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The important features distinguishing Gnetum from Cycas and Pinus and showing affinities with angiosperms are presence of vessel elements and absence of archegonia.

1. The male gametes of bryophytes are biflagellate and those of pteridophytes are multiflagellate, except Selaginella having biflagellate gametes. The male gametes of gymnosperms are non-motile except those of Cycas having multiciliate gametes.
2. In gymnosperms, the pollen chamber represents a cavity in the ovule in which pollen grains are stored after pollination within the pollen chamber, the generative cell nucleus divides to form two genetic nuclei and the tube cells elongates results in the formation of pollen tube, the pollen tube penetrates the female gametophyte and the sperm nuclei and then it pass through the tube. So, one of the sperm nuclei get fused with the egg results in the formation of zygote (diploid).
3. Conifers (Gymnosperms) differ from grasses (angiosperms) because in gymnosperms the female gametophyte is actually endosperm which is made before fertilisation. While in grasses endosperm is a tissue formed by the fertilisation of second male gamete to polar nuclei. Moreover in gymnosperms the endosperm is a haploid tissue while in angiosperms it is triploid.
4. Peritrichous flagellation : Flagella all around, e.g. Escherichia coli. Living fossil : Organisms which have undergone very little change since they first evolved, e.g. Ginkgo.

Correct answer: Conifers (Gymnosperms) differ from grasses (angiosperms) because in gymnosperms the female gametophyte is actually endosperm which is made before fertilisation. While in grasses endosperm is a tissue formed by the fertilisation of second male gamete to polar nuclei. Moreover in gymnosperms the endosperm is a haploid tissue while in angiosperms it is triploid.

Solution

The correct choice is the one contrasting gymnosperms and angiosperms by endosperm formation. In gymnosperms, the female gametophyte serves as the nutritive tissue and is haploid, while in angiosperms endosperm forms after double fertilization and is typically triploid.

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