External Parasites are organisms that live on or obtain nutrients from another organism called a host. Which term describes organisms that live on or obtain nutrients from another organism?

• A. External Parasites
• B. Endosymbionts
• C. Biofilms
• D. Pathogens

Answer: (A)

Parasitism describes a relationship where one organism benefits by obtaining nutrients from another organism, which serves as the host. When these organisms live on the exterior of the host, they are called external parasites. This term directly captures both the feeding/nutrient aspect and the outside-on-the-host position, matching the description given.

Endosymbionts live inside the host, not on the outside. Biofilms are surface-adhered communities, not a single mode of living. Pathogens are disease-causing agents, which can overlap with parasites but don’t inherently specify living on the exterior and feeding from the host. External parasites best fit the description of organisms that live on or obtain nutrients from another organism.