The main responsible for the delay among the atrial and
ventricular contractions is the action potential conduction velocity of the AV
node cells. If the atria and ventricles contract simultaneously, atria cannot
give any help in filling the ventricles, which is needed, especially in those
with stiff ventricles as in the elderly. Hence atria have to contract first and
then the ventricles.
Fluid, rolling, air resistance, and not sure about the last one.
Answer:
Endocytosis is a form of active transport hence require enegry powered by ATP. The amoeba needs to change shape and engulf and envaginate the particle and then use vessicle transportation to get the materials into the cell. This requires that the cytoskeleton - composed of tubules and filaments - contracts and relax accordingly. This requires energy by ATPs just like the myosin and actin of muscle.
Phagocytosis, another form of endocytosis, is used by some cells such as immune cells to engulf foreign material and then destroy them by use of lysozymes. This is how phagocytes protect the body from invaders.
3.5 cause of the kilometers you have to reduce hope that helps.
