Biomagnification refers to what phenomenon?

• A. A decrease in chemical concentration up the food chain
• B. The spread of pollutants equally through an ecosystem
• C. The increase in chemical concentration in animal tissues as the chemical moves up the food chain
• D. The dilution of contaminants in water

Answer: (C)

Biomagnification is about the amount of a persistent pollutant increasing in organisms as you move up the food chain. When a stable, fat-loving chemical gets into the environment, small organisms absorb it and store it in their bodies, and it isn’t easily broken down or excreted. As predators eat many contaminated prey, they accumulate more of the chemical in their tissues. Over time, top predators can have much higher concentrations than organisms at lower levels—sometimes dramatically so. This is why mercury in fish or PCBs in marine predators can pose greater risks to species higher up the food chain and even to humans who eat those organisms.

Choices that describe a decrease in concentration, an equal spread through the ecosystem, or dilution do not fit this pattern, because biomagnification specifically involves increasing concentration as you go up trophic levels.