Which of the following is non symbiotic bio-fertilizer

• YAM

• Anabaena

• Azotobacter

• Rhizobium

C.

Azotobacter

Anabaena, Nostoc, Aulosira etc., are agriculturally very important as non-symbiotic bacteria also called free living nitrogen fixing bacteria. VAM, Azotobacter and Rhizobium are symbiotic organisms.

The internal characteristic features of Class- Mammalia are:

(i) Body cavity is divided by a muscular diaphragm between thorax and abdomen.

(ii) Body is maintained at a hugh and constant temperature by means of internal regulation.

In this system, both local and imported fish, a combination of five or six fish species is used in a single fish pond. These species are selected so that they do not compete for food among them by having different types of food habitats.

Advantages:

1. Increases the yield of fish.
2. Helps in maximum fish production.
3. Availability for consumption.
4. Can help farmers increase their financial position.
5. Also creates employment for skilled and unskilled youths.