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Assertion: Oceans are a low productivity...

Assertion: Oceans are a low productivity ecosystems despite occupying about 70% of the earth surface.
Reason: In aquatic ecosystems, productivity is limited by light which decreases with increasing water depth.

A

a) Both assertion and reason are correct and reason is the correct explanation for Assertion.

B

b) Both assertion and reason are correct but reason is not the correct explanation for assertion.

C

c) Assertion is correct but reason is incorrect.

D

d) Both assertion and reason are incorrect.

Text Solution

Verified by Experts

The correct Answer is:
A
Productivity levels of an ecosystem depend upon plant species inhabiting a particular area, their photosynthetic capacity, availability of nutrients, sunlight, moisture and a variety of other environmental factors. The annual net primary productivity of the whole biosphere is approx. 170 billion tons (dry weight) of organic matter. Of this, despite occupying about 70 % of earth's surface, oceans contribute only 32 % of the total productivity (55 billion tons out of 170 billion tons). Thus, oceans are a low productivity ecosystems. It is because in oceans, productivity is limited by light which decreases with increasing water depth.
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