The place where the sporangium of a fern bursts open is called:

During fertilization in ferns,the male gamete reaches the female gamete through the agency of:

Pteridophytes are called vascular cryptogams because they are non-seeded plants containing:

What is heterospory? Briefly comment on its significance. Give two examples.

How many of the following statements are true about $Azolla$?
$(a)$ It is free-floating.
$(b)$ It has bilobed leaves.
$(c)$ It is nitrogen-fixing.
$(d)$ It is a climber.
$(e)$ It has Aerenchyma in the ventral lobe of the leaf.

$Selaginella$ is heterosporous. It produces two types of spores. The microspore develops into microgametophyte and the megaspore develops into megagametophyte. With respect to gametophyte,which one statement is correct?