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Through which cell of the embryo sac does the pollen tube enter the embryo sac -
A
Persistent synergid
B
Egg cell
C
Central cell
D
Degenerated synergid
Detailed Solution
The egg apparatus at the micropylar end of the embryo sac consists of the egg cell and two synergids, which have a filiform apparatus at their micropylar tips.
Before or at the time of arrival of the pollen tube, one of the two synergids degenerates.
The pollen tube, guided by the filiform apparatus, enters the embryo sac through this degenerated synergid and discharges the two male gametes into its cytoplasm.
One male gamete then fuses with the egg (syngamy) and the other with the two polar nuclei of the central cell (triple fusion).
The other synergid persists for some time and degenerates later.
So the pollen tube enters the embryo sac through the degenerated synergid.
Before or at the time of arrival of the pollen tube, one of the two synergids degenerates.
The pollen tube, guided by the filiform apparatus, enters the embryo sac through this degenerated synergid and discharges the two male gametes into its cytoplasm.
One male gamete then fuses with the egg (syngamy) and the other with the two polar nuclei of the central cell (triple fusion).
The other synergid persists for some time and degenerates later.
So the pollen tube enters the embryo sac through the degenerated synergid.