Microbiology MCQs (Quiz 7) Posted on June 8, 2026June 10, 2026Author agropublishers 0 1. What is the main sterilizing agent in an autoclave? Ultraviolet light Chemical disinfectants High-pressure steam Dry heat 2. A microbiologist wants to obtain isolated colonies from a mixed bacterial culture. Which medium would be most appropriate? Nutrient agar plate Buffer solution Sterile water Nutrient broth 3. Agar begins to solidify at temperature ~ ______________°C after cooling from its molten state 15-20 40-45 65-70 90-100 4. Which microscope is most suitable for the routine identification of bacterial cell shape and arrangement in stained preparations? Bright-field microscope Dark-field microscope Transmission electron microscope Scanning electron microscope 5. Joseph Lister applied which scientific principle to reduce surgical infections? Koch’s Postulates Theory of Evolution Cell Theory Pasteur’s Germ Theory 6. The medium containing agar and nutrients is called ___________ Selective medium Solid medium Broth medium Liquid medium 7. Why is air removal essential before sterilization begins in an autoclave? Air reduces steam penetration and effective temperature Air increases microbial growth Air damages equipment Air causes media solidification 8. A bacterium moves away from a disinfectant solution. This is an example of ___________________ Aerotaxis Positive chemotaxis Phototaxis Negative chemotaxis 9. ________________ is the primary source of agar used in microbiological media Marine algae Bacteria Fungi Protozoa 10. A microorganism that uses glucose as both an energy source and a carbon source is classified as a _____________ Chemoheterotroph Phototroph Chemoautotroph Photoautotroph Loading … Question 1 of 10 Microbiology MCQs (Quiz 7)
