Question

Which of the following in female gametophyte of an angiosperm helps in guiding the pollen tube for fertilizing the eggs ?

• A. Polar nucleus
• B. Antipodals
• C. Synergids
• D. Central cells

Hint:

• The filiform apparatus is located at the micropylar end of the synergids.

• Once the pollen tube enters a synergid, the synergid degenerates, releasing the two male gametes to carry out double fertilization (one fuses with the egg cell, and the other fuses with the polar nuclei of the central cell).

Answer 1

The Correct Option is C

Step 1: Recall the embryo sac structure.
The mature female gametophyte of an angiosperm is a 7-celled, 8-nucleate embryo sac, with an egg apparatus, a central cell and antipodals.
Step 2: Identify the egg apparatus.
At the micropylar end sits the egg apparatus, made of one egg cell and two synergids on either side.
Step 3: Recall the filiform apparatus.
The synergids have special finger-like thickenings at their tips called the filiform apparatus.
Step 4: Trace the pollen tube path.
The pollen tube grows down the style and enters the ovule through the micropyle, then needs guidance to reach the egg.
Step 5: See who guides it.
The filiform apparatus of the synergids releases chemical (chemotropic) signals that guide the pollen tube into one of the synergids.
Step 6: Rule out the others and conclude.
Polar nuclei, antipodals and the central cell do not guide the tube. The synergids do, so they are the answer.
\[ \boxed{\text{Synergids}} \]