Final answer:
Plankton is a group of organisms that float or drift in bodies of water. It includes both plants and animals. Diatoms are important members of the phytoplankton community.
Step-by-step explanation:
Plankton refers to the diverse group of organisms that float or drift in bodies of water, unable to swim against the current. They can be microscopic or larger, and include both plants (phytoplankton) and animals (zooplankton). Diatoms are an important component of the phytoplankton community, which are photosynthetic organisms that form the base of aquatic food chains.