Question

What are the principal biological systems of the earth? How are they useful to us?

Answer 1

Explanation:

There are four principal biological systems of the earth.

These systems are fisheries, forests, grasslands and croplands. In addition to supplying our food, these four systems provide virtually all the raw material for the industry. ... Grasslands have been turned into deserts and production of crops is decreasing.

Answer 2

Answer:

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☆There are four principal biological systems of the earth. These systems are fisheries, forests, grasslands and croplands. In addition to supplying our food, these four systems provide virtually all the raw material for the industry. ... Grasslands have been turned into deserts and production of crops is decreasing.