Module: | Double Fertilization & Endosperm
Q71: Consider the following statements regarding pollen tube discharge and the formation of X-bodies:
1. Upon entering the targeted synergid, the tip of the pollen tube absorbs water from the synergid cytoplasm, swells, and ruptures to discharge its contents.
2. The degenerating nucleus of the penetrated synergid and the vegetative nucleus of the pollen tube condense to form two deeply staining structures known as X-bodies.
3. These X-bodies permanently encapsulate the two male gametes, acting as a secondary checkpoint to prevent them from reaching the egg cell.
Which of the above statements is/are correct?
2. The degenerating nucleus of the penetrated synergid and the vegetative nucleus of the pollen tube condense to form two deeply staining structures known as X-bodies.
3. These X-bodies permanently encapsulate the two male gametes, acting as a secondary checkpoint to prevent them from reaching the egg cell.
Which of the above statements is/are correct?
✅ Correct Answer: A
The correct option is A. Statements 1 and 2 are correct, but Statement 3 is strictly incorrect.
The final micro-mechanical event of pollen tube delivery is highly destructive.
Guided by the filiform apparatus, the tube enters one synergid.
Causally, the tube tip absorbs the synergid's fluid, creates immense osmotic pressure, and bursts open, releasing the two male gametes and the vegetative nucleus into the synergid's cytoplasm.
During this chaotic discharge, the nucleus of the destroyed synergid and the vegetative nucleus of the pollen tube undergo rapid degradation.
Under an electron microscope, these two degrading nuclear masses appear as dense, dark-staining artifacts traditionally termed "X-bodies." Statement 3 is factually reversed.
The X-bodies have no encapsulating or inhibitory function.
The two male gametes easily bypass these remnants; one exhibits amoeboid movement toward the egg cell for syngamy, and the other moves toward the central cell for triple fusion.
The final micro-mechanical event of pollen tube delivery is highly destructive.
Guided by the filiform apparatus, the tube enters one synergid.
Causally, the tube tip absorbs the synergid's fluid, creates immense osmotic pressure, and bursts open, releasing the two male gametes and the vegetative nucleus into the synergid's cytoplasm.
During this chaotic discharge, the nucleus of the destroyed synergid and the vegetative nucleus of the pollen tube undergo rapid degradation.
Under an electron microscope, these two degrading nuclear masses appear as dense, dark-staining artifacts traditionally termed "X-bodies." Statement 3 is factually reversed.
The X-bodies have no encapsulating or inhibitory function.
The two male gametes easily bypass these remnants; one exhibits amoeboid movement toward the egg cell for syngamy, and the other moves toward the central cell for triple fusion.