What is biotechnology and how is it related to the problems of treating AIDS, preventing the development of cancerous tumors, and creating useful plants invulnerable to pests? The editors of "Question Mark" receive many letters with requests to answer these and many other questions related to the rapidly developing new scientific discipline - biotechnology, especially recently. The text of the book was translated from the original language using an artificial intelligence program. For the most part, the translation of the text is of very high quality, but in some cases, due to the imperfection of the technology, there may be incorrect phrase translations in the text, as well as single words and expressions may not be translated.