单选题
Biotecbnology in one form or another has flourished since
prehistoric times. When the first human beings realized that they could plant
their own crops and breed their own animals, they learned to use biotechnology.
The discovery that fruit juices fermented into wine, or that milk could be
converted into cheese or yogurt, or that beer could be made by fermenting
solutions of malt and hops began the study of biotechnology. When the first
bakers found that they could make a soft, spongy bread rather than a firm, thin
cracker, they were acting as fledgling biotechnologists. The first animal
breeders, realizing that different physical traits could be either magnified or
lost by mating appropriate pairs of animals, engaged in the manipulations of
biotechnology. What then is biotechnology? The term brings to
mind many different things. Some think of developing new types of animals.
Others dream of almost unlimited sources of human therapeutic drugs. Still
others envision the possibility of growing crops that are more nutritious and
naturally pest-resistant to feed a rapidly growing world population. This
question elicits almost as many first-thought responses as there are people to
whon the question can be posed. In its purest form, the term "biotechnology"
refers to the use of living organisms or their products to modify human health
and the human environment. Prehistoric biotechnologists did this as they used
yeast ceils to raise bread dough and to ferment alcoholic beverages, and
bacterial cells to make cheeses and yogurts and as they bred their strong,
productive animals to make even stronger and more productive offspring.
Throughout human history, we have learned a great deal about the different
organisms that our ancestors used so effectively. The marked increase in our
understanding of these organisms and their cell products gives us the ability to
control the many functions of various cells and organisms. Using the techniques
of gene splicing and recombinant DNA technology, we can now actually combine the
genetic elements of two or more living cells. Functioning lengths of DNA can be
taken from one organism and placed into the cells of another organism. As a
result, for example, we can cause bacterial cells to produce human molecules;
cows can produce more milk for the same amount of feed, and we can synthesize
therapeutic molecules that have never before existed.
单选题
Human beings began to use bioteehnology
A. when they could walk on their feet.
B. before they could plant their own crops.
C. after they realized that they could raise their own animals.
D. as soon as scientists began their studies on biotechnology.
A. increase the function of various cells and organisms.
B. change the DNA of human beings.
C. find new human molecules.
D. produce more milk by increasing the number of cows.
【正确答案】
B
【答案解析】推理判断题。第二段中曾提到：The marked increase...gives us the ability to control the many functions of various cells and organisms...故A错在将原文的control换成了increase；由该段倒数第三句：……通过采用基因分离、DNA重组技术……可知，DNA是可以重组的；所以B正确。而C、D两项的内容分别与第二段尾句中谈到的“用菌细胞培养人类分子”和“牛吃相同数量的饲料可以产出更多的奶”不一致。