Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 26 to 30.

WHY WE NEED TO PROTECT POLAR BEARS? Polar bears are being increasingly threatened by the effects of climate change, but their disappearance could have (26) ______ consequences. They are uniquely adapted to the extreme conditions of the Arctic Circle, (27) _______ 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 obese and would be likely to suffer from diabetes and heart disease. (28) ______ the polar bear experiences no such consequences. A 2014 study by Shi Ping Liu and colleagues sheds light on this mystery. They compared the genetic structure of polar bears with (29) _____ of their closest relatives from a warmer climate, the brown bears. This allowed them to determine the genes that have allowed polar bears to survive 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-density lipoproteins (LDLs) - a form of 'bad' cholesterol. In humans, mutations of this gene are (30) _______ with increased risk of heart disease. Polar bears may therefore be an important study model to understand heart disease in humans. (Adapted from Cambridge English Academic IELTS 16 by Cambridge University Press)

 

Polar bears are being increasingly threatened by the effects of climate change, but their disappearance could have (26) ______ consequences.