[简答题] Biotechnology is the name that has been given to a very wide range of agricultural, industrial and medical technologies that make use of living (47)______ (e.g., plants or animals) or parts of living organisms to provide new products and services. Biotechnology’’s (48)______ lie in the ancient crafts of brewing(酿造), baking and the production of fermented(发酵) foods such as yoghurt and cheese. It was not until 1859 that the cause of both desirable and (49)______ changes in food was identified. Louis Pasteur provided a scientific understanding of these natural processes, which helped to improve the (50)______ of traditional fermentations and ensure the safe (51)______ of food and drink. Pasteur thought that living organisms were always needed to bring about the changes which occur during fermentation. Towards the end of the last century, however, it was realized that non-living extracts from cells could also cause changes that are normally associated with the activities of w