MCQs on Soil Microbiology, Fermentation, and Food Microbiology for ICAR (SRF or JRF) /ASRB /CSIR NET/BET Exams #1

 

1. Adding nitrogen fertilizer to a compost pile will ____ the decomposition rate and ______ humus production.
   (A) Increase, increase
   (B) Slow, increase
   (C) Increase, decrease
   (D) Slow, decrease

2. Fastest decomposition rate in soil is expected with residues having:
   (A) Lowest N content
   (B) Widest C:N ratio
   (C) Lowest C:N ratio
   (D) Highest C content

3. Which pool in the global carbon cycle uses biochemical energy from reduced carbon compounds?
   (A) Heterotrophs
   (B) Autotrophs
   (C) Carbon dioxide
   (D) Soil organic matter

4. Which of the following species or genera is a frequent contaminant of water supplies?
   (A) Lactobacillus
   (B) Streptococcus
   (C) Pseudomonas
   (D) Clostridium

5. Contemporary milk pasteurization times and temperatures have been selected because they will destroy:
   (A) Mycobacterium tuberculosis
   (B) Coxiella burnetii
   (C) Streptococcus faecalis
   (D) Bacillus anthracis

6. The majority of "swollen" cans observed in the marketplace are the result of:
   (A) CO₂ production by clostridia
   (B) H₂ production by clostridia
   (C) H₂ production from the interaction of tin and acid
   (D) O₂ production by aerobic sporeformers

7. The microorganisms most frequently involved in the spoilage of canned foods are:
   (A) Streptococci and lactobacilli
   (B) Leuconostoc and Pseudomonas
   (C) Clostridium and Bacillus
   (D) Saccharomyces and Staphylococcus

8. If an organism has a water activity of 0.62, in which of the following foods (water activity in parentheses) will it most likely grow?
   (A) Flour (0.61)
   (B) Chocolate (0.54)
   (C) Fresh meat (0.98)
   (D) Honey (0.50)

9. The predominant group of microorganisms found in milk today are:
   (A) Mycobacteria
   (B) Brucella
   (C) Gram-negative rods
   (D) Lactobacilli and streptococci

10. During fermentation, pyruvic acid is converted into major organic products such as:
    (A) Glucose and maltose
    (B) Starch and cellulose
    (C) Ethyl alcohol and lactic acid
    (D) Citric acid and isocitric acid

11. The group of organisms most frequently associated with the production of antibiotics is:
    (A) Actinomyces
    (B) Klebsiella
    (C) Streptomyces
    (D) Pseudomonas

12. Maximum production of antibiotics generally occurs:
    (A) During the log phase
    (B) After the log phase
    (C) Before the log phase
    (D) Only when the pH drops below 4.3

13. The precursor added to a fermenting medium for penicillin G production is:
    (A) Phenylacetic acid
    (B) Tryptophan
    (C) Yeast extract
    (D) Lysine