Question

inserting a normal gene into a patient with a defective gene is called therapy.

Explanation:

The problem is about a medical and biological concept. Gene therapy involves inserting a normal gene into a patient with a defective gene to treat genetic disorders. This falls under the subfield of Biology (or Medicine and Health) in Natural Science. The key term here is "gene" therapy, where the normal gene is introduced to replace or supplement a defective one.

Answer:

gene