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Describe the post-fertilization changes in a flower.

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Hint:Fertilization occurs when one of the sperm cells fuses with the egg inside of an ovule. After fertilization each ovule develops into a seed series of events that takes place after fertilization to develop a seed from an ovule and fruit from the ovary.

Complete answer:
 Development of an endosperm and embryo, maturation of ovules into seeds and ovary into fruits takes place after fertilization.
1. Endosperm development precedes embryo development. The primary endosperm cell divides repeatedly to form a triploid endosperm tissue.
2. Embryo develops at the micropylar ends of the embryo sac where the zygote is situated. Zygotes divide only when a certain amount of endosperm is formed. The nutrition for development is provided by endosperm. The zygote gives rise to pro embryo, the globular, heart shaped and natural embryo. Dicot embryo consists of an embryonic axis and two cotyledons and monocots possess only one cotyledon at one end; this cotyledon is called scutellum.
3. Development of a seed-double fertilization in angiosperms triggers the transformation of ovule into a seed. Seeds are formed inside the fruits. A typical seed consists of a seed coat, cotyledon and an embryo axis.
4. Fruit formation – Fruit is formed as a result of cell division and differentiation in the ovary, which is transformed into fruit as a result of stimuli received from pollination as well as developing seed. The wall of ovary develops into a wall of fruit called pericarp which may be fleshy or leathery (guava, cucumber, tomato etc.) and dry (pea, bean, mustard). Pericarp protects the seed and helps in seed dispersal.

Note:Various changes take place after fertilization. It helps to restore the number of chromosomes and zygote develops to form new individuals which is necessary for the continuation of the species. It creates genetic variation.