Which option is NOT listed as a determinant of cellular sensitivity to radiation?

Which option is NOT listed as a determinant of cellular sensitivity to radiation?

• A. Are young & growing
• B. Reproduce quickly
• C. Are undifferentiated (stem cells)
• D. Are differentiated

Answer: (D)

Radiosensitivity rises with cells that are actively cycling and not yet specialized. Cells that are young and growing, and those that are undifferentiated (stem-like) tend to be in or near DNA synthesis and mitosis, making radiation more likely to cause lethal damage. Reproducing quickly and being undifferentiated reflect this high growth fraction, which is why they are listed as determinants of sensitivity. Differentiated cells, however, are typically more mature and quiescent, with lower mitotic activity and often greater resistance to radiation. Because being differentiated does not contribute to increased sensitivity, that option is the one that doesn’t fit the determinant concept.

Radiosensitivity rises with cells that are actively cycling and not yet specialized. Cells that are young and growing, and those that are undifferentiated (stem-like) tend to be in or near DNA synthesis and mitosis, making radiation more likely to cause lethal damage. Reproducing quickly and being undifferentiated reflect this high growth fraction, which is why they are listed as determinants of sensitivity. Differentiated cells, however, are typically more mature and quiescent, with lower mitotic activity and often greater resistance to radiation. Because being differentiated does not contribute to increased sensitivity, that option is the one that doesn’t fit the determinant concept.