Microbiology COMPLETED EXAM 2026 13pages

1. What is the difference between sterilization and disinfection? - Sterilization is the process of destroying all forms of microbial life, including spores, on an object or surface. Disinfection is the process of reducing the number of pathogenic microorganisms to a level that is not harmful to health. 2. What are the three main shapes of bacteria and how are they named? - The three main shapes of bacteria are cocci (spherical), bacilli (rod-shaped), and spirilla (spiral-shaped). They are named based on their arrangement, such as staphylococci (clusters of cocci), streptobacilli (chains of bacilli), and spirochetes (flexible spirilla). 3. What is the difference between gram-positive and gram-negative bacteria? - Gram-positive and gram-negative bacteria differ in their cell wall structure and their reaction to the Gram stain. Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall that retains the purple dye, while gram-negative bacteria have a thin layer of peptidoglycan and an outer membrane that prevents the dye from entering. Gram-negative bacteria appear pink after counterstaining with safranin. 4. What are some examples of diseases caused by fungi and how are they diagnosed? - Some examples of diseases caused by fungi are candidiasis (thrush), aspergillosis (lung infection), blastomycosis (skin and lung infection), and cryptococcosis (meningitis). They are diagnosed by microscopic examination of samples, culture on specific media, or serological tests for antibodies or antigens.