What is B.O.D.:
1. The amount of $O_2$ utilized by organisms in the water
2. The amount of $O_2$ utilized by microorganisms for decomposition
3. The total amount of $O_2$ present in water
4. All of the above

Which of the following is true pair of biofertilizers:
1.  Azolla and BGA
2.  Nostoc and legume
3.  Rhizobium and grasses
4.  Salmonella & E. Coli

The term "antibiotic" was coined by:

1. Edward Jenner

2. Louis Pasteur

3. Selman Waksman

4. Alexander Fleming

Which of the following plants are used as green manure in crop fields and in sandy soils:

1. Crotalaria juncea and Alhagi camelorum

2. Calotropis procera and Phyllanthus niruri

3. Saccharum munja and Lantana camara

4. Dichanthium annulatum and Azolla nilotica

During anaerobic digestion of organic waste, such as in producing biogas, which one of the following is left undegraded:

1. Lipids

2. Lignin

3. Hemi-cellulose

4. Cellulose

Escherichia coli is used as an indicator organism to determine the pollution of water with:

1. Heavy metals

2. Faecal matter

3. Industrial effluents

4. Pollen of aquatic plants

Which of the following is used to manufacture ethanol from starch:

1. Penicillin

2. Saccharomyces

3. Azotobactor

4. Lactobacillus

During the formation of bread it becomes porous due to the release of CO₂ by the action of:

Which bacteria is utilized in a Gobar gas plant:

1. Methanogens

2. Nitrifying bacteria

3. Ammonifying bacteria

4. Denitrifying bacteria

Which one produces gas by decomposing the gobar (Dung) in gobar gas:
1.  Fungus
2.  Virus
3.  Methanogenic bacteria
4.  Algae