Describe the post-fertilization changes in a flower.
Solution: In angiosperms, double fertilization takes place; one male gamete fuses with the egg cell to form the zygote and another male gamete fuses with the polar nuclei to form the endosperm. Various changes take place after fertilization. These include endosperm and embryo development, maturation of the ovules to form seeds and maturation of the ovary to give rise to a fruit. The zygote divides to give rise to two cells called as the terminal cell and basal cell. The basal cell divides to form the suspensor which is a linear group of cells. The terminal cell divides to form the embryo. These embryo cells are further divided to form the different stages in the development phase. The first stage is the globular stage, followed by heart stage and finally the torpedo stage. This embryo develops and matures inside the seed.