Read the following statements and choose the incorrect statements for pollen grain:

(i) The vegetative cell is bigger, has abundant food reserve and a large irregularly shaped nucleus.

(ii) The generative cell is small and floats in the cytoplasm of the vegetative cell.

(iii) In over 60 per cent of angiosperms, pollen grains are shed at 3-celled stage.

(iv) The period for which pollen grains remain viable is highly variable and to some extent depends on the prevailing temperature and humidity.

(v) In some cereals such as rice and wheat, pollen grains maintain viability for months.

(vi) In some members of Rosasceae, Leguminosae and Solanaceae, pollen grains lose viability within 30 minutes of their release.

(vii) It is not possible to store pollen grains of a large number of species for years in liquid nitrogen (-196 O C).