Fusion of a male gamete with the secondary buicleus forms the

$A$ : In sporoderm, pectocellulosic layer is surrounded by sporopollenin.
$R$ : Exine is differentiated into outer ektexine and inner endexine.

Give scientific reasons : The flower possesses religious, cultural and scientific value.

The arrangement of the nuclei in a normal embryo sac in the dicot plants is

Non-viable seeds are produced by