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Essential Environment: The Science behind the Stories (3rd Edition)

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Chapter 10 Testing Your Comprehension 1 Food production has been increased by cultivating more acres, by fertilizing and irrigating crops to alleviate nutrient limitations, by breeding more productive crops, and by increasing inputs of pesticides and fossil-fuel-derived power. Borlaug introduced high-yield, sturdy, disease-resistant wheat varieties to developing nations. 2 Pesticide resistance arises by natural selection. Following pesticide application, resistant individuals survive and reproduce at higher rates, and so the population inherits greater resistance as time goes by. 3 Biocontrol is the practice of using one species to limit the population size of another. For example, parasitoid wasps lay eggs on leaf-eating caterpillars, and the wasp larvae eventually kill the caterpillar. Integrated pest management (IPM) combines biocontrol and chemical methods to control pests, with close monitoring of populations, habitat alteration, crop rotation, transgenic crops, alternative tillage methods, and mechanical pest removal. 4 Over 800 species of cultivated plants rely on insects for pollination, including species from almonds to yams. In many cases, different species of insects are required to pollinate different species of plants, and so it is important to maintain all of those insect species. 5 Recombinant DNA is DNA that has been patched together from the DNA of multiple organisms.
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