PTE Listening Practice Test 10

"Mimicry, in which one species evolves to resemble another, has developed independently many times throughout the natural world as a survival strategy. In Batesian mimicry, a harmless species evolves to resemble a dangerous or unpalatable one, gaining protection from predators who have learned to avoid the model species; the harmless hoverfly's yellow-and-black stripes, closely resembling a stinging wasp, are a classic example. A related but distinct phenomenon, Müllerian mimicry, occurs when two or more genuinely dangerous or unpalatable species evolve to resemble one another, reinforcing a shared warning signal that benefits all species involved. Some species take mimicry further still, changing their behaviour as well as their appearance; certain octopuses can not only alter their skin colour and texture but also contort their bodies to imitate specific dangerous animals such as sea snakes. Researchers note that its effectiveness often depends on the relative rarity of the mimic compared to the dangerous model it imitates. Mimicry is not limited to visual appearance; some species mimic sounds, scents, or vibrations to deceive predators, prey, or potential mates. The repeated, independent evolution of mimicry across unrelated animal groups is often cited as a striking example of convergent evolution."

মিমিক্রি (একটি প্রজাতি অন্য প্রজাতির অনুকরণ করে) — Batesian (নিরীহ প্রজাতি বিপজ্জনক প্রজাতির অনুকরণ করে) ও Müllerian (একাধিক বিপজ্জনক প্রজাতি একে অপরের মতো দেখতে হয়)। কিছু প্রজাতি আচরণও অনুকরণ করে। এটি অভিসারী বিবর্তনের উদাহরণ।

"Researchers studying the relationship between social media use and political polarization have focused considerable attention on the role played by content recommendation algorithms. These algorithms are typically designed to maximise user engagement, and studies have found that emotionally charged or controversial content tends to generate significantly more engagement than neutral or balanced content, leading algorithms to recommend it more frequently. Over time, users who repeatedly engage with content reflecting a particular political viewpoint may be shown an increasingly narrow range of perspectives, a phenomenon sometimes called a filter bubble. However, some researchers caution against attributing polarization solely to algorithms, pointing out that users also actively choose which accounts to follow and which content to engage with, suggesting that individual behaviour and platform design likely interact to produce polarizing effects rather than either factor acting alone."

"Several major cities have experimented with restricting or banning private car access to their historic centres, and early evidence from these initiatives suggests a range of benefits. Air quality readings in car-free zones have shown measurable improvements, with reductions in both particulate pollution and traffic noise reported within months of implementation. Local businesses in some car-free districts have reported increased foot traffic, since pedestrians and cyclists tend to browse and stop more frequently than drivers passing through in vehicles. Public transport usage and cycling rates have also risen in cities that paired car restrictions with expanded bus, tram or bicycle infrastructure. Not every business has benefited equally, however, and some delivery-dependent shops have raised concerns about restricted vehicle access for loading and deliveries, prompting several cities to introduce dedicated delivery time windows to address the issue."

"Nuclear fusion, the process that powers the sun, has long been pursued as a potential source of abundant, low-carbon energy, since it produces no long-lived radioactive waste and uses fuel derived from readily available materials such as seawater. However, achieving controlled fusion on Earth requires heating hydrogen fuel to temperatures far exceeding those found at the sun's core, since Earth-based reactors cannot rely on the sun's immense gravitational pressure to sustain the reaction. Containing this extremely hot, charged plasma without letting it touch and damage the reactor walls has proven to be an enormous engineering challenge, typically requiring powerful magnetic fields generated by superconducting magnets. While recent experiments have achieved brief periods where a fusion reaction produced more energy than was used to trigger it, engineers still face significant hurdles in sustaining that net energy gain continuously and scaling the technology to a commercially viable power plant."

"The blue whale's heart, the largest of any animal on Earth, is roughly the size of a small car and can weigh as much as 180 kilograms."