The answer is Protein. T<span>he primary type of macromolecule in the actin and myosin that make up muscle cells is Protein. </span>Muscles<span> are composed of two major protein filaments: a thick filament composed of the protein </span>myosin<span> and a thin filament composed of the protein </span>actin<span>. </span>Muscle contraction<span> occurs when these filaments slide over one another in a series of repetitive events.</span>
According to the relationship between force and acceleration, described in Newton's 2nd law of motion, increasing the force of the object would also increase the objects acceleration in the same direction to which the force is applied. It essentially starts to move even faster, than it had been before. Since the object is accelerating it changing its speed at an even faster rate.
Much like with fish, gills enable tadpoles to breathe in the water.
