A millibar is a unit of pressure which is most commonly seen in the context of meteorology, where atmospheric pressure is sometimes given in millibars. As the name would suggest, a millibar is equal to one thousandth of a bar.
User: The microscopic organisms at the base of the marine food chain are known as A. plant life. B. terrestrial animals. C. primitive life. D. phytoplankton. Weegy: The microscopic organisms at the base of the marine food chain are known as Phytoplankton. User: In addition to being necessary for respiration, _______ also provides UV radiation protection. A. water B. hydrogen C. oxygen D. carbon dioxide.
Plankton are divided into two groups: phytoplankton (plant forms) and zooplankton (animal forms). Phytoplankton are the base of the marine food chain. They are literally the grass of the sea.Phytoplankton blooms, population explosions, occur when conditions (sunlight level, water temperature, water salinity, etc.) are  right and sufficient phytoplankton biomass and nutrients are available.hytoplankton are the base of the marine food chain. They are literally the grass of the sea. Phytoplankton blooms, population explosions, occur when conditions (sunlight level, water temperature, water salinity, etc.) are  right and sufficient phytoplankton biomass and nutrients are available.