Biology 30 – Populations Practice Test

At the heart of a predator-prey interaction is the idea that one organism hunts, kills, and eats another. This dynamic describes energy flowing through the food web where the predator benefits by obtaining food, and the prey is harmed or killed. Because of this, predators often evolve hunting adaptations like sharp teeth, speed, or stealth, while prey evolve defenses such as camouflage, quick escape, warning signals, or group vigilance. This relationship also helps regulate populations and can create characteristic cycles: when prey become plentiful, predator numbers rise, which then reduces prey and causes predator numbers to fall, and so on. Other types of interactions include mutualism (both species benefit), commensalism (one benefits while the other is unaffected), and competition (two species competing for the same resource), but those do not describe the predator-prey dynamic.