Practicing Success

Target Exam

CUET

Subject

Biology

Chapter

Environmental Issues

Question:

Which among the following are the prime contaminants of eutrophic lake ?

Options:

Calcium and phosphate

Cadmium and phosphate

Nitrate and phosphate

Calcium and cadmium

Correct Answer:

Nitrate and phosphate

Explanation:

Eutrophication is the natural aging of a lake by nutrient enrichment of its water. In a young lake the water is cold and clear, supporting little life. With time, streams draining into the lake introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic organisms. As the lake’s fertility increases, plant and animal life burgeons, and organic remains begin to be deposited on the lake bottom.

During the past century, lakes in many parts of the earth have been severely eutrophied by sewage and agricultural and industrial wastes. The prime contaminants are nitrates and phosphates, which act as plant nutrients. They overstimulate the growth of algae, causing unsightly scum and unpleasant odours, and robbing the water of dissolved oxygen vital to other aquatic life