高普考/三四等/高員級◆英文題庫下載題庫

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       To a great extent, we owe our current high standard of living to biological advances in food production. Plant and animal breeders have developed organisms that provide better sources of food than the original varieties. Corn is a grass that produces its seeds on a cob. The original corn plant had very small ears that were perhaps only three or four centimeters long. Through selective breeding, varieties of corn with much larger ears and more seeds per cob plant have been adapted to produce other kinds of corn, such as sweet corn and popcorn.

        Animal breeders also have had much success. The pig, chicken, and cow of today are much different animals from those available even 100 years ago. Chickens lay more eggs, dairy cows give more milk, and beef cattle grow faster. All of these improvements raise our standard of living. One interesting example is the change in the kind of hogs that are raised. At one time, farmers wanted pigs that were fatty. The fat could be made into lard, soap, and various other products. As the demand for fat products of pigs declined, animal breeders developed pigs that gave a high yield of meat and relatively little fat. Today, plant and animal breeders can produce plants and animals almost to specifications.