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Gymnosperms
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Select one of the following pairs of important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms: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. -
In which one of the following, male and female gametophytes do not have free-living independent existence?Cedrus (deodar) is a gymnosperm.
In gymnosperms the male and female gametophytes do not have an independent free-living existence.
They remain within the sporangia, which are retained on the sporophyte: the male gametophyte is the highly reduced pollen grain, and the female gametophyte develops inside the megasporangium (ovule).
Polytrichum and Funaria are mosses (bryophytes), in which the gametophyte is the dominant, green, free-living plant body.
Pteris is a fern (pteridophyte), in which the gametophyte is a small but independent, free-living, photosynthetic prothallus.
So the male and female gametophytes are not free-living in Cedrus.