#double fertilization

BOTANY

During double fertilization, the sperm that fuses with the polar nuclei results in the formation of which structure?

The fusion of one sperm with the two polar nuclei forms the triploid endosperm, which provides nutrition to the embryo. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Morphology and Anatomy of Flowering Plants, Topic: Plant structure and tissue systems.

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plant Development - 1

Double fertilization involves:

Double fertilization defines unique sexual reproduction in flowering plants offering evolutionary advantage. Upon pollen tube entry through synergid filiform apparatus, it ruptures releasing two sperm cells into embryo sac. One sperm cell fuses with haploid egg nucleus forming diploid zygote that develops via embryogenesis stages into embryo. Second sperm fuses with homodiploid central cell containing two polar nuclei producing triploid primary endosperm nucleus that proliferates as nutritive endosperm tissue. Synergid degenerates facilitating release and antipodals eventually senesce. Dual fu

Ref: Weterings & Russell, Trends Plant Sci 2004; Berger: double fertilization involves one sperm-egg, one sperm-central cell fusion.

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Plant Classification

Double fertilization in gnetophytes produces

Fertilization behavior in Gnetales demonstrates parallel to angiosperms: two non-flagellated sperm nuclei delivered via pollen tube, one syngamy with egg forming diploid zygote future embryo, second fuses typically with ventral canal nucleus creating additional diploid nucleus which aborts undergoing degeneration without forming persistent triploid nutritive tissue unlike angiosperms where triploid endosperm proliferates. Initial products therefore two diploid nuclei from double fertilization, contrasting triploid product in flowering plants. This homoplasious double fertilization illustrates

Ref: Campbell Biology, 12th ed., Chapter 30: Double fertilization Gnetophyte diploid products aborting endosperm

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Plant Classification

The nutritive tissue formed as a result of double fertilization in angiosperms is

Following pollen tube discharge into synergid, central cell with two polar nuclei fused with second sperm nucleus undergoes triple fusion, establishing triploid primary endosperm nucleus with two maternal to one paternal genome ratio enabling genomic imprinting crucial for seed development regulating nutrient allocation. Subsequent free-nuclear divisions produce cellular endosperm packed with starch, storage proteins lipids consumed by embryo during maturation in exalbuminous seeds or retained in albuminous seeds like cereals. Diploid endosperm occurs only in basal Nymphaeales and Austrobailey

Ref: Campbell Biology, 12th ed., Chapter 38: Endosperm triploid development after double fertilization

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Sexual Reproduction in flowering Plants

While double fertilization is a later topic, the structure 'Central Cell' is prepared for it. Before fertilization, the

In the mature embryo sac prior to fertilization, the central cell contains two polar nuclei. While they may fuse just before fertilization to form a secondary nucleus (2n), the typical description of the mature sac characterizes the cell as having two polar nuclei (n+n).

Ref: Central part of the embryo sac showing two distinct polar nuclei.

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