humans: they run from the heightened sensory responses to touch from loved ones to the more abstract appreciation of reciprocity, social rewards and valued relationships.