What gases are produced in anaerobic sludge digesters?

1. Methane and CO₂ only

2. Methane, Hydrogen sulphide and CO₂

3. Methane, hydrogen sulphide and O₂

4. Hydrogen sulphide and CO₂

A good producer of citric acid is

1. Aspergillus

2. Pseudomonas

3. Clostridium

4. Saccharomyces

During sewage treatment, biogases are produced, which include

1. methane, hydrogen sulphide and carbon dioxide

2. methane, oxygen and hydrogen sulphide

3. hydrogen sulphide, methane and sulphur dioxide

4. hydrogen sulphide, nitrogen and methane

Monascus purpureus is a yeast used commercially in the production of

(1) ethanol

(2) streptokinase for removing clots from the blood vessels.

(3) citric acid

(4) blood cholesterol lowering statins.

Which one of the following microbes forms symbiotic association with plants and helps them in their nutrition?

(1) Azotobacter

(2) Aspergillus

(3) Glomus

(4) Trichoderma

Yeast is used in the production of

(1) citric acid and lactic acid

(2) lipase and pectinase

(3) bread and beer

(4) cheese and butter

Which one of the following helps in absorption of phosphorus from soil by plants?

1. Rhizobium

2. Anabaena

3. Frankia

4. Glomus

Secondary sewage treatment is mainly a

(1) mechanical process

(2) chemical process

(3) biological process

(4) physical process

The most common substrate used in distilleries for the production of ethanol is

(1) soya meal

(2) ground gram

(3) molasses

(4) corn meal

Select the correct statement from the following

(1) Biogas is produced by the activity of aerobic bacteria on animal waste

(2) Methanobacterium is an aerobic bacterium found in rumen of cattle.

(3) Biogas, commonly called gobar gas, is pure methane

(4) Activated sludge-sediment in settlement tanks of sewage treatment plant is a right source of aerobic bacteria