Final answer:
A transversion mutation is a type of point mutation that occurs when a purine is replaced by a pyrimidine or vice versa.
Step-by-step explanation:
A transversion mutation is a type of point mutation that occurs when a purine (adenine and guanine) is replaced by a pyrimidine (thymine and cytosine), or vice versa. For example, if cytosine, a pyrimidine, is replaced by adenine, a purine, it would be a transversion mutation.