Q.Define double fertilizations found in angiosperms. Point out its significance.
You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
Start your 14-day free trial to unlock the full solution →Double fertilization is the fusion of the two male gametes delivered by the pollen tube with the egg cell and the polar nuclei of the embryo sac, forming a zygote and a triploid endosperm respectively — it is unique to flowering plants.
Double fertilization
In angiosperms, the pollen tube grows through the style and enters the ovule (usually through the micropyle), carrying two non-motile male gametes. On reaching the embryo sac, the pollen tube releases both male gametes into the cytoplasm of the synergid, where two independent fusion events take place — together termed double fertilization (the term was coined by S.G. Nawaschin in 1898):
- Syngamy: One male gamete (n) fuses with the egg cell/oosphere (n) to form the diploid (2n) zygote.
- Triple fusion: The second male gamete (n) fuses with the two polar nuclei (or the secondary/central nucleus formed by their fusion) located in the central cell, producing the triploid (3n) primary endosperm nucleus (PEN).
Because both a syngamy event and a triple-fusion event occur together in the same embryo sac, the overall process is called double fertilization, and it is a defining, unique feature of angiosperm reproduction.
Significance of double fertilization
- The zygote (from syngamy) develops into the embryo — the next sporophytic generation — ensuring genetic recombination and continuity of the species.
- The PEN (from triple fusion) develops into the endosperm, a nutritive tissue that nourishes the developing embryo (either consumed by the embryo before seed maturity, as in non-endospermous seeds like pea and gram, or retained in the mature seed, as in endospermous seeds like maize and castor). …
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.