Q.77 Post fertilization change in Marchantia involves multiple changes.
Arrange them in the correct sequence.
- Wall of venter divides and gives rise to calyptra.
- Formation of perigynium.
- Cells of capsule wall develop annular thickening.
- Distinct amphithecium is formed.
- Spore mother cells are formed.
Choose the correct answer from the options given below:
(A) A, B, C, D, E
(B) A, B, D, C, E
(C) A, D, B, C, E
(D) A, D, C, B, E
Post-fertilization changes in Marchantia follow a specific sequence starting with venter wall division. Correctly arranging these events is key for exams like CUET PG Botany.
Introduction
Post fertilization changes in Marchantia mark the transition from gametophyte to sporophyte phase in this liverwort. These events—venter wall division to calyptra (A), perigynium formation (B), capsule wall annular thickening (C), distinct amphithecium formation (D), and spore mother cells formation (E)—occur in a precise order after zygote development.
Correct Sequence
The proper order is A → D → C → B → E.
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A first: Immediately post-fertilization, the venter wall divides periclinally to form 2-3 layered calyptra, protecting the young sporophyte.
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D next: Zygote divides into epibasal (forms amphithecium) and hypobasal (forms capsule base) cells; amphithecium differentiates into distinct wall, columella, and sporogenous regions.
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C follows: Amphithecium’s outer cells develop annular thickenings in capsule wall cells for dehiscence during maturity.
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B then: Basal venter cells divide to form perigynium (pseudoperianth), a collar-like sheath outside calyptra, aiding spore dispersal.
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E last: Sporogenous tissue in amphithecium forms diploid spore mother cells, which undergo meiosis to produce spores.
This sequence ensures sporophyte maturation within protective layers.
Option Analysis
| Option | Sequence | Why Incorrect/Correct |
|---|---|---|
| (A) A, B, C, D, E | Venter → Perigynium → Thickening → Amphithecium → SMCs | Wrong: Perigynium (B) forms late; amphithecium (D) precedes capsule features. |
| (B) A, B, D, C, E | Venter → Perigynium → Amphithecium → Thickening → SMCs | Wrong: Perigynium after amphithecium and thickening. |
| (C) A, D, B, C, E | Venter → Amphithecium → Perigynium → Thickening → SMCs | Wrong: Thickening (C) before perigynium (B); actual is C before B. |
| (D) A, D, C, B, E | Venter → Amphithecium → Thickening → Perigynium → SMCs | Correct: Matches embryological development timeline. |
Answer: (D) – Standard in bryophyte texts for Marchantia sporogonium development.
Key Stages Visualized
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Fertilization → Zygote enlarges, venter forms calyptra (A).
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Zygote divides → Distinct amphithecium (D).
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Capsule wall matures with annular thickening (C).
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Perigynium develops as outer sheath (B).
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Spore mother cells differentiate (E), followed by meiosis.
This progression highlights Marchantia’s archegonium-to-sporophyte transformation, vital for spore dispersal.
