Double Fertilisation in Flowering Plants 🌸

Flowering plants pull off a clever two-for-one trick called double fertilisation. One visit from a pollen tube sparks both embryo and endosperm formation inside the same embryo sac. :contentReference[oaicite:0]{index=0}

Step-by-Step Story 🪄

  1. Pollen tube arrival
    It slips into a synergid and releases two haploid (n) male gametes. :contentReference[oaicite:1]{index=1}
  2. Syngamy — making the zygote 🍼
    One male gamete meets the haploid egg nucleus:
    \(n + n \;\rightarrow\; 2n\)
    The result is a diploid zygote, the future embryo. :contentReference[oaicite:2]{index=2}
  3. Triple fusion — making food for the baby 🍞
    The second male gamete joins the two haploid polar nuclei in the central cell:
    \(n + n + n \;\rightarrow\; 3n\)
    This forms the triploid Primary Endosperm Nucleus (PEN).
    Because three haploid nuclei fuse here, we call the event triple fusion. :contentReference[oaicite:3]{index=3}
  4. Why “double” fertilisation? 🎯
    Both syngamy and triple fusion occur in a single embryo sac, so botanists cheerfully dub the whole phenomenon double fertilisation. It’s a signature move seen only in flowering plants. :contentReference[oaicite:4]{index=4}
  5. Setting the stage for life 🌱
    The central cell with the new PEN becomes the Primary Endosperm Cell (PEC). It races ahead to build a nutrient-packed endosperm that will feed the embryo. Meanwhile, the zygote starts its journey toward becoming a mature embryo. :contentReference[oaicite:5]{index=5}

Flash Facts for Quick Revision ⚡

  • Double fertilisation couples embryo (\(2n\)) and endosperm (\(3n\)) formation in one go.
  • PEN = 3n; it launches endosperm development before the embryo starts growing.
  • Zygote = 2n; it gives rise to the embryo.
  • Both fusions happen inside one embryo sac—no extra visits needed!
  • This trick is unique to angiosperms, making it a favourite MCQ point.

High-Yield NEET Nuggets 🎯

  1. Definition and sequence of syngamy + triple fusion (double fertilisation).
  2. Ploidy levels: zygote (2n) vs PEN (3n).
  3. Role of Primary Endosperm Cell in nourishing the embryo.
  4. Uniqueness of double fertilisation to flowering plants.
  5. Order of post-fertilisation events: endosperm first, embryo second.

Keep these points on your fingertips, and you’ll breeze through questions on plant reproduction! 🌿✨