BOTANY

Detailed explanation-1: -Pollen tube (PT) serves as a vehicle that delivers male gametes (sperm cells) to a female gametophyte during double fertilization, which eventually leads to the seed formation.

Detailed explanation-2: -Once the pollen tube reaches its destination, it discharges the two sperm cells into the embryo sac and double fertilization takes place. One of the sperm cells fuses with the egg cell (this will develop into the embryo); the other will fuse with the central cell to make the endosperm (Figure 1B).

Detailed explanation-3: -Synergids, the cells that are part of the egg apparatus along with the egg cell. The pollen germinates on the stigma to form the pollen tube.

Detailed explanation-4: -They act as conduits to transport the male gamete cells from the pollen grain or from the stigma (in flowering plants) to the ovules at the base of the pistil.