Which characteristic of cells makes them more radiosensitive?

• A. Low metabolic rate.
• B. Shorter mitotic duration.
• C. High specialization.
• D. High reproductive rate.

Answer: (D)

Radiosensitivity is greatest in cells that divide rapidly. Ionizing radiation damages DNA, and cells rely on accurate DNA replication during division. When cells are rapidly proliferating, they pass through replication and division cycles frequently, leaving less time for repair of radiation-induced DNA damage. This means damaged cells are more likely to fail to complete division or undergo cell death, increasing tissue damage in those rapidly renewing populations. That’s why tissues with high turnover, such as bone marrow, the lining of the gut, and reproductive cells, are particularly radiosensitive. In contrast, cells that are more differentiated and divide less often are more resistant because they encounter radiation damage less frequently during replication and have more opportunity for repair between divisions.