Practice question

Microplastics are ingested or taken up by marine organisms and can remain in digestive tracts or move, especially at very small sizes, into tissues. This creates tissue contamination and may expose cells to physical irritation, polymer additives, and chemicals carried on particle surfaces. The ecological consequences depend on dose, size, polymer, and organism; microplastics do not generally enhance photosynthesis or undergo rapid biodegradation. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing. Particle size, shape, polymer type, weathering state, and associated chemicals all influence uptake and biological response, so microplastics are not a uniform toxicant. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem.