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Top-shaped multiciliate male gametes, and the mature seed which bears only one embryo with two cotyledons, are characteristic features of -
A
Gamopetalous angiosperms
B
Conifers
C
Polypetalous angiosperms
D
Cycads
Detailed Solution
In most seed plants the male gametes are non-motile and are carried to the egg by the pollen tube.
Cycads (for example Cycas) are exceptional: their male gametes are very large, top-shaped and bear a spiral band of numerous cilia (multiciliate), so they are motile.
Although the ovule may contain more than one archegonium, the mature seed of Cycas usually bears only one embryo, with two cotyledons.
Conifers (such as Pinus) have non-motile male gametes and their embryos usually have several cotyledons.
Angiosperms have non-motile male gametes.
So these are the characteristic features of cycads.
Cycads (for example Cycas) are exceptional: their male gametes are very large, top-shaped and bear a spiral band of numerous cilia (multiciliate), so they are motile.
Although the ovule may contain more than one archegonium, the mature seed of Cycas usually bears only one embryo, with two cotyledons.
Conifers (such as Pinus) have non-motile male gametes and their embryos usually have several cotyledons.
Angiosperms have non-motile male gametes.
So these are the characteristic features of cycads.