What describes plankton?

What describes plankton?

• A. Large aquatic plants
• B. Tiny organisms that drift in water, serving as a crucial part of the aquatic food web
• C. Bacteria that cause disease
• D. Particles of sediment

Answer: (B)

Plankton are tiny organisms that drift with water currents rather than swimming actively. This drifting lifestyle makes them the foundation of aquatic food webs: phytoplankton photosynthesize and create the energy and oxygen that fuel the ecosystem, while zooplankton feed on phytoplankton and, in turn, are eaten by larger aquatic animals. That combination of being small, drifting, and forming the base of the food chain is exactly what the description captures.

Large aquatic plants aren’t plankton because they’re macroscopic and anchored rather than drifting. Particles of sediment are nonliving material that settles out of the water, not living organisms that form a living, energy-producing base for the food web. Bacteria that cause disease refers to specific pathogens, not the broad, drifting organisms that make up plankton.