Answer:
Plant-like protists produce almost one-half of the oxygen on the planet through photosynthesis. Other protists decompose and recycle nutrients that humans need to live. ... For example, medicines made from protists are used in treatment of high blood pressure, digestion problems, ulcers, and arthritis.
But, like any other organism, they can also inflict harm, particularly to humans. Most harmful protists are classified as animal-like protists that act as parasites, or organisms that benefit from causing harm to other organisms.
