A Prothallus isa)A structure in pteridophytes formed before the thallu...
Prothallus is a free-living, mostly photosynthetic thalloid gametophyte.
It is formed during the life cycle of Pteridophyte.
The pteridophyte is a sporophyte i.e. the main plant body is diploid
These spores formed inside the sporangia which are borne on the sporophylls.
The germination of spores is exosporic i.e. in the soil.
These spores germinate to form the gametophyte which is haploid.
The gametophyte formed is called prothallus and it is independent as the germination took place outside the sporophyte body in the soil.
Prothallus male and female sex organs are called antheridia and archegonia, respectively.
Water is required for the transfer of antherozoids – the male gametes released from the antheridia to the mouth of the archegonium.
Fusion of the male gamete with the egg present in the archegonium results in the formation of a zygote.
The zygote thereafter produces a multicellular well-differentiated sporophyte which is the dominant phase of the pteridophytes.
The sporophytic plant undergoes meiosis to form haploid spores.
Haploid spores divide by mitosis to form a haploid gametophyte once again.
So, the correct answer is
option 3, A gametophyte-free living structure formed in pteridophytes.
This question is part of UPSC exam. View all NEET courses
A Prothallus isa)A structure in pteridophytes formed before the thallu...
Prothallus in Pteridophytes
Understanding the Prothallus in Pteridophytes is crucial in comprehending the life cycle of these plants.
Explanation:
- What is a Prothallus?
- A prothallus is a gametophyte free-living structure formed in pteridophytes.
- It is a small, delicate, heart-shaped structure that is the gametophyte stage in the life cycle of ferns and other related plants.
- Formation of a Prothallus:
- The prothallus is formed from the spores released by the sporophyte.
- These spores germinate and develop into the prothallus, which is the haploid stage in the life cycle of pteridophytes.
- Function of a Prothallus:
- The prothallus is responsible for producing gametes, which are necessary for sexual reproduction in pteridophytes.
- It houses the reproductive structures where the sperm and egg cells are produced.
- Role in the Life Cycle:
- The prothallus is important in the alternation of generations characteristic of pteridophytes.
- It represents the gametophyte generation, while the sporophyte generation is represented by the fern plant that we typically see.
In conclusion, the prothallus is a vital part of the life cycle of pteridophytes as it is the structure where gametes are produced, leading to the formation of the sporophyte generation. Understanding the role and significance of the prothallus is essential in studying the reproductive biology of these fascinating plants.
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.