Describe Two examples of how Kingdom Protista is helpful (two examples) and how it is harmful (two examples).

Members of the Kingdom Protista make up a good share of
the phytoplankton that occupy the top few meters of the world's oceans. There they form
the basis of the ocean's food chain, capturing sunlight and converting it into useable
biological molecules.  Another important ecological role of protists is in oxygen
production; the ocean's phytoplankton create about half of all the oxygen in Earth's
atmosphere.

Protists can be harmful becuase some of them
can cause diseases. href="http://www.ncbi.nlm.nih.gov/books/NBK8584/">Malaria is caused by the
protist Plasmodium falciparum. The sexually transmitted disease
trichomoniasis
is caused by Trichomoniasis vaginalis. href="http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001333/">Giardiasis, an
uncomfortable intestinal condition, is caused by the protist Giardia
lamblia.