Final answer:
When short regions of RNA form base-pairs, they create a hairpin structure, which is formed when the RNA molecule folds back on itself and forms intramolecular hydrogen bonds between complementary nucleotides.
Step-by-step explanation:
When short regions of RNA form base-pairs, they create a structure called a hairpin structure. This structure occurs when the RNA molecule folds back on itself and forms intramolecular hydrogen bonds between complementary nucleotides.
The hairpin structure is stabilized by these base pairs and plays an important role in the function of RNA molecules.