What effect does radiation have on living organisms?

Radiation has the most significant effect on living organisms by causing ionisation in living tissue. This occurs when high-energy radiation interacts with atoms and molecules in cells, leading to the ejection of electrons from these atoms. The ionisation can cause damage at the molecular level, particularly to DNA, which can result in mutations, cell death, or cancer if the damage is not properly repaired.

Unlike options suggesting that radiation always heals cells or enhances cellular activity, these are misleading as radiation usually introduces harm. The assertion that radiation has no effect on water-based tissues is also incorrect, as water is a significant component of biological tissues and can be directly affected by ionising radiation. Thus, the understanding of radiation's role is crucial, especially in fields like medicine where radiation is used both for treatment and diagnostic purposes.