Question

Development of an embryo sac from a nucellar cell is
(A) Diplospory
(B) Apospory
(C) Apogamy
(D) Adventitive embryony

Answer 1

The development of a diploid embryo sac from a nucellar cell of ovule happens through mitosis .

Complete step by step answer:
Diplospory is a type of agamospermy, process of clonal reproduction through the seeds, in which the complete megaspore mother cell (MMC)experiences mitosis rather than meiosis and give rise to a developed embryo sac. Diplospory is considered as a process where the female gametophyte gets developed a sporangium. Apospory is also a type of agamospermy in which the nucellar cells present in the ovule undergo mitotic division and form a complete diploid embryo sac. Apospory is the formation of gametophytes from respective sporophytes devoid of development of spores. Apogamy is a process of development of sporophytes from gametophytes deprived of the union of gametes. Adventive embryony is a type of apomixis, an asexual reproduction which takes placedevoid of fertilization and not including meiosis, in which development of embryo occurs because of sporophytic budding.
In adventive polyembryony there is formation of extra embryos due to sporophytic budding. Apogamy is the development of sporophyte from the gametophyte without the fusion of gametes. Apomixis is a through which the sexual reproduction in the plants is replaced by asexual reproduction in the unfavorablesituations.

So, option (B) is the correct answer.

Note:
Adventive embryony is also referred as sporophytic budding, sporophytic apomixis or nucellar embryony. In the case of plants, polyembryony is the process in which more than one embryo occurs in a single seed, whereas in the case of humans, the polyembryony is a process where two or more embryos are developed from a single fertilized egg. In general this is also referred as identical twins.