MCQ: Environmental Microbiology 1st

1. In an ecosystem, autotrophic organisms would be classified as:
   a. Producers     b. Consumers   c. Decomposers           d. Parasites
   e. None of these
2. In an ecosystem, microorganisms are likely to be:
   a. Consumers   b. Producers     c. Decomposers           d. Parasites
   e. All of these
3. What percentage of nitrogen fixed annually on earth is fixed by the action of bacteria?
   a. less than 10%           b. 20%             c. 50%             d. 70%             e. 90%
4. The microorganisms that are the primary symbiotic nitrogen fixers are members of the genus:
   a. Klebsiella      b. Azotobacter             c. Rhizobium                 d. Clostridium  
   e. None of these
5. The form of nitrogen that is most usable in plants is:
   a. Nitrate          b. Nitrite           c. Molecular Nitrogen               d. Ammonia     
   e. Ammonium ions
6. Which of the following forms of nitrogen can be use by microorganisms in place of molecular oxygen?
   a. Ammonium ions        b. Nitrate          c. Molecular nitrogen                d. Ammonia     
   e. None of these
7. Which form of sulfur is most usable by both microorganisms and plants?
   a. Sulfite           b. Hydrogen sulfide       c. Elemental sulfur         d. Sulfate         
   e. None of these
8. All sulfate reducing bacteria are classified as:
   a. Anaerobes    b. Psychrophilic            c. Mesophilic    d. Thermophilic
   e. Halophilic
9. Members of the genus Thiobacillus can produce sulfuric acid by the oxidation of:
   a. Hydrogen sulfide       b. Ferrous sulfide          c. Elemental sulfur         d. All of these
   e. None of these
10. The most numerous group of microorganisms found in soil are the:
    a. Fungi            b. algae            c. protists         d. bacteria        e. viruses
11. Soil microorganisms that are also potential pathogens for humans and other animals are most likely to be members of the genus:
    a. Thiobacillus               b. Rhizobium    c. Clostridium               d. Azotobacter
    e. All of these