Which term describes the buildup of a pesticide in an organism due to uptake from water or food?

• A. Bioconcentration
• B. Leaching
• C. Photodecomposition
• D. Volatilization

Answer: (A)

The buildup described happens when a pesticide moves from the surrounding water into the organism and accumulates there, reaching higher levels than in the water. This is known as bioconcentration. It captures the idea of direct uptake from the surrounding medium—typically water in aquatic organisms—through interfaces like gills or skin, and retention in the organism’s tissues. The rate and extent depend on how readily the chemical crosses membranes, its affinity for lipids, and how long the organism is exposed.

Leaching refers to movement of the chemical through soil, not uptake by an organism. Photodecomposition is the breakdown of the pesticide by sunlight. Volatilization is the loss of the chemical to the air. Those processes don’t describe the accumulation inside an organism from its environment, which is why they’re not the correct terms here.

Note that bioaccumulation is the broader idea of buildup from all sources (water, food, air), and biomagnification describes increasing concentrations up the food chain. The term bioconcentration specifically emphasizes uptake from the surrounding environment, typically water, leading to higher internal concentrations.