Reading: True / False / Not Given: IELTS Academic 9990 (IELTS Academic)

Bioluminescence, the production of light by living organisms through internal chemical reactions, occurs in a remarkable range of species, from fireflies and glow-worms to fungi and, most abundantly, marine organisms. It is estimated that more than three-quarters of deep-sea creatures collected from depths below 700 metres are capable of producing their own light, making bioluminescence one of the most common forms of communication in that lightless environment. The chemical process typically involves a light-emitting molecule called luciferin reacting with oxygen in the presence of an enzyme, luciferase; the reaction releases energy as a photon of light rather than as heat, which is why the light produced by living organisms is often described as "cold light."

Marine biologists have identified several distinct purposes for bioluminescence among ocean species. Some organisms, such as certain species of anglerfish, use a glowing lure to attract prey close enough to be captured. Others rely on a sudden burst of light as a defensive tactic: when startled, some squid release a cloud of luminous ink to disorient a predator and gain time to escape. A third function is intraspecies signalling, several species of lanternfish possess characteristic patterns of light-producing organs, or photophores, arranged along their bodies in configurations that appear to help individuals recognise members of their own species in the dark.

Despite decades of study, several aspects of bioluminescence remain poorly understood. Researchers have yet to determine, for instance, why some deep-sea species that never encounter sunlight retain vestigial eyes capable of detecting light at all, while other species in the same habitat have lost their eyes' image-forming capacity entirely and instead rely on simple light-sensitive patches. What is clear is that the ocean's midwater zone, far from being a dark and empty void, is illuminated by a constant, shifting traffic of biological signals invisible to any observer without specialised low-light equipment.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. More than three-quarters of deep-sea creatures collected from below 700 metres can produce their own light.
2. The chemical reaction responsible for bioluminescence releases most of its energy as heat.
3. Anglerfish use a glowing lure to draw prey within reach.
4. Squid release luminous ink mainly in order to hunt prey rather than to escape from predators.
5. Bioluminescence has been observed in freshwater fish species.
6. Patterns of photophores on lanternfish may help individuals identify others of the same species.
7. Scientists have identified more functions for bioluminescence in shallow-water species than in deep-sea species.
8. Researchers have fully explained why some deep-sea species retain light-detecting eyes while others have lost image-forming vision entirely.

The urban heat island effect describes the tendency of cities to register significantly higher air temperatures than the rural areas that surround them, a difference that can exceed seven degrees Celsius during still, clear nights in large metropolitan areas. Several interacting factors are responsible for this phenomenon. Dark, impervious surfaces such as asphalt roads and roofing materials absorb a much greater proportion of incoming solar radiation than vegetated or unpaved ground, and because these materials also have a high thermal mass, they release this stored heat slowly after sunset, keeping nearby air warmer well into the night. At the same time, the removal of trees and other vegetation during urban development eliminates a natural cooling process known as evapotranspiration, in which plants release water vapour that absorbs heat from the surrounding air as it evaporates.

The dense arrangement of tall buildings compounds these effects by altering airflow: narrow streets flanked by high walls trap warm air and reduce the wind speeds that would otherwise disperse it, while the vertical surfaces of buildings reflect additional solar radiation back and forth between structures rather than allowing it to escape upward. Waste heat released directly by vehicles, industrial processes and air conditioning units, though a comparatively minor contributor in most cities, adds a further, constant source of warming that has no rural equivalent.

City planners in a number of countries have begun testing methods intended to counter the effect, including the installation of reflective "cool roofs" that are coated with light-coloured materials to reduce solar absorption, and the expansion of urban tree canopy along streets and in newly designed public parks. Early results from several pilot schemes indicate that surface temperatures on treated rooftops can fall noticeably compared with untreated roofs nearby, though researchers caution that citywide temperature reductions depend on how widely such measures are adopted and are difficult to measure precisely across an entire urban area, since air temperature is also affected by unrelated factors such as regional weather patterns and background climate trends that vary from year to year.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Cities can be more than seven degrees Celsius warmer than surrounding rural areas on some nights.
2. Vegetated ground absorbs more solar radiation than dark, paved surfaces such as asphalt.
3. Evapotranspiration is a natural process that cools the air as plants release water vapour.
4. Narrow streets between tall buildings tend to increase wind speeds, helping disperse warm air.
5. Waste heat from vehicles and air conditioning is, in most cities, the single largest contributor to the urban heat island effect.
6. Cool roofs are coated with light-coloured materials to reflect more sunlight.
7. Cool roofs cost more to install than standard dark roofing materials.
8. The urban heat island effect was first documented in the twentieth century.

Maggot debridement therapy, sometimes referred to as biosurgery, uses the larvae of certain fly species (most commonly the green bottle fly, Lucilia sericata) to clean chronic wounds that have failed to heal through conventional treatment. Sterile larvae, bred under laboratory conditions to eliminate any risk of introducing infection, are applied directly to a wound and either left loose beneath a permeable dressing or contained within a small mesh bag secured over the affected area. Over the following two to four days, the larvae feed selectively on dead and infected tissue while leaving healthy tissue largely undisturbed, a targeted feeding behaviour that distinguishes the treatment from surgical debridement, in which a clinician manually removes damaged tissue with a scalpel and cannot always avoid also removing some healthy tissue in the process.

The therapy's revival in modern medicine followed a period of decline after the introduction of antibiotics in the mid-twentieth century, when maggot treatment was largely abandoned in favour of pharmaceutical alternatives that seemed to make an insect-based method unnecessary. Renewed clinical interest emerged from the 1990s onward, driven partly by rising concern about bacteria resistant to standard antibiotics and partly by a series of clinical trials suggesting that larvae not only remove dead tissue efficiently but may also secrete substances with antimicrobial properties and compounds that appear to stimulate the growth of new tissue at the wound site.

Despite this renewed interest, maggot debridement therapy remains a minority treatment in most healthcare systems. Surveys of clinicians frequently cite patient reluctance as the principal barrier to wider adoption; many patients report finding the idea of live larvae on their skin distressing, even after being shown evidence of the treatment's effectiveness, and some clinics have found that patients withdraw consent once the dressing is removed and the larvae become visible. Cost is a secondary consideration in some healthcare settings, since sterile larvae must be produced and shipped under controlled conditions with a short shelf life, though this expense is frequently offset by shorter overall treatment times and reduced need for surgical intervention compared with conventional wound care.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Lucilia sericata is the fly species most commonly used in maggot debridement therapy.
2. The larvae used in this therapy feed indiscriminately on both healthy and dead tissue.
3. Surgical debridement using a scalpel always avoids removing any healthy tissue.
4. Maggot therapy was continuously used throughout the twentieth century without any decline in popularity.
5. Some studies suggest that larvae secrete substances that may help fight microbes.
6. Patient reluctance is identified as the main barrier to wider adoption of maggot therapy in clinician surveys.
7. The specific antimicrobial compounds secreted by the larvae have been chemically identified and named in clinical trials.
8. The cost of producing sterile larvae has decreased significantly over the past decade.

In 2003, engineers surveying land for a proposed reservoir in a low-lying river valley uncovered a series of timber posts protruding from thick layers of waterlogged peat. Subsequent excavation revealed the remains of a settlement, since named Mossgill Fen, that had been built on a raised wooden platform above what was once a shallow lake, and radiocarbon dating of the timber placed its construction at approximately 2900 BCE, making it one of the oldest lake-side settlements identified in the region. Because the site had been continuously waterlogged for almost five thousand years, oxygen was largely excluded from the sediment, and this anaerobic environment preserved organic materials (wood, textile fibres, and even food remains) that would ordinarily have decomposed within a few centuries in drier soil.

Among the most significant finds at Mossgill Fen was a wooden causeway roughly four hundred metres long, constructed from split oak planks laid across a foundation of driven posts, which appears to have connected the settlement to firmer ground on the valley's northern edge. Excavators also recovered several woven baskets still containing carbonised grain, indicating that the inhabitants cultivated cereal crops on nearby dry land despite living on a platform surrounded by water. Analysis of animal bones recovered from refuse deposits beneath the platform showed a diet supplemented substantially by fish and waterfowl, a detail that distinguishes Mossgill Fen from contemporary inland settlements in the same period, which relied almost exclusively on livestock and cultivated grain.

The site's excavators have proposed that the settlement was abandoned rather than destroyed, since no evidence of fire damage or violent conflict has been found among the structural remains, and valuable items such as tools and ornaments were left behind in a manner more consistent with a planned departure than a hurried flight. A leading theory holds that a gradual rise in the surrounding lake's water level, evidenced by successive layers of platform repair and heightening found in the excavation, eventually made continued habitation impractical, though the excavation team has not yet been able to establish precisely how long the settlement's abandonment took to complete.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Mossgill Fen was discovered during a survey carried out for a proposed reservoir.
2. Radiocarbon dating placed the construction of the settlement at approximately 2900 BCE.
3. The waterlogged conditions at the site caused organic remains to decompose faster than they would have in typical dry soil.
4. The inhabitants of Mossgill Fen grew no cereal crops and depended entirely on fish for food.
5. The number of people who lived at Mossgill Fen at its peak has been precisely calculated by archaeologists.
6. The causeway discovered at the site was built from split oak planks laid over driven posts.
7. Dyes used to colour the textile fibres found at the site have been chemically identified.
8. Excavators found clear evidence that the settlement was destroyed by fire or violent conflict.

Fast radio bursts, first identified in 2007 through a re-analysis of archived radio telescope data, are intense pulses of radio emission that last only a few milliseconds yet release, in that brief interval, more energy than the Sun produces over an entire day. Despite their extraordinary power, fast radio bursts were initially treated with scepticism by parts of the astronomical community, partly because a handful of similar signals detected at the same observatory were later traced to microwave ovens operated by observatory staff during meal breaks, a mundane source of interference that took researchers several years to isolate and rule out as an explanation for the genuine astrophysical bursts.

The overwhelming majority of confirmed fast radio bursts are one-off events: a single pulse detected from a particular direction in the sky that has never repeated, despite repeated follow-up observations of the same location using more sensitive instruments. A smaller subset, however, has been shown to repeat, sometimes at semi-regular intervals spanning days or weeks, and this distinction has become central to current theories about the phenomenon's origin, since a source capable of repeating clearly cannot be destroyed by whatever process produces a single burst. Magnetars (neutron stars with extraordinarily powerful magnetic fields, trillions of times stronger than Earth's) are currently the leading candidate to explain at least the repeating bursts, following the detection in 2020 of a comparatively faint burst originating from a known magnetar within our own galaxy.

Locating the precise origin of a fast radio burst outside our galaxy remains technically demanding, since the signal must be captured simultaneously, or nearly so, by multiple widely separated radio telescopes in order to calculate its direction with sufficient precision, a technique that has nonetheless allowed astronomers to trace a growing number of bursts to specific host galaxies, several of which lie billions of light years away. Researchers now hope that, because the radio signal is subtly delayed and dispersed by its passage through intergalactic gas on the way to Earth, careful study of large samples of these bursts may eventually provide a new way to measure the quantity and distribution of ordinary matter dispersed throughout the space between galaxies. Matter that is difficult to detect directly because it is far too diffuse to observe through a telescope in visible light.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Fast radio bursts were first identified in 2007 by analysing archived radio telescope data.
2. A single fast radio burst releases more energy in a few milliseconds than the Sun produces in an entire year.
3. Some early candidate signals that resembled fast radio bursts were eventually traced to microwave ovens at the observatory.
4. The majority of confirmed fast radio bursts have been observed to repeat at regular intervals.
5. The total number of fast radio bursts detected worldwide to date is known precisely.
6. In 2020, a faint fast radio burst was traced to a magnetar located within our own galaxy.
7. All of the radio telescopes involved in detecting fast radio bursts are located in the southern hemisphere.
8. Locating the origin of a fast radio burst from outside our galaxy can be achieved using a single radio telescope acting alone.

Before the mid-nineteenth century, most towns and cities kept their own local time, calculated according to the moment the sun crossed the meridian directly overhead. A system known as solar time, or "local mean time." Because the sun reaches its highest point at slightly different moments as one travels east or west, a traveller moving even a few hundred kilometres could find that noon in one town occurred several minutes earlier or later than in the next. Such small discrepancies caused little difficulty when travel was slow, but the rapid expansion of railway networks in the 1840s and 1850s turned them into a serious practical problem: railway companies needed a single, predictable time by which to publish timetables and coordinate the movement of trains along shared track, since a scheduling error of even a few minutes could result in a collision.

In Britain, railway operators adopted a solution known as "railway time," a single standard set to the local time of the Greenwich observatory near London, and gradually persuaded towns along their routes to reset their public clocks to match it. By 1855, the vast majority of public clocks in Great Britain displayed Greenwich time rather than local solar time, although the practice was not made a legal requirement across the country until 1880.

A far more ambitious version of the same idea was later proposed by the Scottish-born Canadian engineer Sandford Fleming, who argued that the entire globe should be divided into twenty-four standard time zones, each one hour apart and each spanning roughly fifteen degrees of longitude. Fleming's proposal was debated at the International Meridian Conference, held in Washington, D.C. in 1884, at which delegates from more than twenty nations voted to adopt Greenwich, England as the location of the "prime meridian," the zero-degree reference line from which every other time zone would be measured.

Adoption by individual countries nonetheless proceeded unevenly. France, for political reasons, continued to calculate its official time relative to Paris rather than Greenwich for several more decades, even while its trains ran on a timetable that was, in practice, a fixed number of minutes behind the Greenwich standard, before eventually aligning its civil clocks with the international system entirely.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Before the mid-nineteenth century, most towns calculated their own local time based on the moment the sun reached its highest point in the sky.
2. By 1855, only a small minority of public clocks in Great Britain displayed Greenwich time.
3. Railway time was not made a legal requirement across Britain until 1880, even though it had already been widely adopted by then.
4. Railway time spread more quickly across Scotland than across England.
5. The idea of adopting a single standard time for British railways was first suggested by Sandford Fleming.
6. Sandford Fleming was born in Canada.
7. Sandford Fleming proposed dividing the world into twelve standard time zones.
8. Delegates at the International Meridian Conference voted to make Greenwich the location of the prime meridian.

Across most high-income countries, the proportion of people living alone has risen steadily for several decades, a shift demographers describe as one of the most significant changes to household structure since industrialisation. In many Western European nations, people living alone now make up close to forty per cent of all households, a figure that would have seemed extraordinary a century ago, when unmarried adults typically resided with parents, other relatives, or in shared lodgings out of economic necessity.

Several factors are usually cited to explain this trend. Rising life expectancy means that a growing number of elderly widows and widowers now spend years, sometimes decades, living independently after the death of a spouse, rather than moving in with adult children as was once customary. At the other end of the age range, young adults are marrying later, if at all, and increasingly value the autonomy of living alone during the years between leaving the family home and forming a long-term partnership. Greater financial independence among women, in particular, has removed one of the strongest historical incentives to marry primarily for economic security.

The consequences of this shift extend well beyond housing statistics. Property developers in many cities have responded by building a far higher proportion of one- and two-bedroom units than in previous decades, sometimes provoking criticism that family-sized housing has become scarce and unaffordable. Public health researchers have also raised concerns about chronic loneliness among certain groups of people who live alone, particularly elderly people with limited mobility and few nearby relatives, and several city governments have launched befriending schemes and community hubs aimed specifically at reducing social isolation.

Not every commentator views the trend negatively, however. Sociologists studying the phenomenon note that living alone is not the same as being lonely: many people who live alone maintain dense social networks and describe their domestic independence as a deliberate and satisfying choice rather than a symptom of social breakdown. Whether policymakers should treat the rise of solo living chiefly as a housing challenge, a public health concern, or simply a neutral reflection of changing personal preferences remains an open question.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. In some Western European countries, people living alone constitute close to forty per cent of all households.
2. A century ago, most unmarried adults maintained their own independent households.
3. Elderly widows and widowers today are more likely to move in with their adult children than to live alone.
4. The average age of first marriage is higher in Western Europe than in any other region of the world.
5. Greater financial independence among women has reduced one of the traditional economic reasons for marriage.
6. Property developers have been legally required to increase the number of one-bedroom homes they build.
7. Research described in the passage indicates that everyone who lives alone suffers from chronic loneliness.
8. Some city governments have introduced schemes specifically designed to reduce social isolation.

As freshwater supplies come under increasing strain from population growth, irrigated agriculture and prolonged drought, many coastal regions have turned to desalination, the removal of salt from seawater, as a way of securing a reliable water supply that does not depend on rainfall. Although several techniques exist, the method used to produce roughly two-thirds of the world's desalinated water today is reverse osmosis, a process that forces seawater at high pressure through a semi-permeable membrane whose microscopic pores allow water molecules to pass through while blocking the larger dissolved salt ions.

Before seawater reaches the membranes, it must first pass through a pre-treatment stage that removes larger particles, algae and suspended sediment, since these would otherwise clog the membrane and shorten its working life. The pre-treated water is then pressurised, typically to between fifty and eighty times normal atmospheric pressure, and pumped through banks of membrane modules. Because pressurising such large volumes of water demands a considerable amount of electricity, energy consumption has historically been the single largest ongoing cost associated with reverse-osmosis plants. More recently, the introduction of energy-recovery devices, which capture pressure from the concentrated leftover brine and use it to help pressurise incoming seawater, has cut the electricity required per litre of fresh water produced by roughly half since the 1990s.

The process leaves behind a concentrated by-product known as brine, a highly saline liquid that is typically discharged back into the sea near the plant's outflow. Marine biologists have raised concerns that, if not sufficiently diluted before release, brine can settle near the seabed and reduce oxygen levels in the surrounding water, potentially harming bottom-dwelling organisms close to the outflow. Some newer plants address this by mixing the brine with treated wastewater before release, or by dispersing it through diffusers designed to spread the discharge across a wider area of seabed.

Despite these environmental trade-offs, reverse-osmosis desalination has expanded rapidly since the early 2000s, and several arid coastal cities now rely on it for a substantial share of their municipal water supply, a dependence that was rare before large-scale membrane plants became commercially viable.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Reverse osmosis is used to produce roughly two-thirds of the world's desalinated water today.
2. In reverse osmosis, dissolved salt ions pass through the membrane while water molecules are blocked.
3. Seawater passes through a pre-treatment stage that removes particles and algae before reaching the membranes.
4. Reverse-osmosis plants are cheaper to build than plants using other desalination methods.
5. Energy-recovery devices work by capturing pressure from the leftover brine to help pressurise incoming seawater.
6. Energy-recovery devices have increased the electricity required per litre of fresh water produced since the 1990s.
7. Dispersing brine through diffusers is a cheaper method than mixing it with treated wastewater.

For much of the twentieth century, conventional wisdom in education held that the best way to consolidate new material was to reread it repeatedly, and generations of students were advised to highlight textbooks and revisit their notes as exam dates approached. Beginning in the 1970s, however, a growing body of experimental research in cognitive psychology began to challenge this assumption, revealing a phenomenon now widely known as the testing effect: attempting to recall information from memory, even in the absence of any feedback, embeds that information far more durably than simply re-reading the same material an equivalent number of times.

In a typical experiment demonstrating this effect, one group of students studies a passage and then rereads it, while a second group studies the passage once and is then tested on it, without being told whether their answers were correct. When both groups are tested again a week later, the group that engaged in retrieval consistently outperforms the group that merely reread the material, despite having spent no additional time reviewing the original text and despite the first test producing no corrective feedback.

Researchers have also documented a related principle called the spacing effect: information reviewed in several short sessions spread over days or weeks is retained substantially better than the same total amount of study time compressed into a single lengthy session immediately before an exam. Combining retrieval practice with spaced review (for example, using flashcards to quiz oneself at gradually lengthening intervals) is now regarded by many cognitive scientists as among the most reliably effective study techniques available, more so than either technique used alone.

Despite this substantial evidence, surveys of students consistently find that rereading and highlighting remain the most commonly used study strategies, while active retrieval and spaced review are used far less often. One explanation offered for this mismatch is that rereading a familiar passage generates a comforting but misleading sense of fluency, leading students to overestimate how well they have actually learned the material, whereas the effortful struggle of retrieval, though more productive, feels less pleasant and less indicative of progress while it is happening.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. The testing effect shows that recalling information from memory helps retention more than rereading the same material the same number of times.
2. In the experiment described, students who reread the passage performed better on the later test than students who were tested on it.
3. Students who took the initial test were told immediately whether their answers were correct.
4. The spacing effect shows that spreading study sessions across several days improves retention compared with one long session.
5. Cognitive scientists agree that spaced review alone is more effective than retrieval practice alone.
6. Surveys show that most students continue to use rereading and highlighting as their primary study methods despite evidence favouring other techniques.
7. According to the passage, rereading gives students an accurate sense of how well they have learned material.
8. The testing effect was first identified by researchers studying university students specifically.

Before the 1950s, loading and unloading a cargo ship was a slow, labour-intensive process. Goods arrived at the dockside individually packed in barrels, crates, and sacks of wildly varying shapes and sizes, and dockworkers known as longshoremen had to load each item into a ship's hold by hand, a process that could keep a vessel tied up in port for a week or more. Since ships earn revenue only while at sea carrying cargo, this idle time in port represented an enormous and largely unavoidable cost to shipping companies.

The solution came from an American trucking entrepreneur, Malcolm McLean, who reasoned that instead of unloading a truck's cargo piece by piece at the dock, the entire truck trailer, minus its wheels, could simply be lifted onto a ship as a single sealed unit. In 1956, McLean's converted tanker ship carried fifty-eight such metal containers from New Jersey to Texas, marking the first commercial container shipment. Within two decades, standardised steel shipping containers, built to a small number of internationally agreed sizes, had become the dominant method of moving manufactured goods around the world.

The economic consequences were far-reaching. Because containers could be loaded and unloaded by crane in a fraction of the time required for loose cargo, port turnaround times fell dramatically, and the cost of shipping a tonne of goods across an ocean dropped to a small fraction of its previous level. This collapse in transport costs made it economically viable for manufacturers to relocate factories to countries with lower labour costs while still shipping the finished goods cheaply to consumers thousands of miles away, a shift that many economic historians regard as one of the central enabling conditions of late twentieth-century globalisation.

Containerization also reshaped the geography of port cities themselves. Traditional docklands, once crowded with warehouses and dockworkers, were increasingly abandoned in favour of large automated terminals built on the outskirts of cities, where there was sufficient space for stacking containers and manoeuvring cranes. Many former dockside districts in cities such as London and New York were later redeveloped for housing and offices, since the jobs and infrastructure that had once defined them as working ports had moved elsewhere.

Do the following statements agree with the information given in the passage? Write TRUE, FALSE or NOT GIVEN.

1. Before the 1950s, ships typically spent a long time in port because cargo was loaded and unloaded by hand.
2. Malcolm McLean was a manufacturer of steel shipping containers before he began working in the shipping industry.
3. The first commercial container shipment carried fewer than one hundred containers.
4. Shipping containers are built in a wide variety of different sizes to suit individual shipping companies.
5. The fall in shipping costs made it economically practical for manufacturers to move production to countries with cheaper labour.
6. Container shipping reduced the number of shipping accidents at sea.
7. Former dockside areas in some cities have been redeveloped for housing and office use.
8. Malcolm McLean's company remained the largest shipping container operator in the world throughout the twentieth century.