IELTS Academic Reading Practice Test 12

A For more than two thousand years, lighthouses have stood as the most visible aid to maritime navigation, marking dangerous coastlines, harbour entrances, and isolated reefs. The earliest known major lighthouse is widely said to be the Pharos of Alexandria, built around 280 BCE on a small island just off the Egyptian coast. Rising to perhaps 100 metres in height — an extraordinary structure for its era — the Pharos used a wood-fuelled fire at its summit to guide ships into the busiest port of the ancient Mediterranean. The tower stood for more than 1,500 years before successive earthquakes finally demolished it in the fourteenth century. Its long survival is widely said to have set a kind of precedent for monumental coastal navigation aids that subsequent civilisations would imitate at smaller scale wherever maritime trade was important.

B Medieval and early modern lighthouses were modest stone towers with open-flame coal or wood beacons at the top. Visibility was limited by smoke, weather, and the rudimentary fuels of the era, and the structures were widely understood to be vulnerable to storms. The first lighthouse known to use a glazed lantern room — a glass-enclosed chamber that protected the flame from wind and rain — was the Eddystone Light off the southwest coast of England, first lit in 1698. The Eddystone underwent multiple reconstructions over subsequent centuries as successive structures were destroyed by storms or fires, with each generation incorporating engineering improvements. The Eddystone's history is, in many maritime historians' view, broadly a case study in the iterative refinement of coastal engineering, with each rebuilding incorporating lessons learnt from the failure of the structure before it.

C The greatest technical advance in lighthouse history is widely considered to be the Fresnel lens, developed by French physicist Augustin-Jean Fresnel and first installed in 1823 at the Cordouan lighthouse near Bordeaux. The lens uses concentric rings of precisely-shaped glass to concentrate light from a single source into a narrow horizontal beam, increasing the effective brightness many times over and dramatically reducing the energy required for a given range. Fresnel lenses were classified into orders — first-order being the largest and most powerful, suitable for major coastal lights, down to sixth-order for harbour entrance lights — and the system remained in production for more than a century. The technology has, in many writers' view, stood as a touchstone of nineteenth-century precision engineering.

D The labour of operating a lighthouse was once considerable. A traditional lighthouse keeper, often supported by family, was required to maintain the light at all hours of darkness, wind clockwork weights every few hours to rotate the lens, replenish oil reservoirs, clean lenses and prisms, paint structures, and maintain logbooks of weather and shipping. Many lighthouses were on rocks or islands typically inaccessible for weeks at a time. The hardship of the work fostered a distinctive culture: keepers and their families lived in tight-knit communities, often passing the profession through generations. Memoirs published by retired keepers in the twentieth century have described a routine that was monotonous in detail but psychologically demanding in its responsibility for the lives of distant strangers.

E Lighthouse technology has progressed through electric arc lamps, incandescent bulbs, and now efficient LED arrays, while clockwork mechanisms have largely been replaced by electric motors. Most dramatically, virtually all major lighthouses have been automated, with permanent staff withdrawn over the latter half of the twentieth century. The last permanently manned lighthouse in the United Kingdom — the North Foreland in Kent — was automated in 1998, and the United States Coast Guard's last permanently staffed lighthouse, Boston Light, retained a single keeper into the twenty-first century only as what many describe as a heritage gesture. The withdrawal of resident keepers has, in many writers' view, closed a chapter of working maritime life that had endured in essentially unchanged form for centuries.

F The function of lighthouses has also evolved considerably. GPS and other satellite navigation systems have largely supplanted visual aids for ocean navigation, although lighthouses are regarded as remaining useful for inshore navigation, particularly in poor visibility or for vessels without electronic equipment. Many historic lighthouses now serve as museums, holiday accommodations, or simply as preserved monuments. The Royal Society for the Protection of Birds and equivalent organisations have repurposed several former keepers' cottages as research stations and visitor facilities, finding new uses for these distinctive coastal sites. The repurposing of lighthouses reflects a wider pattern in which obsolete industrial infrastructure acquires heritage value once its original function has lapsed.

A Since the introduction of penicillin in the 1940s, antibiotics have, according to most medical historians, transformed medicine, allowing routine treatment of infections that once killed millions and enabling surgery, transplantation, and cancer chemotherapy that depend on suppressing opportunistic bacteria. This success now appears partial and, in the view of many researchers, temporary. Resistance among pathogenic bacteria has been rising across the world, driven by overuse in medicine and agriculture, and is said to threaten to return modern medicine to a position similar to the pre-antibiotic era for at least some infections. The reversibility of medical progress has, in many writers' view, emerged as one of the most disquieting themes of contemporary global health.

B The biological mechanism of resistance is widely described as straightforward and essentially inevitable. Any natural population of bacteria includes rare individuals carrying mutations that confer some protection against a given antibiotic. When an antibiotic is applied, sensitive individuals are killed while resistant ones survive and multiply, eventually dominating the population. Resistance can also be acquired horizontally through plasmids — small DNA elements that bacteria exchange with each other — which can carry resistance to multiple antibiotics simultaneously. The same plasmid can spread between distantly related bacterial species, creating multi-drug resistance with what researchers describe as extraordinary speed. The horizontal transfer of plasmids has been identified as the central reason that resistance can arise so rapidly across an apparently diverse range of pathogens.

C The factors driving the current crisis are, according to public-health analysts, well documented. Hospital settings, where the most vulnerable patients receive the largest antibiotic doses, are regarded as reservoirs of multi-resistant strains. Inappropriate prescribing of antibiotics for viral infections continues despite repeated guidance. Agricultural use is, in researchers' view, enormous: roughly 70 percent of global antibiotic consumption is for animals, often given at sub-therapeutic doses to promote growth, with widespread spillover into the environment through manure and water. The 2015 World Health Organization Global Action Plan called for substantial reductions in such use, but compliance has varied widely between countries.

D The drug-development pipeline has not kept pace with the spread of resistance. Between the 1950s and 1980s, the pharmaceutical industry introduced new antibiotic classes regularly. Since around 2000, however, the pipeline is widely considered to have been nearly empty. Several new antibiotics have been approved in the past decade, but they are mostly variations on existing classes rather than fundamentally novel mechanisms. The economic problem is regarded as acute: an antibiotic against a resistant pathogen would, by design, be used sparingly and only when other options had failed, generating little revenue to repay decades of development investment. The market structure produces a perverse incentive in which the most needed drugs are also the least profitable to develop.

E Several promising responses are being explored. Combination therapy — using multiple antibiotics simultaneously — can slow the evolution of resistance, although it does not eliminate it. Bacteriophages, viruses that prey on specific bacterial species, have been used clinically in some countries throughout the antibiotic era and are increasingly attracting research investment in others. Novel antibiotic classes derived from previously unculturable soil microbes, including teixobactin discovered in 2015, have entered preclinical development. Improved stewardship programmes in hospitals have, in several studies, measurably slowed the local spread of resistance. The combined evidence suggests that no single intervention will resolve the crisis, but that a portfolio of overlapping approaches could meaningfully delay it.

F Public-health analysts generally emphasise that resistance is a global problem that, in their view, cannot be addressed by any one country acting alone. Resistant bacteria reportedly spread across borders through travel, trade, and environmental flows. The economic case for international cooperation is widely described as strong: a 2014 review commissioned by the United Kingdom government estimated that, without action, antimicrobial resistance could cause 10 million additional deaths per year by 2050 and reduce global economic output by 100 trillion US dollars cumulatively. The figures have been contested, but the broad direction of the analysis is, according to many specialists, widely accepted within the medical community.

A For most of the twentieth century, the dominant view of the adult human brain held that its essential structure was fixed by early adulthood, with subsequent development largely limited to gradual decline. This conception, advanced influentially by the Spanish anatomist Santiago Ramón y Cajal in the early 1900s, gave way reluctantly to mounting evidence in the second half of the century that the brain in fact continues to reorganise itself, sometimes dramatically, throughout life. The capacity for such reorganisation is now widely called neuroplasticity, and understanding it has, according to many neuroscientists, transformed thinking about learning, recovery from injury, and the limits of what mature human brains can do. The conceptual shift has been described as one of the most consequential reorientations in modern neuroscience, with implications that extend from clinical rehabilitation to educational practice.

B The earliest convincing demonstrations of neuroplasticity came from studies of sensory remapping after injury or amputation. The neuroscientist Michael Merzenich, working at the University of California San Francisco in the 1980s, is credited with showing that the cortical map representing the hand of a monkey would reorganise within weeks following the loss of a finger: the cortical area previously dedicated to the missing finger was taken over by the representations of adjacent fingers. The reorganisation was, in researchers' view, not subtle but visible at standard resolution in functional brain imaging. The Merzenich findings established that adult cortical maps are dynamic rather than fixed, and that even relatively limited peripheral changes can produce substantial central reorganisation.

C Studies of human stroke recovery have, according to many clinicians, provided some of the most compelling evidence for clinical neuroplasticity. Patients who suffer damage to the motor cortex on one side of the brain may initially be paralysed on the opposite side of the body, but through targeted physical therapy can often recover substantial function over months to years. Modern rehabilitation techniques typically exploit neuroplasticity by forcing patients to use the affected limb intensively. Constraint-induced movement therapy, developed by neuroscientist Edward Taub, restrains the unaffected limb to compel use of the impaired one — a counterintuitive approach that has produced superior results to conventional therapy in multiple controlled trials.

D The brain's ability to learn new motor and cognitive skills throughout life is widely considered to provide the most familiar form of neuroplasticity. Studies of London taxi drivers, conducted by neuroscientist Eleanor Maguire and colleagues at University College London, found that the posterior hippocampus — a brain region involved in spatial memory — was significantly larger in qualified drivers than in age-matched controls, and grew steadily during the years of training required to learn the city's 25,000 streets. The change reverted after retirement, suggesting that the structural change reflected active use rather than initial selection. The taxi-driver finding has, in many writers' view, broadly become the canonical example of experience-dependent structural change in the adult human brain.

E Critical periods — windows of heightened plasticity during early development — remain important in understanding neural function. Children who lose vision in one eye before approximately age eight typically develop normal vision in the other eye, while loss of vision in the same eye in adulthood does not produce the same compensatory development. Similar critical periods are widely understood to exist for language acquisition, with children exposed to a first language only after about age twelve failing to achieve full native fluency. Recent research has begun to identify the molecular mechanisms — particularly the role of inhibitory interneurons and extracellular structures called perineuronal nets — that close critical periods, raising the prospect that pharmacological reopening might eventually be possible.

F Practical applications of neuroplasticity research generally extend beyond medicine. Educational research has been influenced by evidence that targeted practice can produce measurable changes in brain structure, supporting approaches that emphasise active engagement over passive instruction. Cognitive training programmes for healthy ageing have been heavily marketed, although controlled trials have shown that benefits transfer poorly from the trained task to other cognitive abilities. The advertising claims of commercial brain-training products are widely said to have substantially outrun the supporting evidence, prompting regulatory action against several companies in the United States. The gap between scientific findings and commercial messaging has been described by neuroscientists as a recurring problem whenever a genuine research advance acquires a popular following.