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a chemical messenger produced and released by a cell or a gland in one part of the body of the organism that affect cells in other parts of the organism. In essence, it is a chemical messenger that transports a signal from one cell to another. Only a small amount of hormone is required to alter cell metabolism. Hormones in animals are most often transported in the blood.
unicellular organisms that contain a true nucleus and membrane bound organelles. All protists...
the deposition or build-up of silt and organic matter on the beds of rivers, dams etc.
the part of the atmosphere that contains the ozone layer and is about 10 km above the Earth's...