PTE Listening Practice Test 4

"Octopuses are remarkable not only for their intelligence but for one of the most sophisticated camouflage systems in the animal kingdom. Specialised skin cells called chromatophores allow an octopus to change its skin colour almost instantly, while other cells called papillae can alter the texture of its skin to mimic rocks, coral, or seaweed. Unlike most camouflaging animals, octopuses appear to be colour-blind, yet they can still match the colours of their surroundings with remarkable accuracy, a puzzle researchers have not fully solved. One leading theory suggests that photoreceptors distributed across the octopus's skin, not just in its eyes, may allow it to sense light and colour directly through its body. Beyond camouflage, octopuses have demonstrated problem-solving abilities in captivity, including opening jars to reach food, navigating mazes, and even using coconut shells as portable shelters. Their nervous system is also unusual: roughly two-thirds of an octopus's neurons are located in its arms rather than its central brain, allowing each arm to process information and react somewhat independently. This distributed intelligence has led some researchers to argue that octopuses represent a completely separate evolutionary experiment in intelligence, quite different from that of vertebrates such as humans, dolphins or crows."

অক্টোপাস রঙ পরিবর্তনকারী কোষ (chromatophores) ও গঠন পরিবর্তনকারী কোষ (papillae) দিয়ে ছদ্মবেশ ধারণ করে, যদিও তারা রঙ-অন্ধ। এদের বুদ্ধিমত্তা অস্বাভাবিক — স্নায়ুর দুই-তৃতীয়াংশ বাহুতে থাকে, যা স্বাধীনভাবে কাজ করতে পারে।

"Artificial light at night, now present across most of the world's inhabited land, has been shown to disrupt a wide range of nocturnal species. Migratory birds that navigate by moonlight and starlight can become disoriented by city lights, sometimes causing fatal collisions with illuminated buildings. Sea turtle hatchlings, which instinctively move toward the brightest horizon after emerging from their nests — normally the reflection of the moon on the ocean — are frequently drawn inland toward artificial lighting instead, away from the safety of the sea. Insects such as moths are also strongly affected, often exhausting themselves circling artificial lights rather than pursuing normal feeding and mating behaviour, a disruption some researchers link to broader declines in insect populations. Several cities have begun adopting 'dark sky' policies, dimming or shielding outdoor lighting during key migration periods to reduce these effects."

"Telemedicine, which allows patients to consult doctors remotely via video call, has expanded rapidly in rural regions where specialist care was previously difficult to access. Patients in remote areas no longer need to travel for hours, sometimes across poor roads, simply to receive a routine consultation or follow-up appointment, saving both time and travel expense. Rural clinics have also used telemedicine to connect local nurses with specialist physicians in real time during emergencies, allowing for faster and more informed treatment decisions before a patient can be transferred to a larger hospital. Some barriers remain, however, particularly unreliable internet connectivity in the most remote communities, which can interrupt consultations at critical moments. Governments in several countries are now investing in rural broadband infrastructure partly to support the continued expansion of telemedicine services."

"Exploring the deepest parts of the ocean, such as the Mariana Trench, presents engineering challenges far greater than those faced in space exploration. At depths of nearly eleven kilometres, water pressure exceeds one thousand atmospheres, capable of crushing an unprotected submarine hull instantly. Specialised deep-sea submersibles must be built with extremely thick titanium hulls and precisely shaped, usually spherical, chambers to distribute this pressure evenly. Communication is another major obstacle, since radio signals do not travel well through water, forcing engineers to rely on acoustic signals that transmit information far more slowly than radio waves used in space missions. As a result, only a handful of piloted missions have ever reached the deepest points of the ocean floor, compared with hundreds of crewed spaceflights."

"Contrary to popular belief, the Amazon rainforest is not primarily responsible for the planet's oxygen supply, since nearly all the oxygen it produces during the day is reabsorbed by its own respiring plants and microorganisms at night."