Question

what are the principle biological system of earth ?

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Answer 1

Explanation:

There are four principal biological systems of the earth. They are fisheries, forests, grasslands and croplands. They form the foundation of the global economic system.  Human demands on these systems are increasing to a point where their productivity is impaired.

Answer 2

Explanation:

The earth has four principal biological systems. These are: fisheries, forests, grasslands and croplands. They form the basis of the world's economic system.

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