Energy Flow in an Ecosystem — Maharashtra (SSC) Class 9 Science Solutions (Free)

A food chain is a linear sequence of organisms where energy flows from one organism to the next through feeding relationships. Example: Grass → Grasshopper → Frog → Snake. Each organism is a link in the chain, and energy is transferred from the producer (plant) through consumers at different levels.

Trophic levels are the different feeding positions in a food chain. Producers (plants) are at the first trophic level and convert sunlight into chemical energy. Consumers feed on other organisms: primary consumers (herbivores) eat producers, secondary consumers (carnivores) eat primary consumers, and tertiary consumers eat secondary consumers.

An energy pyramid is a graphical representation showing energy distribution across trophic levels. Energy decreases at each level because: (1) only 10% of energy from one level passes to the next, (2) the rest is lost as heat during respiration, movement, and metabolic activities, (3) some energy is not consumed. This is why ecosystems can support fewer organisms at higher trophic levels.

Decomposers (bacteria and fungi) break down dead organic matter from all trophic levels, releasing nutrients back into the soil for plants to use. They obtain energy from dead organisms and return inorganic nutrients to the ecosystem, completing the nutrient cycle and maintaining ecosystem balance.

Only about 10% of energy is transferred from one trophic level to the next. The remaining 90% is lost because: (1) much energy is used by organisms for respiration and body maintenance, (2) some energy is lost as heat, (3) not all parts of an organism are consumed, and (4) energy is needed for growth and reproduction, making ecosystems pyramidal in structure.