Question

An oligotrophic lake is characterized by
A. Great changes in water level
B. Long food chains
C. Low nutrient contents and little life
D. High nutrient levels and abundant flora and fauna

Answer 1

Hint: Lakes are freshwater biomes. They are often large and deep, up to 100 meters. They have permanent water. The lakes are of two types regarding how much plant life they can support eutrophic and oligotrophic lakes.

Step by step answer:The lakes develop by 3 ways (i) as natural or manmade depressions filled with water, (ii) as a result of glaciations, and (iii) as a cut off the acute bend of Winding River. The lakes formed by the last method are called oxbow lakes.
Oligotrophic lakes:
These are deep lakes with steep rocky sides and narrow littoral zones. They are low in nutrients such as phosphorus, calcium, and nitrogen.
Therefore, they support a few organisms. Their water is usually dark and very clear, and deep water always contains oxygen because there are few organisms to use it.
Some lakes have saline and brackish water like the sambhar lake in Rajasthan. The brackish lakes are oligotrophic.
Hence, the correct answer is option C. Low nutrient and little life

Additional information:
Eutrophic lakes - These are shallow lakes, and are rich in nutrients and life. They have little oxygen because decomposer organisms rapidly use it up, metabolizing the organic matter produced by other organisms. Dal Lake of Kashmir is an example of an eutrophic lake.

Note: The physical factors of lakes depend on the source of water, location, altitude, latitude, and surrounding biome. The small lakes and the peripheral shallow parts of the large lakes have physical factors forms of life almost similar to those found in the ponds. Other freshwater biomes are streams and rivers, ponds, and marshes.