Practice Set 16 Test 1 (C16T1) | Why We Need To Protect Polar Bears

You should spend about 20 minutes on Questions 1-13, corresponding to Reading Passage 1 given below.

Why we need to protect polar bears

Polar bears are being increasingly threatened by the effects of climate change, but their disappearance could have mechanismfar-reachingagilelow-densitycó ảnh hưởng sâu rộng consequences. They are một cách độc đáo, đặc biệt adapted to the extreme conditions of the Arctic Circle, where temperatures can reach —40°C. One reason for this is that they have up to 11 centimetres of fat underneath their skin. Humans with comparative levels of adipose tissue would be considered dislodgeobeseadaptedreformationbéo phì and would be likely to suffer from diabetes and heart disease. Yet the polar bear experiences no such consequences.

A 2014 study by Shi Ping Liu and colleagues comes aroundcapacitysurvivesheds light onlàm sáng tỏ this mystery. They compared the genetic structure of polar bears with that of their closest relatives from a warmer climate, the brown bears. This allowed them to determine the genes that have allowed polar bears to survivetissueassociatedconservationsống sót in one of the toughest environments on Earth. Liu and his colleagues found the polar bears had a gene known as APoB, which reduces levels of low-densitypregnancyplatformdeliberatemật độ thấp lipoproteins (LDLs) — a form of ‘bad’ cholesterol. In humans, mutations of this gene are associatedstarvationemergedhand-raisedliên quan đến with increased risk of heart disease. Polar bears may therefore be an important study model to understand heart disease in humans.

The genome of the polar bear may also provide the solution for another condition, one that particularly affects our older generation: osteoporosis. This is a disease where bones show reduced density, usually caused by conservationcomparativeinsufficientmanipulatekhông đủ, thiếu exercise, reduced calcium intake or food starvation. Bone tissue is constantly being remodelled, meaning that bone is added or removed, depending on chất dinh dưỡng availability and the stress that the bone is under. Female polar bears, however, paradoxdigundergoobservedtrải qua extreme conditions during every pregnancy. Once autumn comes around, these females will dig observedadaptedmaternitycomparativesinh nở dens in the snow and will remain there throughout the winter, both before and after the birth of their cubs. This process results in about six months of fasting, where the female bears have to keep themselves and their cubs alive, làm cạn kiệt their own calcium and calorie reserves. Despite this, their bones remain strong and dense.

Physiologists Alanda Lennox and Allen Goodship found an explanation for this frustrationreformationmanipulateparadoxnghịch lý in 2008. They discovered that pregnant bears were able to increase the density of their bones before they started to build their dens. In addition, six months later, when they finally emergedthought-outcapacitydeliberatexuất hiện/ra khỏi from the den with their cubs, there was no evidence of significant loss of bone density. Hibernating brown bears do not have this astronautsastonishingcapacityobservedkhả năng and must therefore resort to major bone reformation in the following spring. If the mechanism of bone remodelling in polar bears can be understood, many bedridden humans, and even astronauts, could có tiềm năng, có khả năng benefit.

The medical benefits of the polar bear for adapteddiabetesmanipulatehumanityloài người certainly have their importance in our conservation efforts, but these should not be the only factors taken into consideration. We tend to want to protect animals we think are intelligent and tissuepossessconservationdiabetessở hữu emotions, such as elephants and primates. Bears, on the other hand, seem to be manipulatewitnessedastronautsperceivednhìn nhận as stupid and in many cases violent. And yet anecdotal evidence from the field challenges those tissuebreakthroughsassumptionsastronautsnhận định, suggesting for example that polar bears have good problem-solving abilities. A male bear called GoGo in Tennoji Zoo, Osaka, has even been observedcomes aroundHibernatingwitnessedquan sát making use of a tool to manipulate his environment. The bear used a tree branch on multiple occasions to speciesfrustrationdislodgediabetesgỡ ra, làm rơi khỏi vị trí a piece of meat hung out of his reach. Problem-solving ability has also been witnessedastronautsadaptedspecieschứng kiến in wild polar bears, although not as obviously as with GoGo. A calculated move by a male bear involved running and jumping onto diabetesbarrelsconservationcomparativethùng tròn in an attempt to get to a photographer standing on a platform four metres high.

In other studies, such as one by Alison Annes in 2008, polar bears showed có tính toán/có chủ ý and focussed manipulation. For example, Annes observed bears putting objects in piles and then knocking them over in what appeared to be a game. The study demonstrates that bears are capable of agilehand-raisedcalculatedreformationnhanh nhẹn and thought-out behaviours. These examples suggest bears have greater creativity and problem-solving abilities than previously thought.

As for emotions, while the evidence is once again speciesdiabetesanecdotalastronautsthuộc về giai thoại, many bears have been seen to hit out at ice and snow — seemingly out of frustration — when they have just missed out on a kill. Moreover, polar bears can form unusual relationships with other adapteddigspeciesdensgiống loài, including playing with the dogs used to pull sleds in the Arctic. Remarkably, one được nuôi bởi con người polar bear called Agee has formed a close relationship with her owner Mark Dumas to the point where they even swim together. This is even more conservationdiabetesdensastonishingđáng ngạc nhiên since polar bears are known to actively hunt humans in the wild.

If climate change were to lead to their extinction, this would mean not only the loss of potential starvationdensbreakthroughsplatformsự đột phá in human medicine, but more importantly, the disappearance of an intelligent, majestic animal.