Energy and nutrients flow from one trophic level to another in an ecosystem. Which one of the following statements correctly describes the direction of flow of energy and nutrients in an ecosystem?

In an ecosystem, energy flow and nutrient cycling follow distinct physical principles. Energy flow is strictly unidirectional, moving from the sun to producers and then through various trophic levels [2]. According to the laws of thermodynamics, energy is not recycled; instead, it is dissipated as heat at each transfer, making it unavailable to previous levels [3]. In contrast, nutrients (matter) such as carbon, nitrogen, and phosphorus move through cyclic pathways known as biogeochemical cycles [3]. These essential elements are taken up by producers, passed to consumers, and eventually returned to the soil or atmosphere by decomposers, ensuring their continuous reuse within the biosphere. Thus, while energy must be constantly supplied by an external source like the sun, nutrients are maintained in a closed-loop system.

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > 2.1 ENERGY FLOW > p. 11
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 13: Our Environment > 13.1.1 Food Chains and Webs > p. 211
3. [3] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > 1.14 Environment and Ecology > p. 14