Question

In a mature fertilised ovule of angiosperms, the haploid (n), diploid (2n) and triploid (3n) structures, respectively are the

• A. synergids, endosperm and antipodals
• B. egg, secondary nucleus and embryo
• C. antipodals, embryo and zygote
• D. synergids, embryo and endosperm

Answer 1

The correct option is D synergids, embryo and endosperm


The embryo sac represents the female gametophyte in angiosperms and it is present inside the ovule. The embryo sac is formed from the haploid megaspore. Hence, all the cells inside the embryo sac are haploid. It is a 7 celled structure. Three antipodals, two synergids, one egg cell and one large central cell.

The zygote is formed by the fusion of two haploid gametes, hence it is diploid. The zygote develops into an embryo.

The endosperm is triploid as it is formed by the fusion of three haploid nuclei. Fusion of one male gamete (n) with the diploid secondary nucleus (2n) (formed by fusion of two haploid polar nuclei) results in the formation of triploid (3n) primary endosperm nucleus (PEN). PEN divides and develops into a triploid nutritive tissue, the endosperm.