(PUC Minas - 2003)
TEXTO PARA A PRÓXIMA QUESTÃO:
TEXT 1
One of the most important events of the twentieth century was the discovery of DNA, which led to the development of genetic engineering. Genetic engineering stands out as a significant twentieth-century event because it may allow us to end disease, hunger and pollution.
Although genetic engineering, as we know it today, is a relatively new science, for thousands of years, breeders of plants and animals have used breeding methods to produce better combinations of genes. We owe the success of modern technologies to the discovery of the structure of DNA by biologists James Watson and Francis Crick in 1953. Because of their discovery, scientists developed techniques for altering genes or combinations of genes in an organism. By changing an organism's genes, scientists were able to give organisms and their descendants different traits.
It is clear that the discovery of DNA and the subsequent development of genetic engineering techniques have dramatically changed our view of life and our ability to influence human health and the environment. These techniques allow doctors to insert normal genes into the cells of a patient with a hereditary disease to treat the disorder. Disorders that people have suffered and died from for centuries, such as cancer and cystic fibrosis, may now be eliminated.
In addition, scientists have engineered special genes into corn, tomato and soybean plants to make them resistant to disease. Improving the quality of food plants may lead to an end in world hunger. Genetic engineering also has potential in controlling pollution. Researchers are developing genetically engineered microorganisms that break down garbage, toxic substances, and other wastes.
(BLASS, Laurie; PIKE-BAKY, Meredith. Tapestry - Writing 2. Boston: Heinle & Heinle Publishers, 2000, p. 200. Adapted).
The word "which" refers to the
Gabarito: significant discovery of DNA.