Preface Microbiology is the study of microorganisms. Microbiology is undoubtedly the most popular subject of biological sciences. Micro- organisms are everywhere. They exist in a range of environments including in the air we breathe, in the food we eat and even within our own body. In fact we come in contact with countless numbers of micro-organisms every day. Although some microbes can cause disease, most are rather play a pivotal role in the processes that provide energy and make life possible. Some even prevent disease and others are used in attempts to cure disease. As microorganisms play diverse role in the world, microbiology continues to be an exciting and interesting discipline to study. In this book most relevant and current information’s in the form of objective type questions have been given in a concise, palatable and easily digestible fashion and it will be extremely useful for the students, teachers and researchers as well. Further it will continue to be an important subject to study with lot of recent developments and areas to be explored. With the implementation of new trimester/semester systems, the students have to face a number of quizzes, midterm and final examinations. This system evaluates the student’s learning capability and teacher’s teaching techniques on a regular basis. Mostly objective type and short notes are asked in the examinations. Again, in various competitive examinations namely IAS, IPS, IFS, CSIR, ICMR, ICAR, NET, JRF, SRF etc objective type questions are set to evaluate the depth of knowledge of a particular subject of the students. Further, a number of organization/institutions hold regular examination for admission in various degree programmes, award of merit scholarships and appointment on various jobs based on objective type questions. It is therefore hoped that the book will be extremely useful for teachers as well as students and personnel in the field of Microbiology and other disciplines of various institutions particularly associated with the diagnosis and epidemiological investigation of the diseases. Lastly, the authors will appreciate receiving comments on the quality of books and errors if any for further improvement of the book.