Texas A&M University (TAMU) BIOL112 Introductory Biology II Lab Exam 1 Practice Exam

Commensalism is a type of ecological relationship that involves two different species where one species benefits from the interaction while the other species experiences neither gain nor loss. This means that for the benefiting species, there are clear advantages, such as access to food or habitat, while the second species remains unaffected. An example of commensalism is barnacles attaching themselves to the shell of a turtle; the barnacles gain a place to live and access to food in the water, while the turtle is not significantly impacted by their presence. This definition aligns perfectly with the selected answer.

In contrast, the other relationships described are not characteristic of commensalism. In mutualism, both species benefit from the interaction, which is distinct from the one-sided benefit seen in commensalism. Parasitism, on the other hand, involves one species benefiting at the expense of the other, which is not applicable here. Lastly, competition refers to a scenario where species vie for limited resources, leading to harm for both parties involved, which does not describe the neutral aspect found in commensalism.