Question

The filiform apparatus is located at the
A. Tip of microsporangium
B. Tip of the filament
C. Tip of megasporangium
D. Pericarp

Answer 1

Filiform apparatus is formed from synergid cells. For pollen tube guidance in ovules, synergid cells are important. They play a prominent role during fertilization since they represent the primary channel between male gametophytes and female gametophytes.

Complete answer: At the micropylar end of the embryo sac, the synergid cell wall forms a strongly thickened structure called the filiform apparatus. It consists of several finger-like projections into the synergid cytoplasm. The purpose of the filiform apparatus is to help guide the pollen tubes in the synergies. Generative cells are a type of seed plant male gametophyte (pollen grain) cell that divides and gives rise to two mature sperms. In nature, nucellar at embryos are apomictic diploids. Nucellar embryo initial cells were histologically evident in flowers' ovules just before anthesis. Thus, we can say that a highly thickened structure called the filiform apparatus at the micropylar end is created by the synergid cell wall, consisting of multiple finger-like projections into the synergid cytoplasm. The purpose of the filiform apparatus is to lead the embryo to the pollen tubes. It's on the tip of the megasporangium or the sac embryo.
So, Option A-'Tip of Megasporangium' is the right answer.

Note: From one functional megaspore, the female gametophyte (embryo sac) forms. In order to form eight nucleate embryo sacs, this megaspore undergoes three mitotic divisions. The first mitotic division in the megaspore produces two nuclei where one nucleus moves towards the micropylar end and the other nucleus moves towards the chalazal end. These nuclei then divide at their respective ends and obtain division to form eight phases called nucleate phases. Consequently, at both ends, i.e. at the micropylar and chalazal end in the embryo sac, there are four nuclei each.