单项选择题
| In recent years a new farming
revolution has begun, one that involves the (21) of life at a
fundamental level — the gene. The study of genetics has (22)
a new industry called biotechnology. As the name suggests, it
(23) biology and modem technology through such techniques as
genetic engineering. Some of the new biotech companies specialize (24)
agriculture and are working feverishly to duplicate seeds that give a
high yield, that (25) diseases, drought and frost, and that
reduce the need for (26) chemicals. (27)
such goals could be achieved, it would be most beneficial. But some have
raised concerns about genetically engineered crops. In nature, genetic diversity is created within certain space. A rose (28) be crossed with a different kind of rose, but a rose will never cross with a potato. Genetic engineering, (29) , usually involves taking genes from one species and inserting them into (30) in an attempt to transfer a desired characteristic. This could mean, (31) , selecting a gene which leads to the production of a chemical with anti-freeze quality from an arc- tic fish, and inserting (32) into a potato or strawberry to make it frost-resistant. In essence, then, biotechnology allows humans to (33) the genetic walls that separate species. Like the green revolution, (34) some call the gene revolution contributes to the problem of genetic uniformity — some say even more so that geneticists can employ techniques (35) as cloning and (36) culture, processes that produce perfectly (37) copies. Concerns about the erosion of biodiversity, therefore, (38) . Genetically altered plants, however, raise new issues, such as the effects that they may have (39) us and the environment. "We are flying blindly into a new era of agricultural biotechnology with high hopes, few constraints, and (40) idea of the potential outcomes," said science writer Jeremy Rifkin. |