i) Define pollination. ii) Explain double fertilisation. iii) Draw a labelled diagram of structure of fertilised embryo sac.

**OR**

i) Define Xenogamy pollination. ii) Write one example of each non-albuminous, albuminous, perispermic seed. iii) Draw a labelled diagram of L.S. o

Question

i) Define pollination. ii) Explain double fertilisation. iii) Draw a labelled diagram of structure of fertilised embryo sac.

**OR**

i) Define Xenogamy pollination. ii) Write one example of each non-albuminous, albuminous, perispermic seed. iii) Draw a labelled diagram of L.S. of pistil showing path of pollen tube growth.

Accepted Answer

![Figure — Part iii asks for a labelled diagram of the fertilised embryo sac; the canonical 'Fertilised embryo sac showin](/figures/sexual-reproduction-in-flowering-plants/fertilised-embryo-sac-zygote-primary-endosperm-nucleus-fig-1-13.svg)

>

> [!TLDR]
> Pollination transfers pollen to the stigma; double fertilisation (syngamy + triple fusion) is unique to flowering plants and produces both the zygote and the primary endosperm nucleus within the embryo sac.
>
> **i) Pollination:** Pollination is defined as the transfer of pollen grains from the anther (male part) to the stigma (receptive part of the female pistil) of a flower. Depending on the source of pollen, it may be autogamy (same flower), geitonogamy (different flower, same plant) or xenogamy (different plant of the same species).
>
> **ii) Double fertilisation:** After pollen germinates on the stigma, the pollen tube grows through the style and enters the ovule (usually through the micropyle), releasing two male gametes into the cytoplasm of the synergid. Inside the embryo sac (which has 7 cells and 8 nuclei: one egg cell, two synergids, three antipodal cells, and one central cell with two polar nuclei):
> 1. One male gamete fuses with the egg cell (syngamy), forming the diploid zygote.
> 2. The other male gamete fuses with the two polar nuclei of the central cell (triple fusion), forming the triploid Primary Endosperm Nucleus (PEN).
>
> Since two distinct fusion events take place involving the two male gametes, the process is termed double fertilisation - a unique feature of flowering plants, first discovered by Nawaschin (1898).
>
> **iii) Structure of the fertilised embryo sac (described, as text cannot show a hand-drawn figure):** …

Q.i) Define pollination. ii) Explain double fertilisation. iii) Draw a labelled diagram of structure of fertilised embryo sac. OR

Concept understanding — Triple Fusion Process

Triple Fusion Process – A First Look

What Triple Fusion Actually Means

Why Does Triple Fusion Matter?

What the NCERT Textbook Says

A Simple Way to Remember

Q.i) Define pollination. ii) Explain double fertilisation. iii) Draw a labelled diagram of structure of fertilised embryo sac. OR

🎓Unlock everything free for 14 days

Unlock everything free for 14 days