The symbiotic relationship where one organism benefits and the other is harmed is called parasitism.

Here's a breakdown:

* Parasite: The organism that benefits from the relationship.

* Host: The organism that is harmed.

Some examples of parasitism include:

* Ticks on a dog: The tick feeds on the dog's blood, causing discomfort and potential disease.

* Tapeworms in humans: The tapeworm lives in the human intestines and absorbs nutrients from its host.

* Mistletoe on a tree: Mistletoe obtains water and nutrients from the tree, weakening it.