AP BIOLOGY

Detailed explanation-1: -double fertilization, in flowering plant reproduction, the fusion of the egg and sperm and the simultaneous fusion of a second sperm and two polar nuclei that ultimately results in the formation of the endosperm (the food-storage tissue) of the seed.

Detailed explanation-2: -Final answer: Endosperm of angiosperms forms after fertilization from the diploid nucleus.

Detailed explanation-3: -Double fertilization involves two sperm cells; one fertilizes the egg cell to form the zygote, while the other fuses with the two polar nuclei that form the endosperm.

Detailed explanation-4: -Final answer: The formation of endosperm takes place by the fusion of two polar nuclei and one male gamete.