Final answer:
Dipicolinic acid is the unique chemical compound that is important in the heat resistance of endospores.
Step-by-step explanation:
The unique chemical compound that is important in the heat resistance of endospores is dipicolinic acid. Dipicolinic acid, also known as DPA, is a substance that is found in high concentrations in the core of endospores. It plays a crucial role in stabilizing the DNA within the endospore and protecting it from heat and other harsh conditions.