Final answer:
Thymine dimers form between adjacent thymine bases in the UV-induced thymine dimer. They can be repaired through nucleotide excision.
Step-by-step explanation:
When two adjacent thymine bases are exposed to UV light, they can form thymine dimers.
Thymine dimers are covalent bonds between the adjacent thymine bases, which distort the DNA helix.
These dimers can be repaired through a process called nucleotide excision, where the damaged section of DNA is excised and replaced.