Explainbriefly the following terms with suitable examples:-
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
Explainbriefly the following terms with suitable examples:-
(i) protonema
(ii) antheridium
(iii) archegonium
(iv) diplontic
(v) sporophyll
(vi) isogamy
(i) Protonema –It is the first stage in the life cycle of a moss, developingdirectly from the spore. It consists of creeping, green, branched,and often filamentous structures.
(ii) Antheridium– It is the male sex organpresent in bryophytes and pteridophytes and is surrounded by a jacketof sterile cells. It encloses the sperm mother cells, which give riseto the male gametes.
(iii) Archegonium– It is the female sex organpresent in bryophytes, pteridophytes, and gymnosperms. In bryophytesand pteridophytes, it generally has a swollen venter and a tubularneck, and contains the female gamete called the egg.
(iv) Diplontic– It is the term used for thelife cycles of seed-bearing plants (gymnosperms and angiosperms). Inthese plants, the diploid sporophyte is dominant, photosynthetic, andindependent. The gametophyte is represented by a single-celled (or afew-celled) structure.
(v) Sporophyll– In pteridophytes, thesporophytic plant body bears sporangia. These sporangia are subtendedby leaf-like appendages known as sporophylls. In gymnosperms,microsporophylls and megasporophylls are found. These bearmicrospores and megaspores respectively.
(vi) Isogamy –It is a type of sexual reproduction involving the fusion ofmorphologically-similar gametes. This means that the gametes are ofthe same size, but perform different functions. This type ofreproduction is commonly observed in Spirogyra.
(i) Protonema –It is the first stage in the life cycle of a moss, developingdirectly from the spore. It consists of creeping, green, branched,and often filamentous structures.
(ii) Antheridium– It is the male sex organpresent in bryophytes and pteridophytes and is surrounded by a jacketof sterile cells. It encloses the sperm mother cells, which give riseto the male gametes.
(iii) Archegonium– It is the female sex organpresent in bryophytes, pteridophytes, and gymnosperms. In bryophytesand pteridophytes, it generally has a swollen venter and a tubularneck, and contains the female gamete called the egg.
(iv) Diplontic– It is the term used for thelife cycles of seed-bearing plants (gymnosperms and angiosperms). Inthese plants, the diploid sporophyte is dominant, photosynthetic, andindependent. The gametophyte is represented by a single-celled (or afew-celled) structure.
(v) Sporophyll– In pteridophytes, thesporophytic plant body bears sporangia. These sporangia are subtendedby leaf-like appendages known as sporophylls. In gymnosperms,microsporophylls and megasporophylls are found. These bearmicrospores and megaspores respectively.
(vi) Isogamy –It is a type of sexual reproduction involving the fusion ofmorphologically-similar gametes. This means that the gametes are ofthe same size, but perform different functions. This type ofreproduction is commonly observed in Spirogyra.
