Question

Assertion : Eutrophication shows increase in productivity in water.

Reason : With increasing eutrophication, the diversity of the phytoplankton increases.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

The correct option is B If both assertion and reason are true but reason is not the correct explanation of assertion

Eutrophication is a natural process. It is a seen in lakes and ponds which have a rich supply of nutrients. Eutrophication levels increase when abnormally high amount of nutrient from sewage, fertilizers, animal wastage and detergent, enter streams and lakes causing excessive growth or blooms of
microorganisms. With increasing eutrophication, the diversity of the phytoplankton community of a lake increases and the lake finally becomes dominated by blue - green algae. But on further increase there is a lowering of diversity.

Therefore both the statements are true, but the reason is not the correct one. This is because the increase in productivity is due to the increase in biomass and not biodiversity.