Final answer:
Endogenous agents are internal factors that can damage DNA, while exogenous agents are external factors that can also cause DNA damage.
Step-by-step explanation:
Endogenous agents refer to DNA damage caused by internal cellular processes, such as reactive oxygen species produced during normal metabolic processes. This can result in hydrolysis of bases, mismatches of bases during DNA replication, and other spontaneous mutations. On the other hand, exogenous agents are external factors that can damage DNA, such as UV radiation, X-rays, and certain chemicals. These agents can induce mutations in replicating and non-replicating DNA through mechanisms like base modifications, DNA crosslinking, and DNA strand breaks. However, significant damage or ineffective repair mechanisms can lead to various cellular responses, including senescence, apoptosis, or uncontrolled cell division, which can result in cancer. The efficiency of DNA repair mechanisms can vary depending on factors such as cell type, cell age, and extracellular environment.