Which are the three cells found in a pollen grain when it is shed at the three celled stage?
In over 60\% of angiosperms, pollen grains are shed at the two cell further stage (vegetative cell and generative cell). In the remaining species, the generative cell divides mitotically to give rise to the two male gametes before pollen grains are shed at the (three-celled stage (are vegetative cell and two male gametes).
$$ \text { What is self-incompatibility? } $$
It is a genetic mechanism which prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
$$ \text { Name the type of pollination in self-incompatible plants. } $$
In self-incompatible plants, (while self-pollination is incompatible) cross-pollination is occurs.
Draw the diagram of a mature embryo sac and show its eight-nucleate, seven-celled nature. Show the following parts-antipodals, synergids, egg, central cell, polar nuclei.
$$ \text { A mature embryo sac (seven celled with eight nucleated structure) } $$
Which is the triploid tissue in a fertilised ovule? How is the triploid condition achieved?
Fertilised embryo sac showing Primary endosperm nucleus ( $3 n$ )