Overview of Heat and Temperature
The concepts of Heat and Temperature are applied much more loosely in everyday life than in formal scientific discussion. In physics and chemistry, heat energy refers to thermal energy which is transfered from one object to another. In other words, heat energy is not the internal energy, or even the thermal energy of any object. Heat energy refers to the energy which is transfered in the process of heat flow. When you want to discuss the energy of particle motion within a substance itself, employ the concept of thermal energy, not heat. Thermal energy is the portion of an object's internal energy due to the object being at a temperature greater than absolute zero.

Temperature is also an everyday idea that has important conceptual substance in science. An object's temperature is an intrinsic property, but it can also be defined extrinsically, as predicting the direction of heat flow between objects. Reconciling the approaches to temperature within thermodynamics is a primary conceptual arc. For a single object, the temperature is a quantity that goes up or down with the average kinetic energy per particle. However, the particles of some substances have more places to put thermal energy (translation, vibration, rotation, etc) so the temperature is not a strict measure of kinetic energy per particle, but a measure of thermal energy per degree of freedom. The temperature difference between one object and another predicts the direction that heat will spontaneously flow. Heat flows spontaneously from a higher temperature object to a lower temperature object.

Heat and Temperature on the MCAT
In addition to being important, fundamental material, Heat and Temperature is one of those topics where the basics do also appear in a straightforward way on the MCAT. While understanding this material is crucial to understanding what comes later in chemistry and biology, you also need to make sure to master fundamental problem solving in areas such as heat capacity, temperature scales, or heat transfer.