An organ or organism that experiences biological harm from relatively low doses of radiation is described as having:

• A. Low Radiosensitivity
• B. High Radiosensitivity
• C. Low Radioactivity
• D. High Radioactivity

Answer: (B)

Radiosensitivity describes how readily tissue is damaged by ionizing radiation. If harm occurs at relatively low doses, the tissue is highly radiosensitive. This happens because certain cells are rapidly dividing, undifferentiated, or metabolically active, which makes their DNA more vulnerable and harder to repair. Classic examples include bone marrow, reproductive cells, and the lining of the gut. The idea, supported by concepts like Bergonie and Tribondeau, is that tissues with high proliferation and low differentiation are more easily damaged by small amounts of radiation, while mature, slowly dividing tissues show more resistance. The term radioactivity, on the other hand, relates to how much radioactive material is emitting radiation, not how sensitive a tissue is to it.