Which sequence is NOT a correct pathway of energy through an ecosystem?

Which sequence is NOT a correct pathway of energy through an ecosystem?

• A. bacteria → plants → birds
• B. producers → decomposers → consumers
• C. sunlight → plants → herbivores
• D. producers → primary consumers → secondary consumers

Answer: (A)

Energy moves through ecosystems in one direction: sunlight powers producers, which convert it to chemical energy, and that energy then passes up to herbivores and predators, while decomposers recycle nutrients. The sequence that starts with bacteria isn’t a valid energy pathway because energy does not originate with bacteria feeding plants in a typical food chain; plants obtain their energy from sunlight, not from bacteria, so energy flowing from bacteria to plants to birds misrepresents how energy transfer works. The other sequences align with how energy moves: sunlight → plants → herbivores shows the sun’s energy being captured by producers and then consumed by primary consumers, and producers → primary consumers → secondary consumers shows energy moving through successive trophic levels. A detritus-based path involving decomposers can occur, but it doesn’t depict a straightforward energy transfer to living consumers in a single simple chain.

Energy moves through ecosystems in one direction: sunlight powers producers, which convert it to chemical energy, and that energy then passes up to herbivores and predators, while decomposers recycle nutrients. The sequence that starts with bacteria isn’t a valid energy pathway because energy does not originate with bacteria feeding plants in a typical food chain; plants obtain their energy from sunlight, not from bacteria, so energy flowing from bacteria to plants to birds misrepresents how energy transfer works.

The other sequences align with how energy moves: sunlight → plants → herbivores shows the sun’s energy being captured by producers and then consumed by primary consumers, and producers → primary consumers → secondary consumers shows energy moving through successive trophic levels. A detritus-based path involving decomposers can occur, but it doesn’t depict a straightforward energy transfer to living consumers in a single simple chain.