Activated sludge should have the ability to settle quickly so that it can
1. | be rapidly pumped back from the sedimentation tank to the aeration tank |
2. | absorb pathogenic bacteria present in wastewater while sinking to the bottom of the settling tank |
3. | be discarded and anaerobically digested |
4. | absorb colloidal organic matter |
Methanogens do not produce
1. oxygen
2. methane
3. hydrogen sulphide
4. carbon dioxide
The residue left after methane production from cattle dung is
1. burnt
2. buried in land fills
3. used as manure
4. used in civil construction
Big holes in Swiss cheese are made by a
1. | a machine |
2. | a bacterium that produces methane gas |
3. | a bacterium producing a large amount of carbon dioxide |
4. | a fungus that releases a lot of gases during its metabolic activities |
Which one of the following is not a nitrogen-fixing organism?
1. Anabaena
2. Nostoc
3. Azotobacter
4. Pseudomonas
Mycorrhiza does not help the host plant in
1. enhancing its phosphorus uptake capacity
2. increasing its tolerance to drought
3. enhancing its resistance to root pathogens
4. increasing its resistance to insects
What would happen if oxygen availability to activated sludge flocs is reduced?
1. | It will slow down the rate of degradation of organic matter. |
2. | The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs. |
3. | Floes would increase in size as anaerobic bacteria would grow around floes. |
4. | Protozoa would grow in large numbers. |
The free-livings fungus Trichoderma can be used for
1. killing insects
2. biological control of plant diseases
3. controlling butterfly caterpillars
4. producing antibiotics
The technology of biogas production from cow dung was developed in India largely due to the efforts of
1. | Gas Authority of India |
2. | Oil and Natural Gas Commission |
3. | Indian Agricultural Research Institute, Khadi and Village Industries Commission |
4. | Indian Oil Corporation |
Which one of the following alcoholic drinks is produced without distillation?
1. Wine
2. Whisky
3. Rum
4. Brandy