In which organelle of seeds are stored oils converted to fatty acids and glycerol during germination?
1. endoplasmic reticulum
2. amyloplast
3. mitochondria
4. glyoxysome

Detailed Explanation:

The correct answer is: 4. Glyoxysome

What Are Glyoxysomes?

Glyoxysomes are specialized peroxisomes found primarily in the fat-storing tissues of germinating seeds—especially in plants like castor, sunflower, and soybean. They are crucial for converting stored lipids (oils) into usable energy during the early stages of germination, before the seedling can perform photosynthesis.

The Role of Glyoxysomes in Oil Conversion:

During seed germination, stored triglycerides in oil bodies are broken down into:

• Fatty acids

• Glycerol

These are further metabolized through:

• β-oxidation of fatty acids, which occurs in glyoxysomes, resulting in acetyl-CoA.

• The glyoxylate cycle, which operates in glyoxysomes, bypasses the decarboxylation steps of the citric acid cycle to conserve carbon and convert acetyl-CoA into succinate.

• Succinate is transported to mitochondria and used to generate energy and biosynthetic precursors.

Why Not Other Organelles?

• Endoplasmic Reticulum is involved in protein and lipid synthesis but not lipid breakdown.

• Amyloplasts are responsible for starch storage and are unrelated to lipid metabolism.

• Mitochondria are involved in respiration but do not carry out the initial steps of lipid breakdown.

Summary:

Glyoxysomes play a pivotal role in the mobilization of stored lipids in seeds by converting oils into fatty acids and glycerol during germination, supporting the seedling’s growth before photosynthesis kicks in.