The MCAT is not going to be brutal about thermodynamic cycles and the Carnot cycle. Try to internalize the main ideas, how the Carnot cycle shows that something spontaneous, like heat flowing from a hot body to a cold body, can be coupled to something nonspontaneous, ie. thermodynamic work, up to the point that the entropy of the universe doesn't start to actually decrease. The model for this is the reversible Carnot engine. Walking this path will help you understand the meaning of Gibbs free energy, which actually is one of the most important concepts to bring to the MCAT.