Question

Meiosis occurs in ferns at the time of_______ formation
a. Spores
b. Gametes
c. Protonema
d. Prothallus

Answer 1

Hint: Ferns are leafy plants, this is first formed vascular plants that belong to Pteridophytes, and these plants have vascular tissue for the transport of nutrients and water, while the reproduction in the ferns is very different.

Complete answer:
- Ferns do not have flowers and seeds, where they reproduce by the spores.
- Ferns require water for sexual reproduction.
- In order to understand the reproduction of ferns better, one should understand the morphology of ferns.
- Ferns have leaf-like structures called fronds and these fronds have a leaflet like structure, which is called as pinna and the lower surface of this fronds have a spot like structures called spores, all leaves of the ferns having spores are called fertile fronds, all fronds are not fertile.
- The life cycle of the ferns has the alternation of generations, which means they require two types of plants to complete their life cycle.
- One is a diploid generation, which has two sets of chromosomes on their cells, that is the fronds having spores, called saprophytes which is diploid.
- From the saprophyte, haploid generation is produced by the spores, where the diploid undergo meiosis and form the haploid spores by meiosis.
- The haploid spores are formed under mitotic division to produce photosynthetic prothallus, which is also called a gametophyte.
- These gametophytes produce the gametes by mitosis, here meiotic division does not require because the gametophytes are already haploid.

Hence, the correct answer is option (A).

Note: The life cycle of the ferns are said to be sexual, though it reproduces through asexual methods, some times in dry conditions the sporophytes are directly converted to gametophyte without any fertilization.