Question

Function of guiding and attracting pollen tube is done by
A. Egg cell
B. Filiform apparatus
C. Antipodal cells
D. Secondary nucleus

Answer 1

Hint: The ovule is an integument megasporangium within which the meiosis and megaspore formation takes place. It develops into a seed after fertilization. Each ovule usually consists of a nucellus investor by one or two integuments and a stalk by which it is attached to the placenta of the ovary. The various parts of the ovule are funiculus, hilum, raphe, nucellus, embryo sac, integuments, micropyle, and chalaza.

Complete step by step answer: A fully developed typical or polygonum type of embryo sac (female gametophyte or megagametophyte) is a large and oval structure consists of seven cells
Single egg or oosphere. It is polar in an organization in which the cytoplasmic elements are arranged towards the chalazal end and vacuolated cytoplasm towards the micropylar end. The wall of the egg is common with synergids. After fertilization, the egg develops its own cell wall and becomes a zygote. Two synergids are elongated cells that bear the filiform apparatus in the micropylar region. The cell wall is incomplete i.e., two-third portion of the cells towards the chalazal end is without a cell wall. The filiform apparatus helps in the absorption and transportation of nutrients into the embryo sac. They direct the pollen tube growth by secreting some chemical substances and function as a shock absorbed during the penetration of the pollen tube into the embryo sac. Sometimes they project out to form synergid haustoria. Three antipodal cells are vegetative cells of the embryo sac. They degenerate before and after fertilization or help in the absorption of nutrients. A single large central cell contains two polar nuclei which fuse to form a diploid secondary nucleus. During fertilization, one male gamete fuses with the secondary nucleus to form a triploid nucleus. After fertilization, the central cell develops endosperm(3n).
So the correct answer is option B, i.e., Filiform apparatus

Note: Out of the four nuclei at the micropylar pole, three differentiate to produce egg apparatus consisting of an egg and two synergids. Similarly, at the chalazal end, three of four nuclei differentiate as antipodal cells. The two remaining nuclei termed polar nuclei migrate towards the center. They meet at the center and may remain separate until the discharge of male gametes or fuse to form a diploid secondary nucleus of the central cell.