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  • Question
  • Sweet and salty foods frequently don't require refrigeration to prevent spoilage because they have


  • Options
  • A. insufficient nutrients
  • B. low pH
  • C. high concentration of solutes
  • D. toxic alkaline chemicals

  • Correct Answer
  • high concentration of solutes 


  • Physical and Chemical Agents problems


    Search Results


    • 1. Which of the following is best to sterilize heat labile solutions?

    • Options
    • A. Dry heat
    • B. Autoclave
    • C. Membrane filtration
    • D. Pasteurization
    • Discuss
    • 2. Which of the following is/are vapour-phase disinfectant/s?

    • Options
    • A. Formaldehyde
    • B. Ethylene oxide
    • C. Both (a) and (b)
    • D. None of these
    • Discuss
    • 3. Bactericidal concentration of phenol is

    • Options
    • A. 0.25%
    • B. 0.5%
    • C. 0.75%
    • D. 1%
    • Discuss
    • 4. Which of the following material is sterilized by heating at 160°C in a hot air oven for one hour?

    • Options
    • A. Swab sticks
    • B. All-glass syringes
    • C. Oils and jellies
    • D. All of these
    • Discuss
    • 5. Which is the most important surface active disinfectants?

    • Options
    • A. Amphoteric compounds
    • B. Cationic compounds
    • C. Non-ionic compounds
    • D. Anionic compounds
    • Discuss
    • 6. Nitrogen fixation by the microorganisms can be detected by adopting the approach of

    • Options
    • A. demonstrating growth in a nitrogen free medium
    • B. cultivating the microorganisms in the presence of nitrogen labeled with isotropic nitrogen
    • C. measuring15N2 by mass spectrometer
    • D. all of the above
    • Discuss
    • 7. Which of the following soil microorganism is involved in the reduction of sulfates to H2S?

    • Options
    • A. Thiobacillus thiooxidans
    • B. Desulfotomaculum
    • C. Rhodospirillum
    • D. Rhodomicrobium
    • Discuss
    • 8. The nitrogenase consists of

    • Options
    • A. dinitrogenase
    • B. dinitrogenase reductase
    • C. both (a) and (b)
    • D. none of these
    • Discuss
    • 9. Denitrification may be distinguished as

    • Options
    • A. dissimilative
    • B. assimilative
    • C. both (a) and (b)
    • D. blue baby syndrome
    • Discuss
    • 10. The organisms responsible for the characteristic musty or earth odor of a freshly plowed field is/are

    • Options
    • A. Nocardia
    • B. Streptomyces
    • C. Micromonospora
    • D. all of these
    • Discuss


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