Living cells are highly ordered units, yet the universe is heading toward higher entropy. Discuss how life can maintain its order in spite of the second law of thermodynamics. Are we defying this law? Part 2: What is the advantage of using ATP as a common energy source? Another way of asking this question is, Why is ATP an advantage over using a bunch of different food molecules? For example, instead of just having a Na+/K+-ATPase in a cell, why not have a bunch of different ion pumps each driven by a different food molecule, like a Na+/K+-glucosase (a pump that uses glucose), a Na+/K+-sucrase (a pump that uses sucrose), a Na+/K+-fatty acidase (a pump that uses fatty acids), and so on?