Question

State the function of the filiform apparatus found in a mature embryo sac.

Answer 1

Hint: A mature embryo sac is a seven celled and eight nucleated structure. Filiform apparatus are finger-like projections present in the cytoplasm on the micropylar end of the synergids. It helps in the process of syngamy.

Complete answer:
The filiform apparatus plays an important role, it guides the entry of pollen inside the synergid present at the micropylar end of the embryo sac.
The pollen tube is shown chemotaxis, filiform apparatus secretes chemicals that guide the pollen tube towards the embryo sac.
In flowering plants, after the pollen tube gets inside the synergids through the filiform apparatus, it bursts up and releases the content along with the two male gametes to the inside of the degenerating synergid which results into the fertilization forming a zygote.
The other male nuclei fertilize with the two polar nuclei leading to the formation of the primary endosperm nucleus, which gives rise to endosperm for providing nourishment to the developing embryo.

Note: Filiform apparatus is also responsible for the absorption of food from the nucellus into the embryo sac. The fusion of the first male gamete with the egg cell is termed as Syngamy. The fusion of the second male gamete with the two polar nuclei is termed as Triple fusion. Both syngamy and triple fusion are together called double fertilization.