Which cell organelle is defined as the small round organelle that undergoes oxidation reaction to produce hydrogen peroxide?

Correct — D. Peroxisomes are the small, round, single-membrane organelles whose oxidase enzymes strip hydrogen from a substrate and pass it to oxygen, producing hydrogen peroxide (H₂O₂).

The organelle is named for that product. It also carries catalase, which breaks the peroxide straight down into water and oxygen, so the cell is not poisoned by what it makes.

Peroxisomes also break down long-chain fatty acids, and in germinating seeds the related glyoxysomes turn stored fat into sugar.

Why the others are wrong

• (a)
  Vacuole — The vacuole is a storage sac for water, ions, food and waste, bounded by the tonoplast. Storage is not oxidation, and it produces no hydrogen peroxide.
• (b)
  Nucleus — The nucleus holds the DNA and controls the cell's activity. It is the site of transcription, not of an oxidase reaction.
• (c)
  Centrosome — The centrosome organises microtubules and forms the spindle during cell division in animal cells. Its role is mechanical, not metabolic.

Cell biology in SSC papers is a function table: the stem gives a function and asks for the organelle, or gives a mismatched pair and asks you to spot it.

Two enzyme-carrying bodies are routinely confused. Lysosomes digest — they hold hydrolytic enzymes and work in an acidic interior. Peroxisomes oxidise — they hold oxidases and catalase.

Hydrogen peroxide is the hinge. It is a reactive by-product, dangerous inside a cell, and the peroxisome both makes it and destroys it in the same compartment.

Key facts

• Peroxisomes carry out oxidation reactions that produce hydrogen peroxide.
• Catalase in the peroxisome breaks hydrogen peroxide down into water and oxygen.
• Lysosomes digest with hydrolytic enzymes while peroxisomes oxidise.
• Glyoxysomes are the fat-converting peroxisome-like bodies of germinating seeds.

Common traps

• Marking the nucleus because the stem says small and round.
• Forgetting that the peroxisome both produces hydrogen peroxide and destroys it.

No directly related past PYQ was found.