What is an effect of excess ionizing radiation on living cells?

Excess ionizing radiation has well-documented effects on living cells, one of which is the induction of mutations in DNA. Ionizing radiation carries enough energy to remove tightly bound electrons from atoms, leading to the ionization of molecules, including DNA. This process can cause various types of DNA damage, such as single-strand breaks, double-strand breaks, crosslinking of DNA strands, or even the formation of reactive oxygen species that further damage nucleic acids.

When the DNA is damaged, the cell may attempt to repair it. However, these repair processes are not always perfect, and they can lead to alterations in the genetic code, hence resulting in mutations. If these mutations occur in critical genes that control cell growth and division, they can have significant biological consequences, such as the potential for cancer development or other cellular dysfunctions.

In contrast, the other options suggest positive effects that are generally not associated with the exposure to high levels of ionizing radiation. Enhanced cellular repair rates, improvement in cell function, and increased enzyme activity do not occur as a direct effect of excessive radiation exposure. In fact, high levels of radiation typically overwhelm the cell's repair mechanisms, leading to detrimental effects rather than any improvements in cellular performance or function.