When have the intentions to analyze the sea floor an try to measure the difference of materials present on the seafloor we woulds see or analyze that if we are moving away from the land outwards into the deep down ocean then we would see the sequence of the in the following way continental shelf - continental slope - abyssal plain.
Cell transport is useful because it's, essentially, the movement of cells across the blood/veins. Active transport uses energy, while passive transport does not.
