One of the major classes of organic compounds?

When listening the levels of orginization in orginisims from the smallest to most complex , which level is just below organs in complexity

What happens to the average kinetic energy of water molecules as water freezes?

Which example best describes a reflex action? a. eating food when hungry b. coughing when the throat is irritated c. bending down to lift a heavy object d. going for a walk outside