Monosporic Development — Embryo Sac From ONE Functional Megaspore
✅ Asked in NEET 2019Which one of the following statements regarding post-fertilisation development in flowering plants is incorrect? (NEET 2019)
Which one of the following statements regarding post-fertilisation development in flowering plants is incorrect? (NEET 2019)
Functional megaspore in an angiosperm develops into an (NEET 2017)
Answer & NCERT explanation
Correct answer: A — Ovules develop into embryo sac.
Ovules are structures that contain the female gametophyte (embryo sac) before fertilization. Post-fertilization, ovules develop into seeds, not embryo sac. The embryo sac is already present before fertilization. Other options are correct: ovary becomes fruit, zygote becomes embryo, and central cell develops into endosperm after triple fusion.
Read more NCERT concept on the PYQ
Female gametophyte: In a majority of flowering plants, one of the megaspores is functional while the other three degenerate. Only the functional megaspore develops into the female gametophyte (embryo sac). This method of embryo sac formation from a single megaspore is termed monosporic development. What will be the ploidy of the cells of the nucellus, MMC, the functional megaspore and female gametophyte?
In the MAJORITY of flowering plants, ONLY ONE of the four megaspores is FUNCTIONAL while the OTHER THREE DEGENERATE. The single functional megaspore develops into the female gametophyte (embryo sac). This pattern — embryo sac formation from a SINGLE megaspore — is called MONOSPORIC DEVELOPMENT (Polygonum type). After fertilisation, the structural mapping is: OVULE → SEED (not embryo sac; the embryo sac already exists before fertilisation, IN the ovule). OVARY → FRUIT. ZYGOTE → EMBRYO. CENTRAL CELL (after triple fusion) → ENDOSPERM. Functional megaspore itself develops into the EMBRYO SAC, NOT into the embryo. Don't confuse 'functional megaspore → embryo sac' with 'zygote → embryo'.
NEET 2019 trap: 'Ovules develop into embryo sac' was the INCORRECT statement. Post-fertilisation, OVULES → SEEDS. The embryo sac already exists inside the ovule BEFORE fertilisation (it forms from the functional megaspore). NEET 2017: functional megaspore → EMBRYO SAC (not embryo, not endosperm, not ovule). Memorise the post-fertilisation transformations: ovule → seed, ovary → fruit, zygote → embryo, central cell → endosperm, integuments → seed coat, micropyle → micropyle (persists as a pore).
Post-fertilisation, ovules develop into the embryo sac and the functional megaspore develops into the embryo.
Ovules → SEEDS (post-fertilisation). Embryo sac forms BEFORE fertilisation from the functional megaspore. Functional megaspore → EMBRYO SAC (not embryo).
Ovule → SEED. Ovary → FRUIT. Zygote → EMBRYO. Central cell → ENDOSPERM. Functional megaspore → EMBRYO SAC (NOT embryo).
- Monosporic development = embryo sac forms from a SINGLE functional megaspore (3 others degenerate).
- Post-fertilisation: Ovule → SEED (NOT embryo sac); Ovary → FRUIT; Zygote → EMBRYO; Central cell → ENDOSPERM.
- Functional megaspore → EMBRYO SAC (NEET 2017 direct answer).
- Polygonum-type embryo sac (monosporic, 8-nucleate, 7-celled) is the majority pattern in flowering plants.
What is Monosporic Development?
What did NEET 2019 ask on Monosporic Development?
What is the most common NEET trap on Monosporic Development?
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