Q.Describe the post-fertilisation changes in a flower.

Fertilisation in a flowering plant triggers a series of developmental changes that transform the flower into a fruit bearing seeds:

• Zygote formation and embryo development: The fusion of the haploid male gamete with the haploid egg cell (syngamy) forms the diploid zygote, which undergoes repeated mitotic divisions and differentiation to become the embryo of the new plant.
• Endosperm formation: In flowering plants, a second fusion event (triple fusion) — of a male gamete with the two polar nuclei — produces the primary endosperm nucleus, which develops into the endosperm, a nutritive tissue that nourishes the developing embryo (either consumed by the embryo during seed development, as in non-endospermic seeds, or persisting in the mature seed, as in endospermic seeds).
• Ovule develops into seed: The whole ovule, containing the developing embryo and endosperm, develops into the seed. The outer protective layers of the ovule, the integuments, become the hardened, protective seed coat (testa and tegmen).
• Ovary develops into fruit: The ovary wall develops into the pericarp, the wall of the fruit, which encloses the seed(s) and may be dry or fleshy depending on the species, aiding in protection and/or dispersal of the seeds. …

Trace each fertilisation product to its mature structure: zygote → embryo; triple fusion product → endosperm; ovule (with integuments) → seed (seed coat); ovary (wall) → fruit (pericarp); then note th …

• Omitting endosperm formation (triple fusion) — a commonly missed step distinct from zygote/embryo formation.
• Not specifying WHICH part becomes WHAT (e.g., saying 'ovule becomes seed' without noting integuments become the seed coat, or 'ovary becomes fruit' without noting the wall becomes the pericarp). …