填空题
Supermarket shoppers have never been more spoilt for choice.
But just when we thought traditional systems of selective farming had created
the most tempting array of foods money can buy, we are now being presented with
the prospect of genetically created strains of cabbages, onion, tomato, potato
and apple.
It may not tickle the fancy of food purists but it
fires the imagination of scientists, last week they discovered that the classic
Parisian mushroom contains just the properties that, when genetically mixed with
a wild strain of mushroom from the Sonora desert in California, could help it
grow en masse while at the same time providing it with the resilience of the
wild strain.
66. ______
"We have found a way of increasing
the success rate from one to 90 per cent."
This is just one of
the many products that, according to skeptics, are creating a generation of
"Frankenfoods". The first such food that may be consumed on a wide scale is a
tomato which bas been genetically manipulated so that it does not soften as it
ripens.
67. ______
Critics say that the new tomato—which cost
$25 million to research—is designed to stay on supermarket shelves for longer.
It has a ten-day life span.
Not surprisingly, every-hungry US is
leading the search for these forbidden fruit. By changing the genes of a
grapefruit, a grower from Texas has created a sweet, red, thin-skinned
grapefruit expected to sell at a premium over its California and Florida
competitors.
For chip fanatics who want to watch their
waist-lines, new high-starch, low-moisture potatoes that absorb less fat when
fried have been created, thanks to a gene from intestinal bacteria.
The scientists behind such new food argue that genetic engineering is
simply an extension of animal and plant breeding methods and that by broadening
the scope of the genetic changes that can be made, sources of food are
increased. Accordingly, they argue, this does not inherently lead to foods that
are less safe than those developed by conventional techniques. But if desirable
genes are swapped irrespective of species barriers, could things spiral out of
control? "Knowledge is not toxic," said Mark Cantley, head of the biotechnology
unit at the Organisation for Economic Co-operation and Development, "It has
given us a far greater understanding of how living systems work at a molecular
level and there is no reason for people to think that scientists and farmers
should use that knowledge to do risky things."
Clearly,
financial incentive lies behind the development of these bigger, more productive
foods. But we may have only ourselves to blame. In the early period of mass food
commerce, food varieties were developed by traditional methods of selective
breeding to suit the local palate. But as suppliers started to select and
preserve plant variants that had larger fruit, consumer expectations rose,
leading to the development of the desirable clones. Still, traditionalists and
gourmets in Europe are fighting their development.
68. ______
Even in the pre-packaged US, where the slow-softening tomato will soon be
reaching supermarkets, 1,500 American chefs have lent their support to the Pure
Food Campaign which calls for the international boycott of genetically
engineered foods until more is known about the consequences of the technology
and reliable controls have been introduced.
In the short term,
much of the technology remains untested and in the long term the consequences
for human biology are unknown. Questions have arisen over whether new proteins
in genetically modified food could cause allergies in some people.
69.
______
Then there are the vegetarians who may be consuming
animal non-vegetable proteins in what they think is a common tomato, or the
practicing Jew who unknowingly consumes a fruit that has been enhanced with a
pig's gene. As yet, producers are under no obligation to label "transgenetic"
products.
Environmentalists worry that new, genetically
engineered plants may damage natural environment. A genetically engineered
pest-resistant strain of plant that contacts with a native strain, for example,
could turn them into virulent weeds beyond chemical control.
Animal welfare groups worry about the quality of life of farm animals
manipulated so that they produce more meat, milk, and eggs but which may suffer
physical damage in the process.
70. ______
Many of these
fears spring from ignorance. And although it is hard to separate the paranoia
from the benefits, the fact remains that genetic engineering offers ways of
solving serious medical and agricultural problems.
A. Western
farmers have already bred cattle with mare muscle than a skeleton can
carry.
B. Supporters say the tomato, unsurprisingly called Flaw
Saw, will taste better because it will be able to mature on the branch
longer.
C. Consumer opposition means that there are genetically
manipulated foods on the German markets, and the Norwegian government has
recently put research into genetically engineered foods on hold.
D. For example, if a corn gene is introduced into a wheat gene for pest
resistance, will those who are allergic to corn then be allergic to
wheat?
E. "Mushrooms in the past were almost impossible to
cross," says Philippe Callac, one of the three scientists working on the
mushroom.
F. Genetic engineering will interfere with the balance
of nature.