Explain briefly the following terms with suitable examples:-
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
Ncert solutions for Class 11th Biology Chapter 3 Exercise 8
Answers
2 IT IS THE MALE PART PRESENT IN ONE PHYLUM OF PLATAE KINGDOM
3 IT IS THE FEMALE PART
4 DIPLONTIC STAGE IS THE STAGE WHERE AN ORGANISMS HAS DOBLE THE AMOUNT OF GENETIC INFORMATOIN
5 IT IS THE SPOROPHYTIC STATE OF AN ORGANISM{NOT CONFIDENT}
6 IT IS DEFINE AS THE ORGANISM HAVING SAME TYPE OF MALE AND FEMALE GAMETE
Answer:
i) Protonema is the haploid stage in the bryophyte lifecycle where thread-like chain of cells are formed Ex: In mosses protonema develops directly from a spore.
ii) Antheridium – The male sex organ, producing male gametes in bryophyte and pteridophytes is called antheridium. Ex: many fungi and algae have antheridia during their reproductive phases.
iii) Archegonium is a female reproductive organ of bryophytes which is flask-shaped and produces a single egg. Observed in pteridiophytes, gymnosperms, bryophytes, they are jacketed and multicellular, possessing a neck and a swollen venter.
iv) Diplontic – Life cycle in which dominant free living phase is diploid, generating haploid gametes. Ex: Sargassum
v) A leaf which bears sporangia is called as sporophyll, which may be microsporophyll or megasporophyll. These structures combine to form strobini(cones) Ex: Pinus
vi) Isogamy – Sexual reproduction that takes place through fusion of two gametes which can be flagellated and similar in size or non-flagellated (non-motile) but similar in size. Such reproduction is called isogamy. Ex: Ectocarpus