(A) Glyoxysome
(B) Lysosome
(C) Peroxisome
(D) Dictyosome
Hydrogen peroxide (H2O2) forms during photorespiration in plant cells under high light and low CO2. This SEO article explains Q.49 with the correct answer and all options for biology exams.
Correct Answer
The correct answer is (C) Peroxisome.
In photorespiration, glycolate oxidase in peroxisomes oxidizes glycolate to glyoxylate, directly producing H2O2 as a byproduct. Catalase in peroxisomes then detoxifies this reactive oxygen species to prevent cellular damage.
Option Breakdowns
(A) Glyoxysome
Glyoxysomes specialize in fatty acid breakdown to sugars in germinating seeds via the glyoxylate cycle.
They handle glyoxylate but not photorespiratory H2O2 production, which occurs in leaf peroxisomes.
(B) Lysosome
Lysosomes degrade macromolecules via hydrolysis in animals, absent or rare in plant cells.
No role in plant photorespiration or H2O2 generation; irrelevant to this process.
(C) Peroxisome
Peroxisomes host photorespiratory reactions where glycolate oxidase generates H2O2 from glycolate.
This organelle’s catalase neutralizes H2O2, linking it directly to the pathway in C3 plants.
(D) Dictyosome
Dictyosomes (Golgi apparatus) modify, sort, and package proteins and lipids.
They lack enzymes for photorespiration and do not produce H2O2 in this context.
| Option | Organelle Function | Photorespiration H2O2 Role | Matches Q.49? |
|---|---|---|---|
| (A) Glyoxysome | Glyoxylate cycle in seeds | None | No |
| (B) Lysosome | Degradation (animal) | None | No |
| (C) Peroxisome | Glycolate oxidation | Produces H2O2 | Yes |
| (D) Dictyosome | Protein packaging | None | No |
