SSC MTS EXAM

Detailed explanation-1: -In over 60 per cent of angiosperms (mostly dicots ), pollen grains are shed at 2-celled stage. In the remaining species, the generative cell divide mitotically to give rise to the two male gametes before pollen grains are shed (3-celled stage).

Detailed explanation-2: -In about 70% of angiosperms, pollination occur at 3-celled stage. In about 40% of angiosperms, pollination occur at 2-celled stage. Generative cell divides meiotically to form two male gametes. In about 60% of the angiosperms, pollination occur when a pollen grain at least forms a vegetative cell and a generative cell.

Detailed explanation-3: -Pollen grains in more than 60% of angiosperms are shed at the two-celled stage but double fertilisation occurs in them. Double fertilization is the union of two male gametes and a female gametophyte. The process starts when a pollen grain clings to the stigma of the carpel, a flower’s female reproductive organ.