19. Match the two columns following asexual reproduction of plants and apomixes:
    
    (1) A – (i); B – (ii); C – (iii); D – (iv)
    (2) A – (ii); B – (iii); C – (iv); D – (i)
    (3) A – (ii); B – (i); C – (iii); D – (iv)
    (4) A – (ii); B – (i); C – (iv); D – (iii)

he match between asexual reproduction in plants and apomixis in the columns is:

(2) A – (ii); B – (iii); C – (iv); D – (i)

Explanation (general types of apomixis):

• A corresponds to diplospory (ii), where the embryo sac arises from an unreduced megaspore mother cell.

• B corresponds to apospory (iii), where the embryo sac arises from somatic cells of the ovule, bypassing meiosis.

• C corresponds to adventive embryony (iv), where embryos develop directly from somatic ovular cells like nucellus or integuments.

• D corresponds to normal sexual reproduction (i), involving meiosis and fertilization.

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Introduction

Apomixis is an asexual mode of reproduction in plants where seeds form without fertilization, producing clonal offspring identical to the parent. Different types of apomixis vary based on the origin of the embryo sac or embryo, including diplospory, apospory, and adventive embryony. These mechanisms offer important insights for plant breeding and propagation.

Types of Apomixis and Their Characteristics

• Diplospory (A – ii):
  The embryo sac develops from an unreduced megaspore mother cell (megaspore mother cell bypasses meiosis) forming the female gametophyte directly.

• Apospory (B – iii):
  The embryo sac originates from somatic nucellar or integument cells rather than from meiosis products, bypassing the normal gametogenesis pathway.

• Adventive Embryony (C – iv):
  Embryos form directly from diploid somatic cells of the ovule, resulting in clonal embryos without embryo sac formation.

• Normal Sexual Reproduction (D – i):
  Involves meiosis producing haploid spores and fertilization leading to genetic recombination and variability.

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Summary Table: Association Between Apomixis Types and Developmental Origins

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Conclusion

The correct matching aligns diplospory with A, apospory with B, adventive embryony with C, and normal sexual reproduction with D, corresponding to option (2). Apomixis represents fascinating reproductive diversity with major implications in agriculture.