What defines the role of the endosperm in seeds?

The endosperm is a critical tissue within seeds, primarily serving the purpose of providing nourishment to the developing embryo. This specialized tissue is a product of double fertilization in flowering plants, where one sperm cell fertilizes the egg cell, forming the zygote, while the other sperm cell fuses with two polar nuclei to create the endosperm. As the embryo begins to grow, it relies on the stored nutrients in the endosperm for energy and sustenance.

This storage typically includes starches, proteins, and oils, which are essential for the early stages of the plant's life before it develops the capability to photosynthesize or absorb nutrients from the soil. Because seedlings depend on the endosperm for their initial growth and development, its role is vital for the successful establishment of the plant.

The other roles mentioned in the incorrect responses do not accurately describe the endosperm; it does not store genetic material or hold the embryo, as those functions are associated with the seed coat and the zygote, respectively. The endosperm's primary role is focused entirely on nourishment, making it essential for the plant's growth following germination.