Name what each arrow means and follow a change through one link at a time.
Follow a path in the direction of its arrows
A diagram labels its arrows from food to consumer. A seed feeds an insect and the insect feeds a bird. Fewer seeds could reduce insect food, which may reduce the insects available to the bird. If the diagram also shows the bird eating fruit, the effect on the bird depends in part on the amount of fruit available.
To reason about a predator decline, walk backward from the predator once to identify the prey that may experience less predation. Then trace consequences forward through the prey’s own actions. A predicted direction depends on the stated conditions; a diagram alone gives neither a fixed percentage nor a future population count.
Find the response that returns to the starting variable
A temperature model activates heat production when temperature falls. The new heat changes the measured temperature, reducing the deviation that triggered it. This is feedback because the outcome loops back to the measured condition.
Check where a break occurs. A working detector does not ensure a working response. By contrast, a one-way food link describes a transfer without, on its own, showing how a change returns to the first variable.
Apply the guide
A model fish eats larvae and tiny crustaceans. Larvae decline. What can you infer about the second food source?Reveal explanation
It is another depicted food pathway if it remains available; the diagram alone gives no replacement amount.
A detector signals low temperature, but the actuator fails. Which part of the loop can still operate?Reveal explanation
Detection and signaling can still operate, while the corrective heating response fails.
Turn the idea into practice.
Apply the rule to a new case, then explain your choice.
Practice this skillSources & authorship
Sources support scientific principles. Practice scenarios and teaching examples are original.
Original OpenExam guide
Independent educator review is pending. This guide is not an official exam paper or a video transcript.
OpenStax Biology 2e 46.2 Energy Flow through EcosystemsOpenStax Biology 2e 33.3 Homeostasis