Chapter 4, Problem 3STP

Summary Introduction

Introduction:

An area filled with water and surrounded by land is known as a lake. A lake may be natural or manmade and rivers and streams feed or drain the lake. The water in a lake does not flow like rivers but rivers either flow into or out of the lake.

Answer to Problem 3STP

Correct answer :

The correct answer is option (B) a lake in the crater of a volcanic mountain.

Explanation of Solution

Explanation/justification for the correct answer :

Option ((B). a lake in the crater of a volcanic mountain. When a lake is formed in a crater that was formed as a result from explosion or collapsing activity of a volcanic mountain is known as Crater Lake.

The environment of a crater lake is unstable and quite susceptible to small amount of variations. The water is deep, clear with very less vegetation. These type of lakes are situated away from populated area. So, the correct answer is option (B).

Explanation for incorrect answer :

Option (A). a lake formed by a winding river. A lake formed by a winding river is called an oxbow lake. It is a crescent shaped lake and is created due to deposition and erosion caused by change of a river’s course. The productivity of the lake is high as there are regular influxes of nutrients. So, this is an incorrect answer.

Option (C). a lake near the mouth of the river. A lake near the mouth of the river is the place where a river enters a lake, larger river or ocean. During its flow, the river picks up sediments and deposits them near the mouth of the river. Due to a large amount of alluvium deposition, the area shows good fish productivity and often, is a good fishing ground. So, this is an incorrect answer.

Option (D). a lake where algal bloom kills the fishes. In certain lakes, the high nutrient levels causes high production of algae known as algal bloom. Excessive algal blooms cover the water surface of the lake. As a result, sunlight cannot reach the lower surface. Algal blooms can also release toxins in the water turning it green, scummy with a bad smell as a result killing the fishes. So, this is an incorrect answer.