# DBT JRF 2020 — Question 84

Exam: DBT JRF 2020 · Section: B · Topic: Plant Biology · Difficulty: Hard

## Question

In which organelle of seeds are stored oils converted to fatty acids and glycerol during germination?

## Options

- **A.** endoplasmic reticulum
- **B.** mitochondria
- **C.** glyoxysome
- **D.** amyloplast

## Answer

Option C

## Explanation

Glyoxysomes are specialised peroxisomes found in fatty seeds and seedling cotyledons. During germination, stored triacylglycerols are: (1) Hydrolysed to fatty acids + glycerol by lipases (in oil bodies/oleosomes); (2) Fatty acids transported to glyoxysome and activated to acyl-CoA; (3) $\beta$ -oxidation in glyoxysome: acyl-CoA → acetyl-CoA; (4) Glyoxylate cycle (unique to plants/fungi/bacteria, absent in animals): Isocitrate → succinate + glyoxylate (isocitrate lyase); glyoxylate + acetyl-CoA → malate (malate synthase). Net: 2 acetyl-CoA → 1 succinate; (5) Succinate exported to mitochondria → TCA → OAA → PEP → gluconeogenesis → sucrose for seedling growth. This allows plants to convert fat to carbohydrate — a pathway lacking in animals (no glyoxylate cycle).

Source: https://mypyqbuddy.com/questions/in-which-organelle-of-seeds-are-stored-oils-6a05a8a02adafec47029326c