Chapter 2, Problem 18A

Summary Introduction

Introduction :

Pond ecosystem refers to the freshwater ecosystem in which various communities of organisms prevail in water which are dependent on each other for their living, which includes nutrition and survival.

Cycle of energy depends on the energy flow through different trophic levels in an ecosystem.

Answer to Problem 18A

Correct answer :

The correct answer is option (b) Through light from the sun.

Explanation of Solution

Explanation/justification for the correct answer :

Option b) through light from the sun. Ponds get their energy from the sun. In other ecosystem, plants are the primary producer which produces energy. In aquatic ecosystem, chlorophyll in the aquatic plants produces food and energy in the presence of sunlight. And this energy is transferred to the ecosystem. Algae is present on the surface of ecosystem, which collects energy from the sunlight and transfer to the other organism of the ecosystem.

Explanation for incorrect answer :

Option a) through growth of algae. Growth of algae results in the transfer of energy to the organisms in the ecosystem. Option c) through decay of dead fishes. Decay of the fishes results in the production of organic matter and energy is released in the surroundings. Option d) through runoff from fields. Runoff from the fields results in the flow of energy from one ecosystem to other.