Briefly describe how nitrogen of the atmosphere is converted to nitrates by leguminous plants.

State how the nitrates in the soil get converted to nitrogen of the atmosphere.

Draw a diagram showing the Nitrogen cycle and answer the following questions.

(a) Define the terms:

1. Nitrification
2. Denitrification

(b) Distinguish between biological nitrogen fixation and industrial nitrogen fixation.

(c) Name the kind of relationship that exists between Rhizobium and leguminous plants.

Would there be any bacteria in an aquarium ?

(a) A balanced aquarium contains certain animals as well as some plants. How many kinds of animals can you make out in the aquarium shown here. Name any two such animals.

(b) Do you think there would be some bacteria in it? If so in which part of the aquarium would they be occurring in abundance and what for?