[ 355 ] Life Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Refer to the following passage to answer the next three questions. In a marine ecosystem, there is a unique relationship between corals and the photosynthetic protists that live on the coral reefs. The single-celled protists, called zooxanthellae, live in the tissue of corals and transform large amounts of carbon dioxide into usable energy. The photosynthetic products are used by the corals for metabolic functions or as building blocks in the making of proteins, fats, and carbohydrates. Although many of a coral’s energy needs are supplied by these zooxanthellae, most corals also capture food particles with their stinging tentacles. Prey ranges in size from small fish to microscopic zooplankton. These food sources supply corals and zooxanthellae with nitrogen. Based on the passage, corals and zooxanthellae demonstrate which type of symbiotic relationship? A. mutualism B. parasitism C. amensalism D. commensalism