Part II Reading Comprehension Questions 21 to 25 are based on the following passage:
Across the United State, scientists are mounting what may become the most innovative agricultural research drive since the 1920's, then hybrid corn was developed. Surprisingly, the new genetic revolution is not taking place in America's fields. Instead, it is occurring in biology laboratories, for it involves the deliberate manipulation in test tubes of the genes of crop plants. This genetic engineering may prove the biggest boon to agriculture since plant breeding began.
The new concepts grew out of the bio-engineering of bacteria for viral diseases. Plant cells, however, are far more complex than bacteria, and it will probably take many years for today's encouraging laboratory results to have a major impact on the farm. In fact the payoff may not come until the next century.
But although bio-technologists are still in the earliest phases of this new field of science, they are already actively exploring ways to redesign plants so they will sunlight more efficiently, resist viruses and other pests, grow in hot or dry areas, in saline soils or in the presence of pesticides, and perhaps even make their own fertilizer out of nitrogen in the air. In addition, scientists have had early success in making wholly new plants that are unavailable by conventional plant breeding, a potato-tomato combination, for example.
The new technology holds the promise of virtually limitless horizons in food production. Only imagination sets the limits: frost-resistant wheat, tropical potatoes, saltwater rice, a plant producing a pea and a carrot - all may be with us one day.
21. What is the main topic of this passage? A) Bacteria bio-engineering. B) Genetic engineering. C) Agricultural technology. D) Virus bio-technology.
22. According to this passage, the new genetic revolution involves ____. A) experiments on plants in the fields B) developing strains of hybrid corn C) breeding plant genes in laboratories
23. Vaccines for viral diseases are often produced from ____. A) plant cells B) human hormones C) crop plants D) bacteria
24. From the passage we understand that conventional plant breeding produced ____. A) a potato-tomato hybrid B) new plant technology C) self- fertilizing plants D) less dramatic results than the new technology
25. What kind of plants will the new technology develop in the future? A) Cereals that will grow without sunlight. B) Root crops that will grow in hot countries. C) Rice with a salty flavor. D) Green and orange striped vegetables.
pea and a carrot - all may be with us one day.
