Chemotherapy Biotherapy Certification ONS Practice Test 2025 - Free Practice Questions and Study Guide

Anti-tumor antibiotics primarily exert their effects by interfering with nucleic acid duplication. These agents, such as doxorubicin and bleomycin, bind to DNA and disrupt the process of replication and transcription. This interaction ultimately prevents cancer cells from replicating their DNA, leading to cellular death.

The other options provided do describe various mechanisms of action for different classes of chemotherapy drugs, but they do not accurately reflect the primary mechanism employed by anti-tumor antibiotics. Inhibition of RNA synthesis is more characteristic of certain other types of chemotherapeutic agents or antiviral drugs. Blocking enzymes necessary for DNA synthesis typically refers to drugs that target specific enzymes involved in the DNA replication process, such as topoisomerase inhibitors or antimetabolites. Altering cellular oxygen levels is not a mechanism employed by anti-tumor antibiotics; rather, it can be a broader concept in cancer biology relating to tumor microenvironments. Therefore, the accurate choice highlights how anti-tumor antibiotics specifically disrupt the duplication of nucleic acids to hinder tumor growth.