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