Plants that flower only once in their lifetime are called .....

Which plant flowers once every $12$ years?

Match the following columns:

Column-$I$ (Pre-fertilization)	Column-$II$ (Post-fertilization)
$P$. Ovule	$I$. Fruit
$Q$. Ovary	$II$. Seed
$R$. Integument	$III$. Seed coat
$S$. Ovary wall	$IV$. Pericarp

Indicate the stages where meiosis and mitosis occur $(1, 2$ or $3)$ in the flow chart: Megaspore mother cell $\xrightarrow{1}$ Megaspores $\xrightarrow{2}$ Embryo sac $\xrightarrow{3}$ Egg.

External fertilization is mostly observed in organisms that.....

What is the ratio of equational divisions that take place in Cycas and angiosperms respectively,leading to the formation of male gametes from pollen grains?