Antibiotics are usually derived from bacteria.
Seaweed is a type of algae.
Explanation: Seaweeds are a group of photoautotrophic, multi-cellular algae occurring in marine environments.
The generalization that all organisms are composed of cells was established through multiple observations in various kinds of animals and plants. A controlled experiment of finding cells in all the kinds of living organisms is not possible or is infeasible as it will require prior knowledge of all the kinds of organisms inhabiting Earth and the effort to catch and bring them in the controlled environment of the lab for testing.
