Final answer:
Peroxisomes are spherical organelles that detoxify harmful substances by oxidation and convert hydrogen peroxide into water and oxygen to prevent cell damage.
Step-by-step explanation:
Spherical membranous organelles in which harmful substances are detoxified by oxidation are called peroxisomes. Peroxisomes are small, round organelles enclosed by single membranes and contain an abundance of enzymes, including catalase, that are primarily responsible for detoxifying harmful substances. These organelles are involved in various reactions such as the breakdown of fatty acids, amino acids, and the detoxification of poisons like alcohol. In these processes, they produce hydrogen peroxide (H₂O₂), which is itself toxic; however, the peroxisomes contain enzymes that safely convert H₂O₂ into water and oxygen, thereby preventing cellular damage.