NEET 2020 Botany Question 12 Solution

In angiosperms, the dominant conspicuous plant body is the diploid sporophyte ($2n$). The haploid gametophyte ($n$) is extremely reduced, non-photosynthetic, and parasitic, developing entirely within sporophytic parental tissues: - (a) Pollen grains inside the anther: The stamen and anther walls (epidermis, endothecium, middle layers, tapetum) are parental sporophytic tissues ($2n$). The pollen grain represents the immature male gametophyte ($n$) developing within the microsporangium. This represents generation $n$ nested directly inside generation $2n$. - (d) Embryo sac inside the ovule: The ovule (megasporangium with funicle, integuments, and nucellus) is parental sporophytic tissue ($2n$). Within the nucellus sits the 7-celled, 8-nucleate female gametophyte / embryo sac ($n$). This is another classic example of generation $n$ nested directly inside generation $2n$.

- (b) Germinated pollen grain with two male gametes: Both the pollen tube/vegetative cell ($n$) and the generative-derived sperm cells ($n$) belong to the exact same haploid gametophytic generation ($n$). - (c) Seed inside the fruit: The seed represents the next sporophytic generation ($2n$ embryo) along with endosperm ($3n$) inside the maternal ovary fruit wall ($2n$).