Question 95 of 99
Q.The correct order of haploid, diploid and triploid structure in fertilized embryo sac is :
(a) Antipodal, Synergid and PEN
(b) Synergid, Zygote and PEN
(c) Synergid, Polar nuclei and Zygote
(d) Synergid, Antipodal and Polar nuclei
Puducherry TnboardTamil Nadu HSC (DGE) Board 2026MCQ· 1mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →The correct haploid, diploid, triploid sequence in the fertilised embryo sac is Synergid (n), Zygote (2n), and PEN (3n).
Working
In a mature angiosperm embryo sac (typically the Polygonum-type, 7-celled/8-nucleate), the structures present, before and after double fertilisation, have different ploidy levels:
- Synergids (2 of them, forming the egg apparatus along with the egg cell) remain haploid (n) throughout -- they are never fertilised and eventually degenerate after pollen tube entry.
- Antipodal cells (3, at the chalazal end) are also haploid (n) and are not involved in fertilisation.
- Egg cell, on fusion with one male gamete (n + n), becomes the zygote, which is diploid (2n).
- Polar nuclei (2, in the central cell) are each individually haploid (n); when they fuse with each other they form the diploid secondary nucleus, and when this secondary nucleus then fuses with the second male gamete (n) during double fertilisation, it forms the Primary Endosperm Nucleus (PEN), which is triploid (3n). …
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