The trap: NEET frequently tests whether you can distinguish parts of a flower that look similar in name but differ in function — particularly confusing microsporogenesis (pollen formation) with megasporogenesis (embryo sac formation), and mixing up the products of each process.
A typical flower has four whorls: calyx (sepals), corolla (petals), androecium (stamens), and gynoecium (carpels). The androecium is the male reproductive unit; each stamen consists of a filament and an anther. The gynoecium is the female unit; each carpel has a stigma, style, and ovary (NCERT Class 11 Biology Chapter 5, pages 63–65).
Microsporogenesis: Inside the anther's microsporangia, microspore mother cells (2n) undergo meiosis to produce tetrads of microspores (n). Each microspore develops into a pollen grain — a 2-celled (generative + vegetative) or 3-celled structure at shedding.
Megasporogenesis: Inside the ovule's nucellus, a megaspore mother cell (2n) undergoes meiosis to form four megaspores. Typically only one (chalazal) is functional — the other three degenerate. The functional megaspore undergoes three mitotic divisions to produce a 7-celled, 8-nucleate embryo sac (Polygonum type): 3 antipodals, 2 synergids, 1 egg cell, and a central cell with 2 polar nuclei.
Watch-out for NEET: The number of pollen grains from one microspore mother cell is 4 (meiosis produces 4 functional microspores). From one megaspore mother cell, only 1 functional megaspore survives. Questions often swap these numbers or ask about the ploidy at each stage.
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
How many pollen grains are formed from one microspore mother cell?
Answer: D. One microspore mother cell (2n) undergoes meiosis to produce a tetrad of 4 microspores, each developing into a pollen grain (NCERT Class 12 Biology Chapter 1, page 6).
Why A is wrong: A — This confuses microsporogenesis with megasporogenesis, where only 1 functional megaspore survives per mother cell.
Why B is wrong: B — There is no stage in microsporogenesis that yields only 2 functional products from one mother cell.
Why C is wrong: C — 8 is the number of nuclei in a mature embryo sac (from mitotic divisions of the megaspore), not the product of meiosis in a microspore mother cell.
In a plant with 2n = 24, consider four cells: a microspore mother cell, a microspore, a generative cell (inside a mature pollen grain), and a nucellus cell of the ovule. What is the chromosome number of each, in that order?
Answer: A. The microspore mother cell (pollen mother cell) is a sporophytic cell, so it is diploid: 2n = 24. It undergoes meiosis (microsporogenesis) to form a tetrad of microspores, so each microspore is haploid: n = 12 (NCERT Class 12 Biology, Chapter 1, page 6). The generative cell arises from mitotic division of the microspore's nucleus inside the pollen grain; mitosis does not change chromosome number, so the generative cell stays haploid: n = 12 (page 7). The nucellus is the mass of cells enclosed within the integuments of the ovule — ordinary sporophytic tissue that has not undergone meiosis, so it remains diploid: 2n = 24 (page 9). The sequence is therefore 24, 12, 12, 24.
Why B is wrong: B starts the microspore mother cell at n = 12, treating it as already haploid — but the mother cell is sporophytic tissue that has not yet undergone meiosis, so it is 2n = 24, not n = 12; it also ends with the nucellus at 24, which happens to be right, but the first two values are swapped.
Why C is wrong: C keeps the generative cell at 2n = 24 and the nucellus at n = 12 — the reverse of the truth: the generative cell is haploid (it comes from meiosis followed by mitosis, which does not restore ploidy), while the nucellus is diploid sporophytic tissue that never underwent meiosis.
Why D is wrong: D alternates 24/12/24/12, wrongly making the generative cell diploid (2n = 24) as if mitosis after meiosis restored the chromosome number, and wrongly making the nucellus haploid (n = 12) as if it were gametophytic tissue.
A mature embryo sac of the Polygonum type is:
Answer: B. The mature embryo sac has 7 cells (3 antipodals + 2 synergids + 1 egg + 1 central cell) and 8 nuclei (the central cell contains 2 polar nuclei) — NCERT Class 12 Biology Chapter 1, page 11.
Why A is wrong: A — Reverses the relationship: the sac has 7 cells (not 8) because two polar nuclei share one central cell.
Why C is wrong: C — This implies each cell has one nucleus and there are 8 cells, ignoring the binucleate central cell.
Why D is wrong: D — This drops one nucleus; the central cell has 2 polar nuclei making the total 8, not 7.
Which cells in the embryo sac have the filiform apparatus?
Answer: B. The filiform apparatus is a finger-like projection at the micropylar end of each synergid that guides the pollen tube into the embryo sac (NCERT Class 12 Biology Chapter 1, page 11).
Why A is wrong: A — Antipodal cells are at the chalazal end and lack filiform apparatus; they are involved in nutrition.
Why C is wrong: C — The egg cell is between the two synergids but does not bear the filiform apparatus.
Why D is wrong: D — The central cell contains polar nuclei and participates in triple fusion; it has no filiform apparatus.
A pollen grain at the time of shedding from the anther is typically:
Answer: C. Most angiosperm pollen grains are shed at the 2-celled stage (vegetative cell + generative cell). In some species (e.g., grasses), the generative cell divides before shedding giving a 3-celled grain, but the typical/default is 2-celled (NCERT Class 12 Biology Chapter 1, page 7).
Why A is wrong: A — A 1-celled stage represents the microspore before mitosis; by shedding, at least one mitotic division has occurred.
Why B is wrong: B — While some species shed 3-celled pollen, the question asks for the typical condition; 2-celled is the standard NCERT answer.
Why D is wrong: D — A 4-celled structure describes the tetrad of microspores, not the internal cellular organization of a single pollen grain.
During microsporogenesis, the process that converts a microspore mother cell into a tetrad of microspores is:
Answer: D. Microsporogenesis involves meiosis of the diploid microspore mother cell to yield four haploid microspores (NCERT Class 12 Biology Chapter 1, page 6).
Why A is wrong: A — Mitosis would produce diploid copies; it does not reduce chromosome number. Mitosis occurs AFTER microspore formation (to form the 2-celled pollen grain).
Why B is wrong: B — Endomitosis is chromosome duplication without cell division (polyploidy); it is unrelated to spore formation.
Why C is wrong: C — Amitosis is direct division without spindle formation, seen in some protists; it does not occur in standard sporogenesis.
How many meiotic divisions are required to produce 200 pollen grains?
Answer: C. Each meiotic division of one microspore mother cell produces 4 microspores (→ 4 pollen grains). Therefore, 200 pollen grains require 200 ÷ 4 = 50 meiotic divisions.
Why A is wrong: A — This assumes one meiosis yields one pollen grain, confusing microsporogenesis (4 per division) with megasporogenesis (1 functional product).
Why B is wrong: B — This uses a factor of 2 (as in mitosis), not the correct factor of 4 from meiosis.
Why D is wrong: D — This multiplies instead of dividing, producing an impossibly large number.
In the Polygonum-type embryo sac, the egg apparatus consists of:
Answer: A. The egg apparatus is the group of three cells at the micropylar end: one egg cell flanked by two synergids. Antipodal cells are at the chalazal end and are not part of the egg apparatus (NCERT Class 12 Biology Chapter 1, page 11).
Why B is wrong: B — Antipodal cells are at the opposite (chalazal) end and do not form part of the egg apparatus (trap: similar-term confusion between micropylar and chalazal cell groups).
Why C is wrong: C — There is only 1 egg cell per embryo sac; stating 2 egg cells contradicts the Polygonum-type organization.
Why D is wrong: D — Mixing cells from both ends of the embryo sac; the egg apparatus is exclusively micropylar (egg + 2 synergids).
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Given
A flowering plant has 25 megaspore mother cells in its ovules.
Required
How many functional embryo sacs will form, assuming standard Polygonum-type development?
Concept
In monosporic (Polygonum-type) development, each megaspore mother cell undergoes meiosis to produce 4 megaspores, but only 1 (chalazal) is functional. Each functional megaspore develops into one embryo sac.
Formula
Functional embryo sacs = Number of megaspore mother cells × 1
(Since 3 out of 4 megaspores degenerate per mother cell.)
Substitution
Functional embryo sacs = 25 × 1 = 25
Calculation
25 megaspore mother cells → 25 functional megaspores → 25 embryo sacs.
Note: The integer "25" is a counting number (exact); it does not limit significant figures.
Final answer
25 embryo sacs (and 75 degenerated polar megaspores total).
Common trap
Confusing this with microsporogenesis output: if the question had asked about microspore mother cells, the answer would be 25 × 4 = 100 pollen grains. The asymmetry (4 functional in male, 1 functional in female) is the high-frequency NEET trap here.
Similar NEET-style question
If 10 microspore mother cells and 10 megaspore mother cells undergo sporogenesis, how many total functional pollen grains and embryo sacs are produced? (Answer: 40 pollen grains + 10 embryo sacs = 50 functional products.)
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Microsporogenesis: pollen mother cell → meiosis → 4 microspores → pollen grain. Megasporogenesis: megaspore mother cell → meiosis → 4 megaspores → 1 functional → embryo sac (8-nucleate, 7-celled — Polygonum type).
-- NCERT Class 12 Biology, Ch. 1, p. 6More in Reproduction: 10 exam traps and mistakes · 1 question pattern from its other lessons.
6 questions from NEET 2020, 2021, 2025, 2026. Answers verified against NTA official keys.
How many theca are present in each lobe of a typical bilobed angiosperm anther ?
Match List-I with List-II. Choose the correct answer from the options given below. (a) (b) (c) (d)
Page numbers are the ones printed in the current NCERT textbook (2023 rationalised edition), unless marked pre-2023. The books are free at ncert.nic.in.
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