Chapter 5, Problem 5STP

Summary Introduction

Introduction :

Pond or lake is an inland body of standing water. Lake or pond can be as big as thousands of square meters or as small as a few square meters. Some water bodies might be covered by water for a few weeks or months, while some lakes have existed for many years. There are three zones in lakes and ponds based on the amount of sunlight that penetrates the water. These zones are littoral zone, limnetic zone, and profundal zone.

Answer to Problem 5STP

Correct answer :

The correct answer is option (C) debris from dead organisms.

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) debris from dead organisms. The deepest area of a large lake is known as the profundal zone. This zone is very much colder and oxygen is lower than the other zones. Little light is able to penetrate the limnetic zone in order to enter the profundal zone. Debris from dead organisms is found in this zone. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) algae. Algae are found in the littoral zone of a lake. The area closest to the shore is the littoral zone. The water in this zone is shallow, which allows sunlight to reach the bottom. Aquatic plants, algae live in this shallow water. So, this is an incorrect option.

Option (B) plankton. Plankton is found in the limnetic zone of a lake. The limnetic zone is the open water that is well lit and is dominated by plankton. So, this is an incorrect answer.

Option (D) floating water plants. Floating water plants are found in the littoral zone of a lake. These plants are live in shallow water and littoral zone has shallow water. So, this is an incorrect answer.