Which statement is true about somatic mutations?

• A. Somatic mutations are inherited by offspring
• B. Germline mutations occur only in somatic cells
• C. Mosaicism cannot arise from somatic mutations
• D. Somatic mutations are not heritable but can cause mosaicism

Answer: (D)

The true statement hinges on how mutations in different cell types behave. Somatic mutations occur in non-reproductive (somatic) cells after fertilization, so they are not passed to offspring because they aren’t in the germ cells that form sperm or eggs. Yet if such a mutation happens early enough in development, its descendants can populate a portion of the body, creating mosaicism—two or more genetically distinct cell populations within the same individual. That’s why somatic mutations aren’t heritable, but they can produce mosaic patterns. Inheritance requires a mutation in the germline, not in somatic tissues, and germline mutations are the ones that can be transmitted to the next generation. The idea that germline mutations occur only in somatic cells is incorrect, and mosaicism arising from somatic mutations is possible, so those options don’t fit.