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