Q.
If sperms of moss and fern are put together near the archegonium of fern, only the sperms of fern find entry into archegonium. What is the reason for this?
The gametophytes of the ferns or Pteridophyta have independent existence. The phase is for a shorter duration as the predominant phase is sporophytic.
The meiospores germinate to form the gametophyte or the prothallus. They bear sex organs. In the case of homosporous ferns, the gametophyte is monoecious. On the other hand, for heterosporous ferns, the gametophytes are dioecious.
Antheridium and archaegonium are the male and female sex organs that produce male and female gametes. In most of the classes of the male gametes or the antherozoids are with more than two flagella or cilia and are generally spirally coiled. A single egg is present in the venter of the archaegonium.
On maturity, the archaegonium secretes a mucilaginous liquid that is rich in malic acid and water. The flagellated sperms swim in the liquid and come in contact with the egg.