In this model chain, algae are eaten by small fish, small fish are eaten by larger fish, and larger fish are eaten by eagles. Which statement describes how energy moves through this chain?
Explanation
Energy flow in a food web is one way: it passes from the algae to each higher feeding level, and part of it leaves as heat at every step. The closest wrong choice, endless circulation, confuses energy flow with nutrient cycling: nutrients are recycled, but energy that has left as heat never comes back to the algae.