Q.57 Match List I with List II
| LIST I (Apomixis Type) | LIST II (Feature) |
|---|---|
| A. Ixeris | I. Precocious desynapsis |
| B. Allium | II. MMC bypasses meiosis |
| C. Taraxacum | III. Asyndetic meiotic prophase |
| D. Antennaria | IV. Premeiotic chromosome doubling |
Choose the correct answer from the options given below:
- A-III, B-IV, C-I, D-II
- A-II, B-I, C-IV, D-III
- A-IV, B-III, C-II, D-I
- A-I, B-II, C-III, D-IV
The correct matching for Q.57 is A-III, B-IV, C-II, D-I.
Detailed Matching Explanation
A. Ixeris → III. Asyndetic meiotic prophase: Ixeris (Asteraceae) shows diplospory where chromosomes fail to synapse properly during meiotic prophase I (asyndesis), producing unreduced gametes.
B. Allium → IV. Premeiotic chromosome doubling: Allium type diplospory involves endomitosis before meiosis—chromosomes double to 4n, then meiosis restores 2n diploid embryo sac.
C. Taraxacum → II. MMC bypasses meiosis: Taraxacum (dandelion) type apospory—meiotic megaspore mother cell (MMC) degenerates; somatic nucellus cells directly form unreduced embryo sac.
D. Antennaria → I. Precocious desynapsis: Antennaria type diplospory features early chromosome desynapsis during prophase I, preventing reduction division.
Incorrect Options Explained
A-III, B-IV, C-I, D-II: Wrong—Taraxacum doesn’t show desynapsis (apospory, not diplospory); Antennaria not MMC bypass.
A-II, B-I, C-IV, D-III: Wrong—Allium not desynapsis; Ixeris not MMC bypass.
A-IV, B-III, C-II, D-I: Wrong—Allium not asyndetic; Taraxacum correct but others mismatched.
A-I, B-II, C-III, D-IV: Wrong—Reversed pairings.Introduction
Match List I with List II Apomixis Type questions test specific meiotic aberrations: Ixeris (asyndetic prophase), Allium (premeiotic doubling), Taraxacum (MMC bypass apospory), Antennaria (precocious desynapsis diplospory). These produce unreduced 2n embryo sacs for clonal seed reproduction.Apomixis Classification
Diplospory (MMC → unreduced ES):
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Allium type: Endomitosis → 4n MMC → meiosis → 2n ES
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Antennaria type: Early desynapsis prophase I
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Ixeris type: Asyndesis (no pairing)
Apospory (somatic → ES):
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Taraxacum type: Nucellus cells → 8-nucleate ES, MMC aborts
Correct Matching Table
Plant Apomixis Type Mechanism A. Ixeris III. Asyndetic No chromosome pairing B. Allium IV. Premeiotic doubling Endomitosis first C. Taraxacum II. MMC bypass Apospory D. Antennaria I. Precocious desynapsis Early prophase failure Exam Memory Aid
“I xeris Asyndetic, Allium Always doubles, Tara(xacum) MMC bypasses, Antenna Desynapsis”. Distinguish diplospory (MMC origin) vs. apospory (somatic origin).
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