Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What is the relationship defined as one organism benefiting while the other is harmed?

1. Mutualism

2. Commensalism

3. Parasitism

4. Predation

The correct answer is: Parasitism

The relationship described in the question is accurately identified as parasitism. In this ecological interaction, one organism, known as the parasite, derives benefits at the expense of another organism, the host. The parasite typically feeds on the host, causing some degree of harm or disadvantage, which can range from minor symptoms to severe health issues or even death for the host depending on the nature and extent of the parasitic relationship. This concept is crucial in understanding ecosystem dynamics, as parasitism impacts population dynamics and community structure in various habitats. The idea of one organism benefitting while the other suffers contrasts distinctly with mutualism, where both organisms benefit, and commensalism, where one organism benefits without affecting the other. Predation involves one organism eating another and can involve a slightly different dynamic, focusing on the predator-prey relationship rather than the long-term harmful association seen in parasitism.