Peroxisomes are membrane-bound organelles with many enzymes that primarily ...

• A. Break down fatty acids and other organic compounds
• B. Store calcium ions
• C. Synthesize ribosomes
• D. Generate hydrogen gas

Answer: (A)

Peroxisomes specialize in breaking down fatty acids and certain other organic compounds. They house enzymes that perform beta-oxidation, especially for very long-chain fatty acids, producing acetyl-CoA that can feed into metabolism. They also contain catalase to detoxify reactive hydrogen peroxide by converting it to water and oxygen, helping protect the cell from oxidative damage. This combination of fatty acid catabolism and detoxification is the primary function of peroxisomes, which is why describing them as breaking down fatty acids and other organic compounds fits best. They do not serve as storage sites for calcium ions (that role is mainly with the endoplasmic/sarcoplasmic reticulum and other storage sites), nor do they synthesize ribosomes (ribosome production occurs in the nucleolus and cytoplasm). They also do not generate hydrogen gas as a normal function; the relevant byproduct is hydrogen peroxide, which is neutralized inside the organelle.