In angiosperm, the haploid, diploid and triploid structures of a fertilized embryo sac sequentially are [2023]
Synergids, zygote and primary endosperm nucleus
Synergids, antipodals and polar nuclei
Synergids, primary endosperm nucleus and zygote
Antipodals, synergids, and primary endosperm nucleus.
(1)
Synergids and antipodals are haploid structures. Zygote and polar nuclei are diploid structures. Primary endosperm nucleus is triploid structure of a fertilised embryo sac. In a fertilised embryo sac the haploid, diploid and triploid structures are synergids, zygote and primary endosperm nucleus, respectively.
What is the fate of the male gametes discharged in the synergid? [2019]
One fuses with the egg and other fuses with central cell nuclei.
One fuses with the egg, other(s) degenerates in the synergid.
All fuse with the egg.
One fuses with the egg, other(s) fuse(s) with synergid nucleus.
(1)
During double fertilisation in angiosperms, one male gamete fuses with the egg to form the diploid zygote (syngamy or generative fertilisation). The diploid zygote finally develops into embryo. The other male gamete fuses with the two polar nuclei (or secondary nucleus) to form the triploid primary endosperm nucleus, PEN (triple fusion or vegetative fertilisation).
Double fertilisation is [2018]
fusion of two male gametes of a pollen tube with two different eggs
fusion of one male gamete with two polar nuclei
fusion of two male gametes with one egg
syngamy and triple fusion
(4)
Double fertilisation is unique and universal feature of angiosperms. Total number of nuclei involved in double fertilisation is five, i.e., 2 in syngamy and 3 in triple fusion. Syngamy is fusion of one male gamete with egg to form zygote. Triple fusion occurs when the second male gamete fuses with 2 polar nuclei or secondary nucleus to form triploid primary endosperm nucleus.
Double fertilisation is exhibited by [2017]
algae
fungi
angiosperms
gymnosperms
