PTE Academic Reading Practice Test 1
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Light in the Deep Ocean
ABioluminescence is the production and emission of light by living organisms. It occurs through a chemical reaction in which a light emitting molecule called luciferin reacts with oxygen, a process driven by an enzyme known as luciferase. Unlike the light produced by an ordinary bulb, this reaction generates almost no heat, and for that reason scientists often describe it as cold light. The phenomenon appears across a remarkable range of species, from fungi and bacteria to insects and fish.
BNowhere is bioluminescence more common than in the deep ocean. Below roughly 200 metres, sunlight fades almost completely, and researchers estimate that the majority of organisms living at these depths can generate their own light. In this dark environment, the ability to produce light offers clear survival advantages, and evolution has shaped it into many different forms.
CThe functions of this light are varied. Some fish use glowing lures to draw prey towards their mouths, while others release clouds of luminous material to confuse predators and escape. Certain squid match the faint light filtering from above so that their silhouettes disappear when seen from below, a technique known as counter illumination. Many species also use patterns of light to signal to potential mates.
DProducing light is not without cost. The chemical ingredients required are metabolically expensive, and a bright display may attract unwanted attention from larger hunters. As a result, most animals control their emissions carefully, releasing light only in short bursts or when a specific trigger occurs.
EHuman interest in bioluminescence has grown steadily. The genes responsible for the glow have been inserted into other organisms to act as markers in medical and biological research, allowing scientists to track processes inside living cells. What began as a curiosity of the natural world has become a valuable tool in the laboratory.
1What does the term cold light refer to in the passage?
2According to the passage, most organisms living below 200 metres in the ocean can
3Counter illumination allows certain squid to
4Bioluminescence is found only in ocean species.
5Producing light requires energy that the organism could otherwise use elsewhere.
6Scientists have counted the exact number of light producing species in the deep ocean.
7Genes linked to bioluminescence have been used in medical research.
8The chemical reaction behind bioluminescence is driven by an enzyme called .
9Some fish use glowing to draw prey towards their mouths.
10Most animals release light only in short or when a trigger occurs.
Farming in the Vertical City
AVertical farming is a method of growing crops in stacked layers, often inside buildings where the environment is fully controlled. Instead of relying on natural soil and sunlight, these farms use artificial lighting, carefully managed nutrients, and precise temperature control. The idea has attracted attention as cities expand and the amount of available farmland shrinks.
BOne of the main advantages of this approach is efficient use of space. Because crops are grown upwards rather than outwards, a vertical farm can produce far more food per square metre of ground than a traditional field. Many such farms are located within or close to cities, which shortens the distance food must travel before it reaches consumers and reduces the emissions linked to transport.
CWater use is another area of benefit. Vertical farms commonly rely on hydroponic systems, in which plants grow in nutrient rich water rather than soil. These systems recycle water continuously, and some operators claim they use as little as five per cent of the water required by conventional agriculture. This efficiency is especially valuable in regions where fresh water is scarce.
DThere are, however, significant obstacles. The artificial lighting needed to replace sunlight consumes large amounts of electricity, and this expense remains the biggest barrier to profitability. Unless the power comes from renewable sources, the environmental gains from reduced transport may be offset by the energy demand of the lights.
EDespite these challenges, the sector continues to grow. Improvements in energy efficient lighting and falling costs for renewable power are gradually making vertical farms more viable. Supporters argue that the technology will never fully replace traditional farming, but that it can supply fresh leafy greens and herbs to urban populations reliably throughout the year.
11What is given as a main reason vertical farming has attracted attention?
12According to the passage, the biggest barrier to profitability is
13Locating vertical farms close to cities mainly helps to
14Vertical farms always grow their crops in soil.
15Hydroponic systems can use far less water than conventional agriculture.
16Supporters believe vertical farming will completely replace traditional farming.
17Government subsidies have made most vertical farms profitable.
18In vertical farming, crops are grown in stacked .
19Many vertical farms use systems in which plants grow in nutrient rich water.
20Improvements in energy efficient are making vertical farms more viable.
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