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the movement of molecules across a membrane against the concentration gradient, from an area of lower concentration to an area of higher concentration of a particular molecule, using energy supplied by ATP.
organisms that are unable to produce their own organic food and must therefore obtain nutrients...
middle body tissue layer that forms the muscular, circulatory and excretory systems.
the volume of air that is inhaled and exhaled during normal breathing.
a species that has a large effect on its environment relative to its abundance and plays an...
all the different ecosystems with their numerous and varied organisms.