Arrange the following stages of the fern (pteridophyte) reproductive cycle in their correct chronological sequence, starting from spore germination:
- 1Germination of a haploid spore into a green cell filament
- 2Development of a heart-shaped photosynthetic prothallus bearing sex organs
- 3Transfer of flagellated sperm through water to fertilize the egg inside an archegonium
- 4Emergence and growth of a diploid leafy sporophyte from the prothallus
Answer
The correct chronological sequence is: Germination of a haploid spore into a green cell filament → Development of a heart-shaped photosynthetic prothallus bearing sex organs → Transfer of flagellated sperm through water to fertilize the egg inside an archegonium → Emergence and growth of a diploid leafy sporophyte from the prothallus.
In pteridophytes such as ferns, the life cycle exhibits alternation of generations where the haploid spore germinates first into a small, photosynthetic, heart-shaped prothallus (gametophyte). The prothallus produces gametes in sex organs (antheridia and archegonia). Swimming flagellated sperm require water to reach the egg cell inside the archegonium for fertilization. Once fertilized, the diploid zygote grows into the familiar leafy vascular plant, which is the dominant sporophyte generation.
Step-by-Step Solution
Key Concept
Fern Life Cycle and Alternation of Generations in Pteridophytes
Estimated Time:1m 0s