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e.sci test 3


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Assume that during North America's Dust Bowl Era of the 1930s, 10 inches of top soil were either blown away or washed away through wind and water erosion. How long will it take to restore this top soil given the data I provided in this course?
5,000 years
by definition, top soil is what soil horizon?
"A" horizon
sandy loam soil consists of about ___% clay?
in Canada, massive losses of top soil in the 1930s were due primarily to:
wind erosion
Given the rates of soil formation and soil erosion in "agricultural soils.ppt", how long would it take for nature to replace the top soil lost during just the first year following a forest clear-cut?
42 years
wild crop varieties, which are foind all around the worl, are resistant to pests, disease, early frost and drought because:
their gene pool is rich and diverse
"landrace" crops are
traditional crop varieties
of the approx. 200 domesticated plant cultivars in world, only ___& make up principal crops which today contribute about 75% of plant-derived calories
the "rusts" which typically attack wheat plants caused by:
reasearch that Norman Borlaug and his plant scientist collabortors accomplished in Mexico, which started in 1943 and which led to greatly improved varieties of wheat, required ___ years of work
19 years
breakthrough for Borlaug in his effots to create high-yielding wheat varieties that were not subject to loding occured when he came accross a Japanese dwarf wheat variety
Norman Borlaug's research team also focused on maize production in Mexico. Many efforts were made to cross-breed maize varieties to produce high-yielding varieties of maize, but for the most part these efforts failed. Why?
Maize is cross-pollinating. Crop improvements achieved through cross-breeding were quickly lost in just one growing season.
Why didn't Borlaug and his colleagues simply adopt hybrid corn varieties already successfully growing in the American Midwest?
American hybrid corn would not produce high yields in Mexico for a variety of reasons including the different intensity of sunlight in Mexico versus the United States..
Green Revolution agriculture is synonymous with Chemical agriculture.
crop irrigation is always a necessary part of Green Revolution infrastructure
Green Revolution crop varieties are less susceptible to crop disease and pest attack
a herbicide is a pesticide
the pesticide DDT has been foiund to be relatively harmless to humans
In one study, DDT levels in zooplankton were 0.04 parts per million (ppm). But DDT levels in raptors such as eagles were much higher - 25 ppm. What would the bioconcentration factor be in this case?
which pesticide in a nerve toxin
which of the following best describes euthrophication
Nutrients from agricultural runoff and/or from sewage treatment plants concentrate in receiving waters triggering algal growth. The dieoff of algal blooms creates a demand for dissolved oxygen which causes finfish and shell fish to die.
Aquatic environments generally display dissolved oxygen levels between 5 and 12 parts per million (ppm or mg/L). If dissolved oxygen levels fall below 2 ppm, these waters are described as:
In the video featuring Dr. Vandana Shiva, it is argued that agricultural biodiversity in India is related to not only to ecosystem stability, but also to the country's economic and cultural stability. How does agricultural biodiversity contribute to the
by creating different livelihoods for the many people needed to manage the wide diversity of crops and livestock operations
the experience of many Canadian farmers growing genetically modified crops designedto minimize pesticide use
crop yield have fallen and presticide use has risen
modern methods of creating GM crops allow plants scintists to insert a gene of interest into a crop genome precisely within a DNA sequence
one out of every ___ people in the world today in a farmer
the Bayer Corp. decided in 2004 to not proceed with GM corn in the UK because
the UK would not assume financial liability for possible enviro. problems caused by GM corn
adding antibiotics to animal feeds used on factory farms is necessary because
confining large numbers of animals in cages and pens creates unsanitary condtion with leads to disease
about ____% of all antibiotics use in the US is on factory farms
one of the following types of agriculture infrastructure cannot be used in organic farming
chemical fertilizer
a recent agriculture innovation by Monsanto Chemical COmpany is the chemical herbicide Roundup which kills weeds by which will not harm conventional soybean plants
delta endotoxin is
a naturally occuring pesticide
Sir Robert Howard of the UK is remembered as a renowned agriculture scientist because
he learned ancient methods of organic farming from farmers in India and brought that knowledge back to Europe
to convert from conventional agriculture to organic farming a farmer must avoid using any chemical fertilizers or chemical pesticides for ___ years
people developing societies of the world eat, on average, ___ as much meat as people in industrial societies
In southern China, some agricultural officials are worried about encouraging factory farm operations because:
they fear that animal diseases may spread in this warmer part of China
Much of today's world-wide fish catch is ground up to make fish meal which is used as an animal feed expecially in factory farms.
The two leading cereal crops used worldwide primarily as animal feed in factory farms are: .
soybeans and corn
cattle raised on pasture land require just as much feed grain as cattle raised in factory farms

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