Question

Which of the following has a filiform apparatus as characteristic feature?
A) Synergids
B) Generative cell
C) Nucellar embryo
D) Aleurone cell

Answer 1

Hint:Synergid cells are necessary for pollen tube guidance in ovule.The perform a prominent role during fertilization because they represent the primary channel between male gametophytes and female gametophytes.

Complete Answer:
1) The synergid cell wall forms a highly thickened structure called the filiform apparatus at the micropylar end.It consists of numerous finger-like projections which are into the synergid cytoplasm. The function of the filiform apparatus is that it helps in leading the pollen tubes in the synergids.
2) Generative cell is a type of the male gametophyte (pollen grain) cell of seed plants which divides and gives rise directly or indirectly to sperm.
3) Nucellar embryos are apomictic diploids in nature.Nucellar embryo initial cells were evident histologically in ovules of flowers just prior to anthesis.

Additional information:The female gametophyte (embryo sac) develops from a single functional megaspore. This megaspore undergoes 3 mitotic divisions to form eight nucleate embryo sacs.
The first mitotic division in the megaspore forms two nuclei where one nucleus moves towards the micropylar end and the other nucleus moves towards the chalazal end. After that, these nuclei divide at their respective ends and gain divide to form eight stages called as nucleate stages. As a result, there are four nuclei each at both the ends i.e., at the micropylar and the chalazal end in the embryo sac. At the end of the micropylar, out of the four nuclei, only three nuclei differentiate into two synergids and one to the egg cell. All Together they are known as the egg apparatus.

Hence, the correct answer is option A (Synergids).

Note:Animals that perform metamorphosis are said to have indirect development. In earthworm development is direct which means no larval stage and hence no metamorphosis.