Question

What will be the number of chromosomes in prothallus, antheridium, antherozoids, spores, if the cell of the archegonium of a fern plant has 20 chromosomes?

• A. 20, 20, 20, 20
• B. 40, 40, 40, 40
• C. 20, 20, 40, 40
• D. 40, 40, 20, 20

Answer 1

The correct option is A 20, 20, 20, 20

The gametophyte of pteridophytes is called prothallus.
Haploid spores germinate to form gametophytes in pteridophytes. Hence gametophyte is haploid.
Male gametophyte bears male sex organs, antheridium and female gametophyte bears female sex organs, archegonium. Sex organs are haploid and hence produce gametes by mitosis. Male gametes are called antherozoids and they are haploid.

Prothallus, antheridium, archegonium, antherozoids and spores are haploid structures. Hence, all of these will have 20 chromosomes.