The chief water conducting elements of xylem in gymnosperms are
vessels
fibres
tansfusion tissue
tansfusion tissue
D.
tansfusion tissue
The tracheids are elongated, angular dead cells with hard lignified wide lumen and narrow end walls. The walls of tracheids posses different types of thickenings and the unthickened areas of its wall allow the rapid movement of water from one tracheid to another. Tracheids are the characteristic cells types of xylem tissue in gymnosperms and pteridophytes, where they are chief elements of water conduction.
Gymnosperms are also called soft wood spermatophytes because they lack
cambium
phloem fibres
thick-walled tracheids
thick-walled tracheids
Read the following five statements and answer as asked to them
I. In Equisetum the female gametophyte is retained on the parent sporophyte.
II. In Ginkgo male gametophyte is not independent.
III. The sporophyte in Riccia is more developed than that in Polytrichum.
IV. Sexual reproduction in Volvox is isogamous.
V. The spores of the above statements are correct?
Two
Three
Four
Four
Read the following five statements (I to V) and select the option with all correct statements.
I Mosses and lichens are the first organisms to colonise a bare rock.
II .Selaginella is a homosporous pteridophyte.
III. Coralloid roots in Cycas have VAM.
IV. Main plant body in bryophytes is gametophytic, whereas in pteridophytes it is sporophytic.
V. In gymnosperms, male and female gametophytes are present within sporangia located on sporophyte.
I, III and IV
II, III and IV
I, IV and V
I, IV and V
The unequivocal proof of DNA as the genetic material came from the studies on a
I) The sporophyte in liverworts is more elaborate than that in mosses
II) Salvinia is heterosporous
III) The life -cycle in all seed - bearing plants is diplontic
IV) In pinus male and female cones are borne on different trees
Statements (I) and (III)
Statement (I) and (IV)
Statements (II) and (III)
Statements (II) and (III)
Selaginella and Salvinia are considered to represent a significant step towards evolution of seed habit because
female gametophyte is free and gets dispersed like seeds
female gametophyte lacks archegonia
megaspores possess endosperm and embryo surrounded by a seed coat
megaspores possess endosperm and embryo surrounded by a seed coat
Male and female gametophytes are independent and free - living in
mustard
castor
Pinus
Pinus
