Looking for classes? Ksquare Career Institute, Bengaluru →
Select one of the following pairs of important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms:
A
perianth and two integuments
B
embryo development and apical meristem
C
absence of resin duct and leaf venation
D
presence of vessel elements and absence of archegonia
Detailed Solution
Gnetum is the most advanced gymnosperm and shows several resemblances with angiosperms.
Its xylem contains true vessel elements, whereas the xylem of Cycas and Pinus has only tracheids and no vessels.
Archegonia are absent in the female gametophyte of Gnetum, whereas distinct archegonia are present in Cycas and Pinus.
The presence of vessels and the absence of archegonia are both characteristic features of angiosperms.
Gnetum also has broad leaves with reticulate venation like dicots, but the other pairs given do not correctly combine two such distinguishing features.
So the pair of features is the presence of vessel elements and the absence of archegonia.
Its xylem contains true vessel elements, whereas the xylem of Cycas and Pinus has only tracheids and no vessels.
Archegonia are absent in the female gametophyte of Gnetum, whereas distinct archegonia are present in Cycas and Pinus.
The presence of vessels and the absence of archegonia are both characteristic features of angiosperms.
Gnetum also has broad leaves with reticulate venation like dicots, but the other pairs given do not correctly combine two such distinguishing features.
So the pair of features is the presence of vessel elements and the absence of archegonia.