When the pollen tube enters the ovule through the micropyle,it is termed as:

Pollen grains can be stored for years in ........

In pollen grains released at the $2$-celled stage,where are the male gametes formed?

Which structure guides the entry of the pollen tube into the synergids?

In angiosperms,the pollen tube enters the embryo sac through:

In wheat and rice,pollen grains lose viability within $30$ minutes of their release. In members of the families Rosaceae,Leguminosae,and Solanaceae,the viability is maintained for $...$.