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In germinating seeds fatty acids are degraded exclusively in the:
A
peroxisomes
B
mitochondria
C
proplastids
D
glyoxysomes
Detailed Solution
Glyoxysomes are single membrane-bound microbodies found in the fat-storing tissues (endosperm or cotyledons) of germinating oil seeds such as castor and groundnut.
They contain the enzymes for the $\beta$-oxidation of fatty acids and the enzymes of the glyoxylate cycle (isocitrate lyase and malate synthase).
In them the stored fatty acids are broken down to acetyl CoA, which is converted through the glyoxylate cycle into succinate and finally into sugars (gluconeogenesis) for the growing seedling.
So in germinating seeds the degradation of fatty acids takes place exclusively in the glyoxysomes.
Peroxisomes of leaves are concerned mainly with photorespiration, mitochondria carry out the Krebs cycle and oxidative phosphorylation, and proplastids are immature plastids.
Hence the answer is glyoxysomes.
They contain the enzymes for the $\beta$-oxidation of fatty acids and the enzymes of the glyoxylate cycle (isocitrate lyase and malate synthase).
In them the stored fatty acids are broken down to acetyl CoA, which is converted through the glyoxylate cycle into succinate and finally into sugars (gluconeogenesis) for the growing seedling.
So in germinating seeds the degradation of fatty acids takes place exclusively in the glyoxysomes.
Peroxisomes of leaves are concerned mainly with photorespiration, mitochondria carry out the Krebs cycle and oxidative phosphorylation, and proplastids are immature plastids.
Hence the answer is glyoxysomes.