Question

51 Review questions: 1. Does the thallus contain vascular tisues? 2. 1s the thallus the gametophyte or the sporophyte generation? 3. Where are the rhizoids located and what is their function? 4. Where is the pore located and what is its function? (similar to stoma in higher plants) 5. Is the gemmae cup a sexual or asexual reproductive structure? 6. Are gemmae haploid or diploid?_ 7. When rain splashes the gemmae out of the cup, what do they grow into? 8. Are archegonia and anthenda sexual or asexual reproductive structures 9. Are the gametes (eggs and sperm) of these plants formed by mitosis or meiosis? 10. Following fertilization to form a zygote, what does the embryo become? 11. Is the sporophyte haploid or diploid? 12. Do the spore mother cells form spores by mitosis or meiosis? 13. Are the released spores haploid or diploid? 14. What does a released spore become? 15. Why are liverworts, like most bryophytes, restricted to moist habitats, and why are they always small?

Answer 1

Q1) The thallus of liverwort does not contain vascular tissues.

These are non-vascular plants, they do not have a vascular system having specialised cells called xylem and phloem.

Q2) Liverworts thallus belongs to gametophytic generation, and is is haploid in nature.

Q3) Liverworts have unicellular rhizoids they are fund in the ventral side of the gametophyte, they help the plant to attach to the substrate and help in external water retention and conduction.

Q4) Pores are found in the upper side of the thallus, they help in gaseous exchange, the pores leads to an air chamber which contains photosynthetic column of cells and it helps in the gaseous exchange process. Air pores of liverworts remain open all the time.

Q5) The gemmae cup is an asexual reproductive structure, in liverwort the flat body or thallus is a haploid gametophyte which contains gemmae cups on its surface. These are cup like structures containing gemmae.

Q6) Gemmae are haploid in nature. Gemmae are small disc of haploid tissue, they give rise directly to new gametophytes.

Q7) when rain splashes gemmae cups gemmae comes out of the cup and directly gives rise to new plants .

Q8) Archegonia and antheredia are sexual reproductive structures. Antheredia are male plants and archegonia are the female plants.

Q9) Gametes are produced by mitosis.

Q10) After fertilization to form a zygote, the embryos become a sporophyte.

After fertilization zygote divides and grows into a sporophyte, which remains attached to the gametophyte.

11) Sporophyte is diploid in nature. When sperms and eggs join together they produce diploid sporophytes.

Q12) Spore mother cells form spores by meiosis.

Q13) The released spores are haploid in nature. Haploid spore germinate to form haploid thallus that is the gametophyte which can reproduce asexually by gemmae cups.

Q14) A released spore becomes a gametophyte. The haploid spore form a haploid thallus which is called the gametophyte and is haploid in nature.

Q15) Liverworts like most bryophytes are restricted to moist habitats because they require water for reproduction, because in presence of water flagellated sperms swim to reach the egg, these are always small because they are non-vascular plants do not have xylem and phloem for conduction, they depend on the diffusion process which helps in moving in and out of water from the plant body. Diffusion is possible in case of small plants.