Extremophiles are organisms that have been discovered on earth that survive in environments that were once thought not to be able to sustain life. These extreme environments include intense heat, highly acidic environments, extreme pressure and extreme cold. Different organisms have developed varying ways of adapting to these environments, but most scientists agree that it is unlikely that life on Earth originated under such extremes. Adapting to Extreme Heat
One type of extremophiles is called thermophiles. These organisms can survive at very high temperatures. In the 1960s, heat resistant bacteria were discovered in hot springs in Yellowstone National Park. This bacteria, thermusaquaticus thrives at temperatures of 70°C (160°F) but can survive temperatures of 50°C to 80°C (120°F to 175°F). A few years after these were discovered, other bacteria were found living under even more extreme conditions. Hydrothermal vents were discovered deep in the ocean and under such high pressure that the water boils at 340°C. It was a surprise to researchers to discover bacteria living and thriving in the vents at such extreme temperatures and pressures. Not only were there bacteria, but centimeters away where the water was cooler, was a complete ecosystem living off the bacteria. There were clams and tubeworms among other species. Adapting to Extreme Cold
Other extremophiles have developed ways to cope with cold. Deep ocean water is as a fairly constant temperature of 2°C, but because of its salt content, in colder areas, ocean water can reach temperatures as low at -12°C without freezing. Extremophiles known as psychrophiles are known to survive at these low temperatures. Different species have come up with different ways to survive these cold temperatures. Some have developed substances, such as glycerol or antifreeze proteins which lower the freezing point of water by several degrees. The main danger to organisms of freezing is the damage caused by ice crystals as water freezes and expands. Some species of frogs and turtles have proteins which actually facilitate the freezing of body liquids. If the animal’s body liquids begin to freeze, a chain reaction is started and all of the body’s liquids freeze rapidly. This prevents the formation of ice crystals large enough to do any damage. Many kinds of microorganisms can survive freezing and thawing, as long as the problem of ice crystals is avoided.
66.An:ecosystem:(paragraph2)can be best described as .
A.an interesting community that contains both living and non-living organisms
B.a large collective term for animals that eat bacteria
C.different types of plants and animals that compete for good
D.The place where temperatures and conditions are dangerous and extreme
67.The formation of large ice crystal is dangerous mostly because .
A.the animal can no longer breathe, and nutrient can’t be carried around the body
B.proteins cause the animal’s body liquids to freeze
C.the freezing and expansion of water could damage the animal’s organs
D.the temperature inside the animal becomes too cold to survive in
68.Which of the following statements is FALSE according to the passage?
A. Extremophiles live in environment other organism cannot survive in.
B. Extremophiles can survive in both acidic and high pressure environments.
C. The thermophile lives in extremely high temperatures.
D. Fresh water has a constant temperature of around 2℃
69.The pressure of this article is to .
A. Amuse and entertain scientists
B. Provide a personal opinion about an issue
C. Educate and inform readers
D. Predict the beginning of evolution |