AP BIOLOGY

Detailed explanation-1: -After the pollen grain lands on the stigma, a pollen tube develops down through the style to the ovary. The pollen grain travels along the pollen tube and fertilizes the nucleus in the ovule. The fertilized ovule develops into a seed.

Detailed explanation-2: -After pollen lands on the stigma, it initiates pollen tube formation. Pollen tubes are channels which grow down the length of the style to the ovules. After a pollen grain travels down a pollen tube it intercepts an ovule, fertilizes the female germ cells and initiates seed development.

Detailed explanation-3: -1 Pollen grains land on the stigma and begin to grow pollen tubes. Sperm cells within the pollen grain move down the pollen tube and into an ovule.

Detailed explanation-4: -Cross-pollination is a type of pollination in which the transfer of pollen from the anther of one flower to the stigma of another flower on a different plant of the same species.

Detailed explanation-5: -When pollen gran falls on stigma, it germinates on stigma and produce pollen tube which enters into the ovule release 2 male gametes and fuse with the ovule to form a seed.