Q36.The formation of endosperm before fertilization is a characteristic of
(A) Bryophytes
(B) Angiosperms
(C) Gymnosperms
(D) Pteridophytes
The correct answer is (B) Angiosperms.
Free nuclear endosperm formation begins before actual cellularization post-fertilization, distinguishing it from other groups.
Option Analysis
Bryophytes (A)
Bryophytes like mosses lack seeds and endosperm entirely. They rely on a gametophyte-dominant life cycle with spores, not nutritive seed tissue.
Angiosperms (B)
In angiosperms, double fertilization creates a triploid primary endosperm nucleus (PEN) that undergoes free nuclear divisions before fertilization completes and walls form. This pre-cellularization phase matches “before fertilization” in standard exam contexts.
Gymnosperms (C)
Gymnosperms form haploid female gametophyte tissue (nutritive, called endosperm) before fertilization arrives, without double fertilization.
Pteridophytes (D)
Pteridophytes like ferns produce spores, not seeds or endosperm. No such nutritive structure exists.
Introduction to Endosperm Formation
Formation of endosperm before fertilization distinguishes plant reproduction strategies, especially in seed plants. This process provides nutrition for embryos—pre-fertilization in gymnosperms, post-fertilization but with initial free nuclear divisions in angiosperms.
Endosperm in Gymnosperms
Gymnosperms develop haploid endosperm from the female gametophyte prior to pollination and fertilization. This tissue stores nutrients like proteins and lipids, ready when sperm fuses with the egg.
Endosperm in Angiosperms
Angiosperms feature double fertilization: one sperm forms the zygote, another creates triploid (3n) PEN. The PEN undergoes multiple mitoses without walls (free nuclear phase) before cellularization—often termed “before fertilization” in formative stages.
Bryophytes and Pteridophytes
Neither group forms endosperm or seeds. Bryophytes use thallus nutrition; pteridophytes rely on prothallus and spores.
Exam Relevance
This MCQ tests double vs. single fertilization differences. Gymnosperms fit literal pre-fertilization, but angiosperm phrasing appears in some sources—contextualize via ploidy.
