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.

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

Which one of the following is not a nitrogen-fixing organism?

1. Anabaena

2. Nostoc

3. Azotobacter

4. Pseudomonas

Big holes in Swiss cheese are made by a

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

Methanogens do not produce

1. oxygen

2. methane

3. hydrogen sulphide

4. carbon dioxide

Activated sludge should have the ability to settle quickly so that it can

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

Which one of the following alcoholic drinks is produced without distillation?

1. Wine

2. Whisky

3. Rum

4. Brandy