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How does fertilisation occur in gymnosperms?
Fertilisation is of siphonogamous type, i.e.. the male gametes are carried to the archegonia through pollen tube in gymnosperms. In Cycas only, pollen tube functions as haustorium and fertilisation occurs by zoodiogamy.
Fertilisation is of siphonogamous type, i.e.. the male
See lessgametes are carried to the archegonia through pollen
tube in gymnosperms. In Cycas only, pollen tube
functions as haustorium and fertilisation occurs by
zoodiogamy.
Which is the most highly evolved gymnosperm? What are its features?
The most highly evolved gymnosperm is Gnetum. It belongs to Gnetopsida. The Gnetum looks like an angiosperm tree with reticulate venation in leaves and branching pattern, vessels in xylem and presence of archegonia in female gametophyte.
The most highly evolved gymnosperm is Gnetum. It
See lessbelongs to Gnetopsida. The Gnetum looks like an
angiosperm tree with reticulate venation in leaves and
branching pattern, vessels in xylem and presence of
archegonia in female gametophyte.
What is the economic importance of gymnosperms?
Economic importance of gymnosperms are (i) Resins obtained from conifers have commercial importance. (ii) The seeds of Pinus are edible. (iii) Many gymnosperms yield medicinal compounds. (iv) Some gymnosperms are ornamental plants.
Economic importance of gymnosperms are
See less(i) Resins obtained from conifers have commercial
importance.
(ii) The seeds of Pinus are edible.
(iii) Many gymnosperms yield medicinal compounds.
(iv) Some gymnosperms are ornamental plants.
How does pollination occur in gymnosperms and how the pollen grains approach ovules?
Pollination (by wind) in gymnosperms is direct, as stigma is absent. The pollen grains reach the micropylar ends of ovules directly.
Pollination (by wind) in gymnosperms is direct, as stigma
See lessis absent. The pollen grains reach the micropylar ends of
ovules directly.
Why seeds remain exposed in gymnosperms?
Seeds in gymnosperms remain exposed over the surface of the megasporophylls. This is because megasporophylls are not folded to form pistils like in angiosperms.
Seeds in gymnosperms remain exposed over the surface
See lessof the megasporophylls. This is because megasporophylls
are not folded to form pistils like in angiosperms.
Why Cycas is called a living fossil?
Cycas is a living representative of once a large group of gymnosperms which has became largely extinct.
Cycas is a living representative of once a large group of
See lessgymnosperms which has became largely extinct.
Why the name given double fertilisation to fertilisation in angiosperms?
The occurrence of two types of fertilisation in the same embryo sac is called double fertilisation that occurs in angiosperms.
The occurrence of two types of fertilisation in the same
See lessembryo sac is called double fertilisation that occurs in
angiosperms.
Most algal genera show haplontic life cycle. Name an alga which is
Haplodiplontic Ulva, Dictyota. Diplontic Fucus, Cladophora, Glomerata.
Haplodiplontic Ulva, Dictyota.
See lessDiplontic Fucus, Cladophora, Glomerata.
When does meiosis occur in a diplontic life cycle?
Meiosis occurs during spore formation in a diplontic life cycle.
Meiosis occurs during spore formation in a diplontic life
See lesscycle.
Explain alternation of generations in plants?
Alternation of generations is regular switch over from gamete bearing haploid gametophyte to haploid spore producing diploid sporophyte.
Alternation of generations is regular switch over from
See lessgamete bearing haploid gametophyte to haploid spore
producing diploid sporophyte.