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  3. Some fish can swim in water below 0°C, low enough to freeze the blood of most creatures. However, some fish and insects can stay

Some fish can swim in water below 0°C, low enough to freeze the blood of most creatures. However, some fish and insects can stay

admin2015-01-31  50
问题     Some fish can swim in water below 0°C, low enough to freeze the blood of most creatures. However, some fish and insects can stay alive in the freezing water. One key to survival is a special protein in the fish’ s blood. The chemical is called the Antifreeze Protein, otherwise known as AFP and is commonly found in fish that live in cold waters.
    What does AFP do in these fish? First, we need to understand what happens when water freezes. When the temperature of the water drops below -1.0°C, tiny particles of ice start forming in the water. Each particle becomes larger and then sticks to other particles, forming blocks of ice. Fish take in this water and tiny particles of ice also form inside a fish’s body. However, the AFP in the blood of the fish surrounds these particles, preventing them from sticking together to form bigger pieces of ice.
    The application of AFP is promising. For example, AFP can be used to alter the taste and texture of ice-cream. It can also be used to store meat and vegetables more effectively by protecting food products from the formation of ice. Another application is in medical field, as AFP can help preserve organs for transplantation without freezing them. Scientists have known about AFP for more than 30 years, yet few of the technologies that use the AFP exist today. The process of getting the necessary amount of AFP from fish to make products was only recently discovered. Some companies in the United States and Canada have already made products using AFP, but they have yet to become popular. Although some researchers in Japan discovered that some local fish contained AFP and succeeded in creating AFP in the laboratory, more research is necessary. AFP tests will continue for these fish out of the water.
How does AFP work?
选项 A、It covers the small ice particles so that they remain separated from each other.
B、It turns ice back into water by breaking down ice piece by piece.
C、It allows the fish to find places in the ocean that have warmer temperatures.
D、It forms a protective layer around the fish’ s body, keeping it warmer.
答案A
解析 细节题。文章第二段最后指出the AFP in the blood of the fish surroundsthese particles，preventing them from sticking together to form bigger pieces of ice，选项A表述与原文接近，故选A。
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