active transport. The movement of ions or molecules across a cell membrane in the direction opposite that of diffusion, that is, from an area of lower concentration to one of higher concentration. Active transport requires the assistance of a type of protein called a carrier protein, using energy supplied by ATP.
the surface area of a figure in square units is the number of unit square it takes to cover entire surface without the gas or overlapse if three dimensional figure has + sides the sides called faces the surface area is the total of the area of the faces
Calcite occurs in igneous, metamorphic, and sedimentary rocks and is the most commonly encountered carbonate mineral.
